NFPA 13 2022 vs 2025 Edition

• Testing showed EC uprights with K-11.2 and K-14.0 could work in OH1 and OH2 above 30 ft.
• That performance was not demonstrated for pendent versions with K ≤ 22.4.
• This ties into the broader height limits for nonstorage occupancies in 19.2.3.2.5.

11.2.3 Sprinkler Spacing (Extended Coverage Upright and Pendent Spray Sprinklers).

• 11.2.3.4.3 (New in 2025): “Where sprinklers are installed in every channel formed by solid obstructed construction with the deflectors above the bottom of the structural members, the structural members shall be considered baffles in accordance with 11.2.3.4.2.”

11.2.4 Deflector position (Extended Coverage Upright and Pendent Spray Sprinklers).

• 11.2.4.2 Deflector Orientation
  • 11.2.4.2.1:
    • 2022: “Roofs and ceilings having a pitch not exceeding 2 in 12 (16.7 percent) are considered horizontal in the application of 11.2.4.2, and sprinklers shall be permitted to be installed with deflectors horizontal.”
    • 2025: “Roofs and ceilings having a pitch not exceeding 2 in 12 (16.7 percent) are considered horizontal in the application of 11.2.4.2, and sprinklers installed under horizontal ceilings shall be permitted to be installed with deflectors parallel to the floor.”

11.2.5 Obstructions to Sprinkler Discharge (Extended Coverage Upright and Pendent Spray Sprinklers).

11.2.5.3 Obstructions that prevent discharge from reaching hazard (2022 origin 11.2.5.3.1–3.5)

• 2022:
  • 11.2.5.3.1 – Defined when horizontal plane obstructions > 18 in below deflector must be treated.
  • 11.2.5.3.2 – Required sprinklers under fixed obstructions > 4 ft wide.
  • 11.2.5.3.3 – Exempted non-fixed items (e.g., conference tables).
  • 11.2.5.3.4 – Required intermediate-level/rack-type (or shielded) sprinklers under open gratings, to prevent cold solder from overhead sprinklers.
  • 11.2.5.3.5 – Same intermediate-level/rack or shielding requirement for sprinklers under round ducts.
• 2025:
  • “Continuous or noncontinuous obstructions that interrupt the water discharge in a horizontal plane more than 18 in. (450 mm) below the sprinkler deflector in a manner to limit the distribution from reaching the protected hazard shall comply with 9.5.3.3. (See A.‍9.5.5.3.1.)”
  • So, all detailed requirements for fixed obstructions > 4 ft, treatment of conference tables, open grating, round ducts, etc., are now centralized in Chapter 9 instead of being repeated in Section 11.

11.3 Extended Coverage Sidewall Spray Sprinklers. (See 10.2.9.2.)

Added a commentary to the enhanced content “Unless the rationale for the extended coverage sprinkler requirements differs from those for standard sidewall sprinklers, commentary regarding related items in Section 10.3 is not repeated in Section 11.3.”

11.3.2 Where extended-coverage sidewall sprinklers can be used

2022: Extended coverage sidewall spray sprinklers could only be installed in:

• Light hazard occupancies with smooth, horizontal or sloped flat ceilings.
• Ordinary hazard occupancies with smooth, flat ceilings, where specifically listed.
• Unobstructed construction with smooth, flat ceilings, slope ≤ 1 in 6.
• Unobstructed or noncombustible obstructed construction, where specifically listed.
• Within trusses/bar joists with web members ≤ 1 in, or trusses spaced > 7½ ft OC, with ceiling slope ≤ 1 in 6.
• On sloped ceilings > 2 in 12 where installed per 11.3.6.2.2.
• In each bay of obstructed construction with solid structural members extending below the deflector.
• To protect areas below a single overhead door.

2025: The above eight permitted uses are retained, plus two new permitted applications:

• For the protection of exterior projections and similar structures.
• Under cars in car stackers and car lift systems, with sprinklers placed under each level of cars (with additional explanatory commentary in A.10.3.2(9)).

11.3.6.3 Obstructions that prevent discharge from reaching the hazard

• 2022:
  • 11.3.6.3.1: Continuous or noncontinuous obstructions that interrupt the discharge in a horizontal plane more than 18 in (450 mm) below the deflector, and that limit distribution reaching the hazard, must comply with this section.
  • 11.3.6.3.2: Sprinklers must be installed under fixed obstructions over 4 ft (1.2 m) wide.
  • 11.3.6.3.3: Sprinklers are not required under obstructions that are not fixed in place, such as conference tables.
• 2025: The detailed sidewall-specific text is deleted and replaced with a pointer to the general rules:
  • “Continuous or noncontinuous obstructions that interrupt the water discharge in a horizontal plane more than 18 in. (450 mm) below the sprinkler deflector in a manner to limit the distribution from reaching the protected hazard shall comply with 9.5.5.3.”
  • All the detailed “fixed > 4 ft wide → sprinkler required underneath; movable tables → sprinkler not required” logic now lives in §9.5.5.3 for all sprinkler types, not repeated here.

Chapter 12 – Installation Requirements for Residential Sprinklers

12.1 General

12.1.7 Distances Between Sprinklers.

• 12.1.7.5: Two images removed, 12.1.7.5(a) and 12.1.7.5(b).
     

12.1.8 Deflector Position from Ceilings and Walls.

12.1.8.1.2(a) New Image: Position of sprinkler under beam

 

12.1.8.8 Deflector Orientation (Residential Sidewall Sprinklers). (New in 2025)

” Residential sidewall sprinklers, where installed under a sloped ceiling with a slope exceeding 2 in 12, shall be located in accordance with one of the following:”

• At the high point of the slope and positioned to discharge downward along the slope as shown in Figure 12.1.8.8(a)
• “Along slopes not exceeding 8 in 12 with the deflector installed parallel to the slope and positioned to discharge across the slope as shown in Figure 12.1.8.8(b)”

   

New Images: Figure 12.1.8.8(a) Sidewall Deflector Orientation with Discharge Parallel to the Slope & Figure 12.1.8.8(b) Sidewall Deflector Orientation with Discharge Perpendicular to the Slope.

12.1.10 Obstructions to Sprinkler Discharge (Residential Upright and Pendent Sprinklers).

12.1.10.3 Obstructions that Prevent Sprinkler Discharge from Reaching Hazard.

• 2022:
  • 12.1.10.3.1: Obstructions > 18 in below deflector that block water must be addressed under 12.1.10.3.
  • 12.1.10.3.2: Sprinklers required under fixed obstructions > 4 ft wide.
  • 12.1.10.3.3: Sprinklers under open gratings must be shielded.
• 2025:
  • 12.1.10.3 is now a single pointer:
    • “Continuous or noncontinuous obstructions that interrupt the water discharge in a horizontal plane more than 18 in. (450 mm) below the sprinkler deflector in a manner to limit the distribution from reaching the protected hazard shall comply with 9.5.5.3. (See A.‍9.5.5.3.1.)”

12.1.11 Residential Sidewall Obstructions

• 12.1.11.1.5 – Soffits and cabinets
  • 2022 title: “Soffits and Cabinets.”
  • 2025 title: “Soffits and Wall Cabinets.”

12.1.11.2 Pattern development obstructions

• 12.1.11.2.3 Shadow Areas for Residential Sidewalls (New in 2025)
  • “Shadow areas created by walls and partitions shall be permitted in the protection area of a sprinkler as long as the cumulative areas do not exceed 15 ft2 (1.4 m2) per sprinkler.”

12.1.11.3 Obstructions preventing discharge from reaching hazard

• 2022:
  • 12.1.11.3.1–3.5 detailed requirements:
    • Sprinklers under fixed obstructions > 4 ft.
    • Sprinklers under gratings shielded, etc.
• 2025:
  • One line: obstructions > 18 in below deflector that limit distribution must comply with 9.5.5.3 (see A.9.5.5.3.1).

Chapter 13 – Installation Requirements for CMSA Sprinklers

13.2 CMSA Sprinklers

13.2.1.2 Ceiling slope limit (New in 2025) “CMSA sprinklers shall be installed only in buildings where the roof or ceiling slope does not exceed 4 in 12.”

13.2.5 Sprinkler Spacing (CMSA Sprinklers)

13.2.5.4 Minimum Distance Between Sprinklers.

• 13.2.5.4.2 Channels in solid obstructed construction
  • “Where sprinklers are installed in every channel formed by solid obstructed construction with the deflectors above the bottom of the structural members, sprinklers in adjacent channels shall be permitted to be placed less than 8 ft (2.4 m) on center.”
  • 2022: No equivalent allowance. Minimum spacing 8 ft OC unless using baffles (13.2.6.4.1) or simply not possible.
  • 2025: If:
    • You have solid obstructed construction forming channels,
    • Sprinklers are installed in every channel, and
    • Deflectors are above the bottom of the structural members,

    Then you may go < 8 ft between sprinklers in adjacent channels, using the structural members as “natural baffles.

13.2.6 Deflector Position (CMSA Sprinklers).

13.2.6.1 Distance Below Ceilings:

• 2022:
  • Unobstructed: deflector 6–8 in below ceiling.
  • Obstructed: three options:
    • 6–12 in below ceiling.
    • For joists, etc.: within 1–6 in below joist bottom, up to 22 in to deck, with extra pressure under open wood joist.
    • For concrete tees: deflector at or above 1 in below tee stems, with tees <7′-6″ apart, >3 ft on centers, and “regardless of depth,” but must comply with CMSA obstruction table.
• 2025:
• 13.2.6.1.2 Obstructed construction
  • The obstructed rules have been expanded and segmented by ceiling slope, with an explicit note about “≤ 50% open” vs “> 50% open.”
  • Enhanced content clarifies:
    • These new rules are driven by FPRF sloped storage testing.
    • Obstructed construction covered here is limited to ≤ 50% open. If > 50% open, treat as “unobstructed” per 13.2.6.1.2.4.
  • 13.2.6.1.2.1 Obstructed Construction for Ceilings with Slopes Not Exceeding 1 in 12.

    “Where the slope of the ceiling does not exceed 1 in 12, the sprinkler deflector shall be located in accordance with one of the following arrangements:”

    • “Sprinklers shall be installed in each individual channel of obstructed construction with the deflectors located a minimum of 6 in. (150 mm) and a maximum of 12 in. (300 mm) below the ceiling/roof deck.”
    • “Where the maximum depth of the noncombustible structural members, including concrete tees, is 18 in. (450 mm), sprinkler deflectors shall be permitted to be installed within a horizontal plane not exceeding 6 in. (150 mm) vertically below the bottom of the noncombustible structural members.”
    • “Where the maximum depth of the noncombustible structural members, including concrete tees, is greater than 18 in. (450 mm) but does not exceed 24 in. (600 mm), sprinkler deflectors shall be permitted to be installed within a horizontal plane not exceeding 6 in. (150 mm) vertically below the bottom of the noncombustible structural members only when the channels formed by obstructed construction are provided with blocking to the full depth of the noncombustible structural member with material equivalent to the structural member’s construction so that individual channel volumes do not exceed 400 ft3 (11.3 m3).”
    • “Where wood joists or composite wood joists are provided with blocking to the full depth of the joists with material equivalent to or less combustible than the web construction so that individual channel volumes do not exceed 400 ft3 (11.3 m3), sprinkler deflectors shall be permitted to be installed within a horizontal plane not exceeding 6 in. (150 mm) vertically below the bottom of the joists only when a maximum distance of 22 in. (550 mm) can be maintained between the sprinkler deflector and the ceiling/roof deck.”
  • 13.2.6.1.2.2 Obstructed Construction Less than or Equal to 50 Percent Open for Ceilings with Slopes Not Exceeding 2 in 12.

    “Where the slope of the ceiling is greater than 1 in 12, but does not exceed 2 in 12, the sprinkler deflector shall be located in accordance with one of the following arrangements:”

    • “Sprinklers shall be installed in each individual channel of obstructed construction with the deflectors located a minimum of 6 in. (150 mm) and a maximum of 12 in. (300 mm) below the ceiling/roof deck.”
    • “Where the maximum depth of the noncombustible structural members, including concrete tees, is 12 in. (300 mm), sprinkler deflectors shall be permitted to be installed within a horizontal plane not exceeding 6 in. (150 mm) vertically below the bottom of the noncombustible structural members.”
    • “Where the maximum depth of the noncombustible structural members, including concrete tees, is greater than 12 in. (300 mm) but does not exceed 24 in. (600 mm), sprinkler deflectors shall be permitted to be installed within a horizontal plane not exceeding 6 in. (150 mm) vertically below the bottom of the noncombustible structural members only when the channels formed by obstructed construction are provided with blocking to the full depth of the noncombustible structural member with material equivalent to the structural member’s construction so that individual channel volumes do not exceed 400 ft3 (11.3 m3).”
    • “Where wood joists or composite wood joists are provided with blocking to the full depth of the joists with material equivalent to or less combustible than the web construction so that individual channel volumes do not exceed 400 ft3 (11.3 m3), sprinkler deflectors shall be permitted to be installed within a horizontal plane not exceeding 6 in. (150 mm) vertically below the bottom of the joists only when a maximum distance of 22 in. (550 mm) can be maintained between the sprinkler deflector and the ceiling/roof deck.”
  • 13.2.6.1.2.3 Obstructed Construction Less than or Equal to 50 Percent Open for Ceilings with Slopes Not Exceeding 4 in 12.

    “Where the slope of the ceiling is greater than 2 in 12, but does not exceed 4 in 12, the sprinkler deflector shall be located in accordance with one of the following arrangements:”

    • “Sprinklers shall be installed in each individual channel of obstructed construction with the deflectors located a minimum of 6 in. (150 mm) and a maximum of 12 in. (300 mm) below the ceiling/roof deck.”
    • “Where the maximum depth of the structural members, including concrete tees, is 12 in. (300 mm) and are installed perpendicular to the ceiling slope, sprinkler deflectors shall be permitted to be installed within a horizontal plane not exceeding 6 in. (150 mm) vertically below the bottom of the structural members only when the channels formed by obstructed construction are provided with blocking to the full depth of the structural member with material equivalent to or less combustible than the structural member’s construction so that individual channel volumes do not exceed 300 ft3 (8.5 m3).”
  • 13.2.6.1.2.4 Obstructed Construction Greater than 50 Percent Open.

    “Where the slope of the ceiling is greater than 1 in 12 under obstructed construction that is greater than 50 percent open, sprinklers shall be installed in accordance with the rules for unobstructed construction.”

13.2.7 Obstructions to Sprinkler Discharge (CMSA Sprinklers).

• 2022 (13.2.8):
  • Had its own CMSA-specific obstruction framework, including:
    • Table 13.2.8.1.2(a)/(b) (allowable distance above/beside obstructions).
    • 36 in “pattern development” zone below sprinklers where obstructions must be evaluated.
    • Three-times-rule for obstructions ≤8 in wide.
    • Special rules for branch lines (sprinklers directly on branch lines ≤4 in diameter vs sprigs/offsets for >4 in).
    • Tables 13.2.8.3.2(a)/(b) for obstructions entirely below sprinklers, with required A/B distances.
    • Specific diagrams for obstructions 24 in below, more than 24 in below, parallel to branch lines, etc.
• 2025:
  • 13.2.7.1 General
    • 13.2.7.1.1: “In addition to the requirements of 9.5.5, CMSA sprinklers shall be arranged in accordance with 13.2.7 to minimize obstruction to their discharge pattern, or supplemental sprinklers shall be provided to ensure adequate coverage of the hazard.”
    • 13.2.7.1.2: “CMSA sprinklers with a special obstruction allowance shall be installed according to their listing.”
  • 13.2.7.2 Obstructions to pattern development
    • 13.2.7.2.1: “In addition to the requirements of 13.2.7.2.2, CMSA sprinklers shall be arranged in accordance with 14.2.10.2 to minimize obstruction to the development of their discharge pattern.”
    • 13.2.7.2.2: “Unless the requirements of 14.2.10.2 are met, for obstructions 8 in. (200 mm) wide or less in width, as shown in Figure 13.2.7.2.2, sprinklers shall be positioned such that they are located at least a distance three times greater than the maximum dimension of the obstruction from the sprinkler.”
  • 13.2.7.3 Obstructions that prevent discharge from reaching hazard
    • “CMSA sprinklers shall be arranged in accordance with 14.2.10.3 to minimize obstruction to sprinkler discharge reaching the hazard. (See A.‍9.5.5.3.1.)”
    • Major structural change; many 2022 CMSA-only obstruction rules are removed from Chapter 13 and replaced with cross-references to the ESFR obstruction framework in Chapter 14 plus the three-times rule.

13.2.8 Clearance to storage (was 13.2.9)

Chapter 14 – Installation Requirements for Early Suppression Fast-Response Sprinklers

14.2 Early Suppression Fast-Response Sprinklers

14.2.3 Roof / Ceiling Slope Limit

2022:

• ESFR sprinklers permitted only where roof or ceiling slope does not exceed 2 in 12.

2025:

• ESFR sprinklers permitted where roof or ceiling slope does not exceed 4 in 12.

14.2.6 Occupancy and Hazard (2022 Origin 14.2.7)

2022:

• ESFR permitted in light and ordinary hazard occupancies if listed.
• Additional allowances:
  • 14.2.7.2: Protection area permitted to follow Ch. 10.
  • 14.2.7.3: Spacing permitted to follow Ch. 10.
  • 14.2.7.4: Obstruction rules permitted to follow 10.2.7.2.

2025:

• 14.2.6.1: “When ESFR sprinklers are used for the protection of light or ordinary hazard occupancies, the obstruction to the sprinkler discharge pattern of ESFR sprinklers shall be permitted to meet the obstruction discharge requirements of 10.2.8.2.”

14.2.7 Protection Areas per Sprinkler (2022 Origin 14.2.8)

14.2.7.2 Maximum Protection Area of Coverage.

14.2.7.2.3 Sprinkler Movement to Avoid Obstructions (2022 Origin 14.2.8.2.3 & 14.2.8.2.4)

• 2022 14.2.8.2.3* (Moving an individual sprinkler)
  • Applies where obstructions created by structural elements (e.g., trusses, bar joists, wind bracing) interfere with sprinkler placement.
  • A single sprinkler may be moved along the branch line up to 1 ft (300 mm) from its allowable spacing.
  • Coverage of the moved sprinkler ≤ 110 ft².
  • Average actual floor area of the moved sprinkler and adjacent sprinklers ≤ 100 ft².
  • Adjacent branch lines must maintain the same pattern.
  • Maximum distance between sprinklers ≤ 12 ft.
• 2022 14.2.8.2.4 (Moving an entire branch line)
  • Same obstruction basis as 14.2.8.2.3 (structural elements).
  • One entire branch line may be moved up to 1 ft (300 mm) from its allowable spacing.
  • Coverage for sprinklers on the moved branch line and the adjacent branch line ≤ 110 ft² per sprinkler.
  • Average actual floor area ≤ 100 ft².
  • Maximum distance between sprinklers ≤ 12 ft.
  • Branch lines cannot be moved if there are already moved sprinklers that exceed maximum spacing.
• 2025:
  • “Where obstructions that prevent sprinkler discharge from reaching the hazard exist, ceiling sprinklers shall be permitted to exceed their maximum allowable spacing to avoid these obstructions as follows:”
    1. “The linear spacing of the obstructed sprinkler, in the direction the sprinkler is moved, shall not exceed 1 ft (0.3 m) beyond the maximum allowable linear spacing.”
    2. “The linear spacing of the obstructed sprinkler, in the direction the sprinkler is moved, shall not exceed 12 ft (3.7 m).”
    3. “The area of coverage of the obstructed sprinkler shall not exceed 110 ft2 (10 m2).”
    4. “Where the obstructed sprinkler has been moved in a direction along the branch line, the linear and area spacing of the sprinklers on either side of the obstructed sprinkler along the branch line shall comply with the allowable sprinkler spacing requirements.”
    5. “Where the obstructed sprinkler has been moved in a direction between the branch lines, the linear spacing and area of coverage of the sprinklers on either side of the obstructed sprinkler between the branch lines shall comply with the allowable sprinkler spacing requirements.”
  • Applies where obstructions prevent sprinkler discharge from reaching the hazard.
  • Not limited to “structural elements” language; framed around discharge effectiveness.
  • A ceiling sprinkler may exceed maximum allowable spacing to avoid the obstruction.
  • Linear spacing in the direction of movement:
    • ≤ 1 ft beyond maximum allowable spacing.
    • ≤ 12 ft total.
  • Coverage of the obstructed sprinkler ≤ 110 ft².
  • No average-area requirement stated.
  • Compliance depends on direction of movement:
    • Along branch line: sprinklers on either side along the branch line must comply.
    • Between branch lines: sprinklers on either side between branch lines must comply.

14.2.8 Sprinkler Spacing (2022 Origin 14.2.9)

14.2.8.4.3 Structural Members Acting as Baffles (New in 2025)

2022:

• Channelized construction rules scattered across 14.2.4 and 14.2.9.
• Structural members implicitly treated as separators.

2025:

• “Where sprinklers are installed in every channel formed by solid obstructed construction with the deflectors above the bottom of the structural members, the structural members shall be considered baffles in accordance with 14.2.8.4.2.”

14.2.9 Deflector Position (Early Suppression Fast-Response Sprinklers).

14.2.9.1 Distance Below Ceilings. (K-factor based distance below ceiling)

2022:

• 14.2.10.1.1: Pendent K-14 / K-16.8 / K-28: 6–14 in.
• 14.2.10.1.2: Pendent K-22.4 / K-25.2 / K-33.6: 6–18 in.
• 14.2.10.1.3: Upright K-14 / K-16.8: 3–12 in.
• 14.2.10.1.4: With obstructed construction, branch lines permitted across beams, but sprinklers in bays, not under beams.

2025:

• 14.2.9.1.1 Unobstructed construction
  • “Where nominal K-14.0 (K-200), K-16.8 (K-240), and K-28.0 (K-400) pendent sprinklers are installed under unobstructed construction, the deflectors shall be positioned a minimum 6 in. (150 mm) and a maximum of 14 in. (350 mm) below the ceiling/roof deck.”
  • “Where nominal K-22.4 (K-320), K-25.2 (K-360), and K-33.6 (K-480) pendent sprinklers are installed under unobstructed construction, the deflectors shall be positioned a minimum 6 in. (150 mm) and a maximum of 18 in. (450 mm) below the ceiling/roof deck.”
  • “Where nominal K-14.0 (K-200) and K-16.8 (K-240) upright sprinklers are installed under unobstructed construction, the deflectors shall be positioned a minimum of 3 in. (75 mm) and a maximum of 12 in. (300 mm) below the ceiling/roof deck.”
• 14.2.9.1.2 Obstructed construction
  • 2025 turns the “obstructed construction” deflector positioning into a decision tree; it introduces a structured, conditional framework allowing alternate deflector planes depending on:
    • percent open (≤ 50% open vs > 50% open),
    • ceiling slope bands (≤1:12, >1:12–≤2:12, >2:12–≤4:12),
    • structural member depth thresholds (12 in / 18 in / 24 in),
    • blocking and channel volume caps (400 ft³ for some cases; 300 ft³ for the steeper/specific orientation case),
    • member orientation (perpendicular to slope in the 4:12 case).
  • 14.2.9.1.2.1 Obstructed Construction Less than or Equal to 50 Percent Open for Ceilings with Slopes Not Exceeding 1 in 12.

    “Where the slope of the ceiling does not exceed 1 in 12, the sprinkler deflector shall be located in accordance with one of the following arrangements:”

    1. “Sprinklers shall be installed in each individual channel of obstructed construction with the deflectors located below the ceiling/roof deck in accordance with 14.2.9.1.1.”
    2. “Where the maximum depth of the structural members, including concrete tees, is 18 in. (450 mm), sprinkler deflectors shall be permitted to be installed within a horizontal plane not exceeding 6 in. (150 mm) vertically below the bottom of the structural members.”
    3. “Where the maximum depth of the structural members, including concrete tees, is greater than 18 in. (450 mm) but does not exceed 24 in. (600 mm), sprinkler deflectors shall be permitted to be installed within a horizontal plane not exceeding 6 in. (150 mm) vertically below the bottom of the structural members only when the channels formed by obstructed construction are provided with blocking to the full depth of the structural member with material equivalent to or less combustible than the structural member’s construction so that individual channel volumes do not exceed 400 ft3 (11.3 m3).”
• 14.2.9.1.2.2 Obstructed Construction Less than or Equal to 50 Percent Open for Ceilings with Slopes Not Exceeding 2 in 12.

  “Where the slope of the ceiling is greater than 1 in 12, but does not exceed 2 in 12, the sprinkler deflector shall be located in accordance with one of the following arrangements:”

  1. “Sprinklers shall be installed in each individual channel of obstructed construction with the deflectors located below the ceiling/roof deck in accordance with 14.2.9.1.1.”
  2. “Where the maximum depth of the structural members, including concrete tees, is 12 in. (300 mm), sprinkler deflectors shall be permitted to be installed within a horizontal plane not exceeding 6 in. (150 mm) vertically below the bottom of the structural members.”
  3. “Where the maximum depth of the structural members, including concrete tees, is greater than 12 in. (300 mm) but does not exceed 24 in. (600 mm), sprinkler deflectors shall be permitted to be installed within a horizontal plane not exceeding 6 in. (150 mm) vertically below the bottom of the structural members only when the channels formed by obstructed construction are provided with blocking to the full depth of the structural member with material equivalent to or less combustible than the structural member’s construction so that individual channel volumes do not exceed 400 ft3 (11.3 m3).”
• 14.2.9.1.2.3 Obstructed Construction Less than or Equal to 50 Percent Open for Ceilings with Slopes Not Exceeding 4 in 12.
  • “Where the slope of the ceiling is greater than 2 in 12, but does not exceed 4 in 12, the sprinkler deflector shall be located in accordance with one of the following arrangements:”
    1. “Sprinklers shall be installed in each individual channel of obstructed construction with the deflectors located below the ceiling/roof deck in accordance with 14.2.9.1.1.”
    2. “Where the maximum depth of the structural members, including concrete tees, is 12 in. (300 mm) and the structural members are installed perpendicular to the ceiling slope, sprinkler deflectors shall be permitted to be installed within a horizontal plane not exceeding 6 in. (150 mm) vertically below the bottom of the structural members only when the channels formed by obstructed construction are provided with blocking to the full depth of the structural member with material equivalent to or less combustible than the structural member’s construction so that individual channel volumes do not exceed 300 ft3 (8.5 m3).”
• 14.2.9.1.2.4 Obstructed Construction Greater than 50 Percent Open.
  • “Where the slope of the ceiling is greater than 1 in 12 under obstructed construction that is greater than 50 percent open, sprinklers shall be installed in accordance with the rules for unobstructed construction.”

14.2.9.2 Deflector orientation

2022:

• “Deflectors … aligned parallel to ceilings or roofs.”

2025:

• “Deflectors … aligned in accordance with 9.5.4.3.”

14.2.10 Obstructions to Sprinkler Discharge (Early Suppression Fast-Response). (2022 Origin 14.2.11)

14.2.10.1 General (2025)

• 2022 equivalent:
  • The “obstruction rules” were primarily in 14.2.11, but the “high-piled adjacency trigger” was in a different place:
  • 14.2.11.2(8): apply obstruction criteria (there, 14.2.11.2) to ceiling sprinklers within 6 ft horizontally of any high-piled storage (same “not physically separated” condition).
  • Also, 2022 repeated “special obstruction allowance per listing” in multiple sub-sections: 14.2.11.1.3, 14.2.11.2(6), 14.2.11.3.7.
• 2025:
  • 14.2.10.1.1 Adds: “In addition to the requirements of 9.5.5, ESFR sprinklers shall be arranged in accordance with 14.2.10 to minimize obstruction to their discharge pattern, or supplemental sprinklers shall be provided to ensure adequate coverage of the hazard.”
  • 14.2.10.1.2 (2022 Origin 14.2.11.1.3): “ESFR sprinklers with a special obstruction allowance shall be installed according to their listing.”
  • 14.2.10.1.3 (2022 Origin 14.2.11.2(8)): “Where high-piled storage is not physically separated from an adjacent light or ordinary hazard area, the sprinkler obstruction criteria of 14.2.10 shall apply to all ceiling sprinklers located within 15 ft (4.6 m) horizontally of any high-piled storage.”

14.2.10.2 Obstructions to Sprinkler Discharge Pattern Development (2025)

• 2022 equivalent 14.2.11.1.2: only covered the <24 in obstruction condition. “The requirements of 14.2.11.1.1 shall not apply where sprinklers are spaced on opposite sides of obstructions less than 24 in. (600 mm) wide, provided the distance from the centerline on the obstructions to the sprinklers does not exceed one-half the allowable distance between sprinklers.”
• 2025:
  • Added condition number 2 for the exception of table rules. Table rules do not apply where one of the following conditions is satisfied:
    1. “Sprinklers are spaced on opposite sides of an obstruction less than 24 in. (600 mm) wide, provided the distance from the centerline of the obstruction to the sprinklers does not exceed one-half the allowable distance between sprinklers.”
    2. “Supplemental sprinklers have been installed under the obstruction.”

14.2.10.2.3 Sprinkler Pipe

2022 equivalent: 14.2.11.3.3 Branchlines

• Same structure, except the horizontal offset was min 12 in (not 6 in) from the pipe.

2025:

• “Offset horizontally a minimum of 6 in. (150 mm) from the sprinkler pipe”

14.2.10.3 Obstructions that Prevent Sprinkler Discharge from Reaching Hazard

14.2.10.3.1 (New in 2025)

• Obstructions, continuous or noncontinuous, individual or grouped, that interrupt the water discharge in a horizontal plane below the sprinkler deflector in a manner to limit the distribution from reaching the protected hazard shall comply with 14.2.10.3.

14.2.10.3.2 (2022 equivalent 14.2.11.3.4)

14.2.10.3.3 (New in 2025)

• Supplemental sprinklers shall be installed under obstructions entirely below ceiling sprinklers where obstruction interferes with discharge reaching hazard.

14.2.10.3.4 When supplemental sprinklers NOT required

2025:

• “Supplemental sprinklers shall not be required below obstructions when the obstruction or occupancy is in accordance with one of the following:”
• “The obstruction is 11⁄2 in. (38 mm) or less in width and is located a minimum of 12 in. (300 mm) below the elevation of the sprinkler deflector.” (2022 equivalent 14.2.11.3.1(2))
• “The obstruction is 6 in. (150 mm) or less in width and is located a minimum of 6 in. (150 mm) horizontally from the sprinkler.” (2022 equivalent 14.2.11.3.1(3))
• “The obstruction is 24 in. (600 mm) or less in width and is located a minimum of 12 in. (300 mm) horizontally from the sprinkler.” (2022 equivalent 14.2.11.3.1(4))
• “The obstruction is 4 in. (100 mm) or less in width, and is located entirely below the sprinkler pipe connected to the ceiling sprinkler, and the ceiling sprinkler is upright.” (New in 2025)
• “The occupancy is protected in accordance with 14.2.6, and obstructions comply with 9.5.5.3.” (2022 equivalent 14.2.11.3.1(6))

14.2.10.3.5 Supplemental sprinkler spacing (2025)

14.2.10.3.5.1 (New in 2025)

• “When supplemental sprinklers are required, in addition to the requirements of 9.5.5.3.3 the spacing of supplemental sprinklers under obstructions shall be in accordance with one of the following:”
• “Where supplemental sprinklers are required below non-flat or non-solid obstructions, the sprinklers shall be located no more than 2 ft (0.6 m) horizontally from the edges of the obstruction and be installed using linear and area spacing that does not exceed 4 ft (1.2 m) and 16 ft2 (1.5 m2), respectively.”
• “Where supplemental sprinklers are required below flat, solid obstructions not exceeding 2 ft (0.6 m) in width, the maximum allowable linear spacing for the sprinklers shall be 8 ft (2.4 m).”
• “Where a flat, solid continuous horizontal barrier having the same footprint of the obstruction is installed below an obstruction not exceeding 2 ft (0.6 m) in width, the maximum allowable linear spacing for the sprinklers shall be 8 ft (2.4 m).”
• “Where supplemental sprinklers are required below flat, solid obstructions greater than 2 ft (0.6 m), but not exceeding 10 ft (3.0 m) in width, the maximum allowable linear spacing for the sprinklers shall be 10 ft (3.0 m).”
• “Where a flat, solid continuous horizontal barrier having the same footprint of the obstruction is installed below an obstruction greater than 2 ft (0.6 m), but not exceeding 10 ft (3.0 m) in width, the maximum allowable linear spacing for the sprinklers shall be 10 ft (3.0 m).”
• “Where supplemental sprinklers are required below flat, solid obstructions greater than 10 ft (3.0 m) in width, the supplemental sprinkler spacing shall be in accordance with the sprinkler’s spacing requirements for when the sprinkler is installed under unobstructed construction.”
• “Where a flat, solid continuous horizontal barrier having the same footprint of the obstruction is installed below an obstruction greater than 10 ft (3.0 m) in width, the supplemental sprinkler spacing shall be in accordance with the sprinkler’s spacing requirements for when the sprinkler is installed under unobstructed construction.”

14.2.10.3.5.2 (New in 2025)

• “When supplemental sprinklers are installed in accordance with 14.2.10.3.5.1, supplemental sprinklers shall not be required to be equipped with water shields.”

Chapter 15 – Installation Requirements for Special Sprinklers

15.1 Open Sprinklers and Open Nozzles

2022:

• Title: “Open Sprinklers”

2025:

• Title expanded to “Open Sprinklers and Open Nozzles”

15.1.3 (New in 2025)

• Where open sprinklers or open nozzles are used and automatic activation is achieved by hydraulic, pneumatic, or other means, the deflector of the open sprinklers or nozzles shall be permitted to exceed the maximum distance below the ceiling indicated in the applicable section for that style of sprinkler.

15.2 Special Sprinklers

15.2.1 Listing and Evaluation Criteria

• 2022:
  • Special sprinklers that are intended for the protection of specific hazards or construction features shall be permitted where such devices have been evaluated and listed for performance under the following conditions:
    1. Fire tests
    2. Spray pattern wetting (floors/walls)
    3. Obstructions
    4. Thermal sensitivity
    5. Performance under horizontal or sloped ceilings
    6. Area of design
    7. Allowable clearance to ceilings

• 2025
  • Special sprinklers that are intended for the protection of specific hazards or construction features shall be permitted where such devices have been evaluated and listed for performance under the following conditions:
    1. Fire tests
    2. Spray pattern wetting (floors/walls)
    3. Obstructions
    4. Thermal sensitivity
    5. Performance under horizontal or sloped ceilings
    6. Hydraulic design criteria (replaces “area of design”)
    7. Allowable clearance to ceilings

15.2 Special Sprinklers

15.2.3 Manufacturer’s Listing Basis (New in 2025)

• “Where special sprinklers are listed for protection of features, system design shall be based on the listing requirements identified in the manufacturer’s instructions for the individual sprinkler being used, unless otherwise approved.”

15.2.4 Equivalent Protection Schemes (New in 2025)

• “Listed sprinklers that have been tested at an approved testing laboratory for specific special use conditions as indicated in 15.2.1(1) through 15.2.1(7) as applicable shall be permitted to be used for equivalent fire protection schemes developed in accordance with Section 1.5 where acceptable to the AHJ.”
• Annex: “The development and use of test data to evaluate special use conditions at an approved testing laboratory that evaluate the performance of listed sprinklers under special use conditions can be used as a basis to demonstrate the equivalency of a proposed usage.”

Chapter 16 – Installation of Piping, Valves, and Appurtenances

16.1 Basic Requirements

16.1.3 Reconditioned Components

• 2022: “The use of reconditioned valves and devices shall not be permitted in new systems.”
• 2025: “The use of reconditioned valves and devices shall not be permitted in new systems.”

16.2 Sprinkler Installation

16.2.7 Stock of Spare Sprinklers.

• 16.2.7.1:
  • Annex adds: “It is the intent of this section to require spare sprinklers and associated manufacturer’s sprinkler wrenches based on the facility as opposed to individual buildings or systems. Spare sprinklers for campus arrangements such as schools, hospitals, or multifamily complexes should be located under the owner’s control and are not necessarily required to be provided at each building or riser location. A sufficiently sized cabinet(s) capable of meeting the requirements for a single building is adequate. The spare sprinkler cabinet should contain all the various types found on the property based on in the quantities prescribed in Chapter 16.”
• 16.2.7.2:
  • 2022: “The sprinklers shall correspond to the types and temperature ratings of the sprinklers in the property.”
  • 2025: “The sprinklers shall correspond to the types, orientations, and temperature ratings of the sprinklers in the property.”
• 16.2.7.5:
  • 2022: “The stock of spare sprinklers shall include all types, orientations, and ratings installed and shall be as follows:”
  • 2025: “The stock of spare sprinklers shall include all types, orientations, and ratings installed and shall be as follows:”
• 16.2.7.7: “A list of the sprinklers installed in the property shall be posted in the sprinkler cabinet.”
  • 2022:
    1. Sprinkler Identification Number (SIN) if equipped; or the manufacturer, model, K-factor, deflector type, thermal sensitivity, and pressure rating
    2. General description
    3. Quantity of each type to be contained in the cabinet
    4. Issue or revision date of the list
  • 2025:
    1. Sprinkler identification number (SIN), if equipped, the manufacturer, model, K-factor, deflector type, thermal sensitivity, pressure rating, and temperature rating
    2. Manufacturer’s sprinkler wrench model number for each sprinkler type
    3. General description
    4. Quantity of each type of sprinkler installed in the property
    5. Quantity of each type of sprinkler to be contained in the cabinet
    6. Issue or revision date of the list

16.3 Piping Installation

16.3.1 General

• 2022: Material-by-material routing statement (Steel per 16.3.2/3/4; Copper per 16.3.5; Nonmetallic per 16.3.9; Brass per 16.3.6; Stainless per 16.3.7).
• 2025: 16.3.1 replaces that with one broad sentence: “Sprinkler piping shall comply with the requirements of this section.”

16.3.2* Steel Pipe – Welded or Roll-Grooved

16.3.2.1 (New in 2025)

• “Black and galvanized pipe sizes shall be no less than 1 in. (25 mm) nominal.”

16.3.2.2 (2022 Renumbered 16.3.2)

16.3.3 Steel Pipe – Threaded.

• 16.3.3.1 (NEW in 2025)
  • “Black and galvanized pipes sizes shall be no less than 1 in. (25 mm) nominal.”
• 16.3.3.2 (2022 Renumbered 16.3.3)

16.3.4 Nonmetallic Pipe (New in 2025)

• 16.3.4.1: “Nonmetallic pipe shall be in accordance with 16.3.10.”
• 16.3.4.2: “Nonmetallic pipe shall be no less than 3/4 in. (20 mm) nominal.”

16.3.6 Copper Tube

• 16.3.6.1 (New in 2025): “Copper tube shall be no less than 3⁄4 in. (20 mm) nominal.”
• 16.3.6.2 (2022 Renumbered 16.3.5)

16.3.7 Brass Pipe

• 16.3.7.1 (New in 2025): “Brass pipe shall be no less than 3⁄4 in. (20 mm) nominal.”
• 16.3.7.2 (2022 Renumbered 16.3.6)

16.3.8 Stainless Steel Pipe

Status: Modified (new minimum nominal size rule + renumbered schedule rule).

• 16.3.8.1 (New in 2025): Stainless steel pipe shall be no less than 3⁄4 in. (20 mm) nominal.
• 16.3.8.2 (2022 Renumbered 16.3.7)

16.3.9 Metallic Pipe and Tube Bending

• 16.3.9.2:
  • 2022 (16.3.8.2): “For Schedule 40 and copper tubing…”
  • 2025: “For Schedule 40 steel pipe and Types K and L copper tubing…” This is largely clarifying, not changing the engineering intent.

16.3.13 Piping to Sprinklers Below Ceilings

Status: Modified (scope narrowed + renumbered).

2022 (16.3.12.1):

• “In new installations expected to supply sprinklers below a ceiling, minimum 1 in. (25 mm) outlets shall be provided.”

2025:

• “In new installations expected to supply sprinklers below a ceiling utilizing black or galvanized steel piping, minimum 1 in. (25 mm) outlets shall be provided.”

16.4 Protection of Piping

16.4.1 Protection of Piping Against Freezing

16.4.1.1.1*

• 2022: “The weather temperature used to determine if an unheated portion of a system is subject to freezing and required to be protected in accordance with 16.4.1.1 shall be the lowest mean temperature for one day, obtained from an approved source.”
• 2025: “The weather temperature used to determine if a portion of a system is subject to freezing and required to be protected in accordance with 16.4.1.1 shall be the average annual extreme minimum temperature, obtained from an approved source.”

16.4.2 Protection of Piping Against Corrosion

2022:

• 16.4.2.1: corrosive conditions → corrosion-resistant materials or protective coating
• 16.4.2.2: unusual corrosive properties → CRR ≥ 1 and treat per 5.1.4
• 16.4.2.3: corrosive conditions or weather exposure → corrosion-resistant materials/coatings
• 16.4.2.4: underground steel pipe → protect against corrosion

2025:

• 16.4.2.1: same basic “corrosive conditions” rule (plus new commentary about oceanfront salt spray; and reminder coatings not allowed on sprinklers in field)
• 16.4.2.2 (2022 Renumbered 16.4.2.3)
• 16.4.2.3 (2022 Renumbered 16.4.2.4)
• 16.4.2.4 (New in 2025): “Where conditions that contribute to MIC are found or known to exist, the owner(s) shall notify the sprinkler system installer and develop a plan to treat the system using one of the following methods:”
  • “Install system piping that will not be affected by the MIC microbes.”
  • “Treat all water that enters the system using a listed bacterial inhibitor.”
  • “Implement an approved plan for monitoring the interior conditions of the pipe at established time intervals and locations.”
  • “Install a corrosion monitoring station and monitor at established intervals”
• 16.4.2.5 (New in 2025): “Where conditions are found or are known to exist that contribute to unusual corrosive properties, the owner(s) shall notify the sprinkler system installer, and a plan shall be developed to treat the system using at least one of the following methods:”
  • “Install system piping that is corrosion resistant.”
  • “Treat water that enters the system using a listed corrosion inhibitor.”
  • “Implement an approved plan for monitoring the interior conditions of the pipe at established intervals and locations.”
  • “Install approved corrosion monitoring stations and monitor at established intervals.”
  • “Fill dry-pipe or preaction systems with at least 98 percent pure nitrogen in lieu of air to mitigate against corrosion.”
  • “Use a listed nitrogen generator that is sized and installed in accordance with the manufacturer’s instructions.”
  • “Use a listed vapor corrosion inhibitor delivery system sized and installed in accordance with the manufacturer’s instructions.”
• 16.4.2.6 (2022 Renumbered 16.4.2.2).

16.4.4 Protection of Piping Subject to Mechanical Damage

Status: Modified (expanded scope + new plate extension requirement).

2022:

• Applied when pipe other than steel run horizontally or vertically through wood or metal studs, with shield plates when pipe face < 1.25 in. from edge; plate thickness; cover notched/bored area.

2025:

• “Where concealed pipe other than steel is installed through holes or notches in studs, joists, rafters, or similar members less than 1.25 in. (32 mm) from the nearest edge of the member, the following provisions shall apply:”
• Keeps plate thickness and “cover the area” requirement.
• Adds “(4) Steel shield plates shall extend a minimum of 2 in. (50 mm) along the member.”
  • Annex: “Nail plates should only cover the stud or structural member that the pipe is penetrating — the nail plate should not extend past the width of the member. Only the length of the nail plate along the member should be extended a minimum of 2 in. (50 mm).”

16.8 Fitting Installation

16.8.8 Flexible Sprinkler Hose Fitting Length (New in 2025)

• 16.8.8.1:
  • “Flexible sprinkler hose fittings shall not exceed 12 ft (3.7 m) in length when installed above a rigid ceiling.”
  • Annex: “Rigid ceilings are ceilings that could include cleanroom ceiling structures, freezers, steel, concrete, masonry, wood, gypsum board, or similar rigid materials. These ceilings typically have a penetration for the sprinkler, and it would be difficult to inappropriately relocate the sprinkler.”
• 16.8.8.2:
  • “Flexible sprinkler hose fittings shall not exceed 6 ft (1.8 m) in length when installed above an acoustical tile and lay-in panel ceiling.”

16.9 Valves

16.9.4 Check Valves.

• 16.9.4.1
  • 2022: “Where there is more than one source of water supply, a check valve shall be installed in each connection.”
  • 2025: “Where a fire department connection is installed or there is more than one source of water supply, a check valve shall be installed in each connection.”
• 16.9.4.3 (Removed in 2025):
  • “Where cushion tanks are used with automatic fire pumps, no check valve is required in the cushion tank connection.”

16.10 Drainage

16.10.3 Dry Pipe and Preaction Systems

16.10.3.1 Dry Pipe and Preaction Systems in Nonrefrigerated Areas

• 2022:
  • 16.10.3.1 Dry Pipe Systems in Nonrefrigerated Areas.
    • branch 1/2 in per 10 ft; mains 1/4 in per 10 ft
  • 16.10.3.2 Preaction Systems: same numerical values.
• 2025: combines them into one rule.
  • Branch lines shall be pitched at least 1⁄2 in. per 10 ft (4 mm/m), and mains shall be pitched at least 1⁄4 in. per 10 ft (2 mm/m) in nonrefrigerated areas.
• 16.10.3.2 Dry Pipe and Preaction Systems in Refrigerated Areas (2022 Renumbered 16.10.3.3).

16.10.4 System, Main Drain, or Sectional Drain Connections

16.10.4.2*

• 2022: “Drain connections for system supply risers and mains shall be sized as shown in Table 16.10.4.2.”
• 2025: “Main drain test connections for system risers mains shall be sized as shown in Table 16.10.4.2.”

16.10.5 Auxiliary Drains

• 16.10.5.3 Auxiliary Drains for Dry Pipe Systems and Preaction Systems in Areas Subject to Freezing.
  • Title used to be: “Auxiliary Drains for Dry Pipe Systems and Preaction Systems.”

16.11 System Attachments

16.11.1 Attachments – General

16.11.1.3 Documentation Cabinet (New in 2025)

• 16.11.1.3.1 “A documentation cabinet shall be installed at an approved location at the protected premises.”
• 16.11.1.3.2 “The documentation cabinet shall be sized so that it can contain all necessary documentation.”
• 16.11.1.3.3 “All record documentation shall be stored in the documentation cabinet in an electronic or hardcopy format.”
• 16.11.1.3.4 “The documentation cabinet shall contain at a minimum the final record of completion documents, final shop drawings, and as-builts of the fire sprinkler system.”

16.12 Fire Department Connections

16.12.3 Fire Department Connection Types

16.12.3.1 (primary standard reference)

• 2022: thread spec referenced NFPA 1963
• 2025: thread spec referenced NFPA 1960

16.12.3.1.1 (AHJ nonconforming connections)

• 2022: “do not conform to NFPA 1963”
• 2025: “do not conform to NFPA 1960”

16.12.3.1.3

• 2022: “A single-outlet fire department connection shall be acceptable where piped to a 3 in. (80 mm) or smaller riser.”
• 2025: “A single-inlet fire department connection shall be acceptable where piped to a 3 in. (80 mm) or smaller riser.”

16.13 Gauges

16.13.3

• 2022: “The required pressure gauges shall be approved and shall have a maximum limit not less than twice the normal system working pressure at the point where installed.”
• 2025: “The required pressure gauges shall be approved and shall have a maximum limit not less than one and a half times the normal system working pressure at the point where installed.”

16.14 Systems Connections

16.14.2 Dry Pipe Systems

16.14.2.1

• 2022: “A trip test connection or manifold not less than 1 in. (25 mm) in diameter, terminating in a smooth bore corrosion-resistant orifice, to provide a flow equivalent to one sprinkler of a type installed on the particular system, shall be installed.”
• 2025: “A trip test connection not less than 1 in. (25 mm) in diameter, terminating in a smooth bore corrosion-resistant orifice, to provide a flow equivalent to one sprinkler of a type installed on the system, shall be installed on each system, except as modified in 16.14.2.2 and 16.14.2.3.”

16.14.2.2 and 16.14.2.3 (simulation for 2 or 4 sprinklers) (New in 2025)

• “When the water delivery requirement has been determined in accordance with 8.2.4.3 or 8.2.4.4 for two sprinklers, the trip test connection shall be arranged to simulate two sprinklers on the most remote sprinkler branch line.”
• “When the water delivery requirement has been determined in accordance with 8.2.4.3 or 8.2.4.4 for four sprinklers, the trip test connection shall be arranged to simulate two sprinklers on the most remote sprinkler branch line and two sprinklers on the next adjacent branch line.”

16.14.2.4 (2022 Origin 16.14.2.2)

• 2022: “The trip test connection or manifold shall be located on the end of the most distant sprinkler pipe in the upper story and shall be equipped with an accessible shutoff valve and a plug not less than 1 in. (25 mm), of which at least one shall be brass.”
• 2025: “The trip test connection shall be located on the end of the most remote branch line(s) and be equipped with an accessible shutoff valve not less than 1 in. (25 mm) size.”

16.14.2.4.1 (New in 2025)

• “Disconnection of the trip test connection and plugging of the valve between test cycles shall be permitted.”

16.14.2.5 (pneumatic supervisory alarm test)

• 2022: pneumatic supervisory air testing content lived under 16.14.3 preaction (and 16.14.3.1-.2 addressed supervisory air).
• 2025: “The connection used to control the level of priming water or to remove excess water from above the clapper shall be considered adequate to test the operation of the alarms monitoring the supervisory pneumatic pressure.”

16.14.3 Preaction Systems

• 2022:
  • 16.14.3.1 “A test connection shall be provided on a preaction system using supervisory air.”
  • 16.14.3.2 “The connection used to control the level of priming water shall be considered adequate to test the operation of the alarms monitoring the supervisory air pressure.”
  • 16.14.3.3–16.14.3.7 detailed double interlock trip test connection/manifold requirements with remote location and plug/brass/nipple-cap, and simulation rules.
• 2025:
  • 16.14.3.1 “A trip test connection in accordance with 16.14.2 shall be installed on each double interlock and noninterlock preaction systems.”
  • 16.14.3.2 “The connection used to control the level of priming water or to remove excess water from above the clapper shall be considered adequate to test the operation of the alarms monitoring the supervisory pneumatic pressure.16.14.3.3 then again states (for double interlock) a “trip test connection or manifold…” requirement”

16.17 Signs

• 2022: 16.17 marked (Reserved).
• 2025: “A copy of the information from all required signage shall be kept in the documentation cabinet in an electronic and/or hardcopy format.”

Chapter 17 – Installation of Piping, Valves, and Appurtenances

17.2 Hanger Components

17.2.1 Hanger Rods

17.2.1.1 Table 17.2.1.1 (Hanger Rod Sizes)

The table adds Pipe Size 14, 16, 18, 20, and 24 inch in the 2025 version.

 

17.2.1.4 U-Hooks

 

17.2.1.5 Eye Rods

 

17.2.4 Fasteners in Wood.

Table 17.2.4.2.1 Screw Dimensions for Ceiling Flanges and U-Hooks

Remains similar but adds more options to the U-Hooks allowance of pipe size up to and including 2 inch.

 

17.3 Trapeze Hangers

17.3.2 (New in 2025): “Interpolation of the section modulus values in Table 17.3.1(a) and Table 17.3.1(b) shall not be permitted.”

17.5 Pipe Standards

17.5.4 Pipe Stand Base.

17.5.4.4:

• 2022: “A minimum of four anchors shall be used to attach the base plate to the floor.”
• 2025: “A minimum of four anchors shall be used to attach the base plate to the floor, unless the requirements of 17.5.4.4.1 are met.”

Chapter 18 – Installation Requirements for Seismic Protection

18.2 Flexible Couplings

18.2.2 (New in 2025):

• “A listed flexible coupling or fitting used for seismic protection shall allow axial displacement, rotation, and at least 1 degree of angular movement of the pipe without inducing harm on the pipe. For pipe diameters of 8 in. (200 mm) and larger, the angular movement is permitted to be less than 1 degree but not less than 0.5 degree.”

18.6 Restraint of Branch Lines

18.6.7

• 2022: “Drops and armovers shall not require restraint.”
• 2025: “Drops, armovers, and flexible sprinkler hose fittings shall not require restraint.”

Chapter 19 – Design Approaches

19.1 General

19.1.6 Hose Allowance.

19.1.6.4

• 2022: “For partially sprinklered buildings, the sprinkler demand, not including hose stream allowance, as indicated in Figure 19.2.3.1.1 shall be added to the requirements given in NFPA 14.”
• 2025: “For partially sprinklered buildings, the sprinkler demand, not including hose stream allowance, as indicated in Chapters 19 through 28 shall be added to the requirements given in NFPA 14.”

19.2 Occupancy Hazard Fire Control Approach for Spray Sprinklers

19.2.2 Water Demand Requirements – Pipe Schedule Method.

19.2.2.3

• 2022 permitted pipe schedule for:
  • Additions/modifications to existing pipe schedule systems
  • Additions/modifications to existing extra hazard pipe schedule systems
  • New systems ≤ 5000 ft²
  • New systems > 5000 ft² @ 50 psi at highest sprinkler
• 2025 permits pipe schedule ONLY for:
  • New systems ≤ 5000 ft²
  • New systems > 5000 ft² @ 50 psi

19.2.3 Water Demand Requirements – Hydraulic Calculation Methods.

19.2.3.1 General

19.2.3.1.1

• 2022 allowed:
  • Single-point density/area (new systems)
  • Density/area curves (existing systems)
  • Room design method
  • Special design areas
• 2025 allows ONLY:
  • Single-point density/area (Table 19.2.3.1.1)
  • Room design method
  • Special design areas

19.2.3.1.5 Unsprinklered Combustible Concealed Spaces.

19.2.3.1.5.2 “The following unsprinklered concealed spaces shall not require a minimum area of sprinkler operation of 3000 ft2 (280 m2):”

• 2022:
  • (5) Concealed spaces where rigid materials are used and the exposed surfaces comply with one of the following in the form in which they are installed in the space:
    • (a) The surface materials have a flame spread index of 25 or less and the materials have been demonstrated to not propagate fire more than 10.5 ft (3.2 m) when tested in accordance with ASTM E84, Standard Test Method for Surface Burning Characteristics of Building Materials, or UL 723, Standard for Test for Surface Burning Characteristics of Building Materials, extended for an additional 20 minutes in the form in which they are installed in the space
  • (8) Vertical pipe chases under 10 ft2 (0.9 m2), provided that in multifloor buildings the chases are firestopped at each floor using materials equivalent to the floor construction and pipe penetrations at each floor are properly sealed, and where such pipe chases contain no sources of ignition, and piping is noncombustible
  • (10) Light or ordinary hazard occupancies where noncombustible or limited-combustible ceilings are attached to the bottom of composite wood joists either directly or on to metal channels not exceeding 1 in. (25 mm) in depth, provided the adjacent joist channels are firestopped into volumes not exceeding 160 ft3 (4.5 m3) using materials equivalent to 1⁄2 in. (13 mm) gypsum board, and at least 31⁄2 in. (90 mm) of batt insulation is installed at the bottom of the joist channels when the ceiling is attached utilizing metal channels
    • Annex: The gypsum board (or equivalent material) used as the firestopping will compartment the concealed space and restrict the ability for fire to spread beyond 160 ft3 (4.5 m3) zones covering multiple joist channels.
• 2025:
  • (5) Concealed spaces where rigid materials are used and the exposed surfaces comply with one of the following in the form in which they are installed in the space:
    • (a) The surface materials have a flame spread index of 25 or less and the materials have demonstrated that the flame front does not progress more than 10.5 ft (3.2 m) beyond the centerline of the burners at any time during the 30-minute test period, when tested in accordance with ASTM E84, Standard Test Method for Surface Burning Characteristics of Building Materials, or UL 723, Test for Surface Burning Characteristics of Building Materials, extended for an additional 20 minutes in the form in which they are installed in the space.
  • (8) Vertical pipe chases under 10 ft2 (0.9 m2), provided that in multifloor buildings the chases are constructed with blocking at each floor and pipe penetrations at each floor are properly sealed, and where such pipe chases contain no sources of ignition, and piping is noncombustible
  • (10) Light or ordinary hazard occupancies where noncombustible or limited-combustible ceilings are attached to the bottom of composite wood joists either directly or on to metal channels not exceeding 1 in. (25 mm) in depth, provided the adjacent joist channels are constructed with blocking so that volumes not exceeding 160 ft3 (4.5 m3) using materials equivalent to 1⁄2 in. (13 mm) gypsum board, and at least 31⁄2 in. (90 mm) of batt insulation is installed at the bottom of the joist channels when the ceiling is attached utilizing metal channels
    • Annex: The gypsum board (or equivalent material) used as the blocking material will compartment the concealed space and restrict the ability for fire to spread beyond 160 ft3 (4.5 m3) zones covering multiple joist channels.

19.2.3.2 Density/Area Method.

19.2.3.2.1 Water Supply.

• 19.2.3.2.1.1
  • 2022: “The water supply requirement for sprinklers only shall be calculated from Table 19.2.3.1.1 for new systems and from the density/area curves of Figure 19.2.3.1.1 for the evaluation or modification of existing systems, or from Chapter 27where density/area criteria are specified for special occupancy hazards.”
  • 2025: “The water supply requirement for sprinklers only shall be calculated from Table 19.2.3.1.1 or from Chapter 27 where density/area criteria are specified for special occupancy hazards.”
• 19.2.3.2.1.2 (Deleted in 2025)
  • When using Figure 19.2.3.1.1, the calculations shall satisfy any single point on the appropriate density/area curve.
• 19.2.3.2.1.3 (Deleted in 2025)
  • When using Figure 19.2.3.1.1, it shall not be necessary to meet all points on the selected curves.

19.2.3.2.4 Sloped Ceilings.

• 2022:
  • The system area of operation shall be increased by 30 percent without revising the density when the following types of sprinklers are used on sloped ceilings with a pitch exceeding 1 in 6 (a rise of 2 units in a run of 12 units, a roof slope of 16.7 percent) in nonstorage applications:
    1. Spray sprinklers, including extended coverage sprinklers listed in accordance with 11.2.1(4), and quick-response sprinklers
    2. CMSA sprinklers
• 2025:
  • Where spray sprinklers, including extended-coverage and quick-response sprinklers, are installed under a ceiling/roof deck with a slope that exceeds 2 in 12, one of the following requirements shall be implemented:
    1. A horizontal false ceiling capable of withstanding an uplift force of 3 lb/ft2 (14.6 kg/m2) is installed below the sloped ceiling and supplemented with ceiling sprinklers.30% increase (unobstructed)
    2. The design area for the ceiling sprinkler system is increased by 30 percent for unobstructed construction.Mandatory sprinkler-in-channel layouts
    3. Where the ceiling slope does not exceed 4 in 12, apply the sprinkler system criteria specified in Chapter 19 when all of the following conditions are met:
       1. Purlins or beams supporting the roof deck run across the roof slope.
       2. Purlins or beams do not exceed 18 in. (450 mm) deep.
       3. Purlins or beams do not exceed 5 ft (1.5.m) on center.
       4. Bays created by the solid structural members are not more than 40 ft (12 m) on center.
       5. Purlin or beam channels are provided with blocking above each solid structural member.
    4. For obstructed construction where the ceiling slope does not exceed 4 in 12, install sprinklers in every channel.
    5. For obstructed construction that does not meet (3) or (4), the design area for the ceiling sprinkler system is increased by 30 percent.

19.2.3.2.5 Sprinklers for Ceiling Heights Over 30 ft (9.1 m). (New in 2025)

“Where sprinklers are installed in areas with ceiling heights greater than 30 ft (9.1 m) above the finished floor, the requirements of Section 19.2 shall apply except as modified by 19.2.3.2.5 and Table 19.2.3.2.5.”

   

19.2.3.2.5.1 General Sprinkler Characteristics for Ceiling Heights over 30 ft (9.1 m).

(A)

• Sidewall sprinklers shall not be permitted for use in Ordinary Hazard Group 1 and higher occupancy hazards where the ceiling height is greater than 30 ft (9.1 m). [See 10.3.2(3).]
• Annex: The results of Test Nos. 1 and 2 listed in Table C.‍27 demonstrate that standard-response K-5.6 (K-80) and K-8.0 (K-115) sprinklers can provide fire control for a simulated Ordinary Hazard Group 1 storage array under a 58 ft (17.7 m) high ceiling using a 0.15 gpm/ft2 (6.1 mm/min) density. However, the number of sprinklers that operated resulted in a design area larger than that specified in Table 19.2.3.1.1 coupled with significant sprinkler skipping for both tests. As a result, the design areas in Table 19.2.3.1.1 are being increased, while maintaining the same design density, to account for the test results.

(B)

• Sprinklers having a nominal K-factor less than K-11.2 (K-160) shall not be permitted for use in Ordinary Hazard Group 2 and higher occupancy hazards where the ceiling height is greater than 30 ft (9.1 m). (See 9.4.5.)
• Annex: The results of a test reported in the 2014 Suppression Detection conference proceedings (available from the NFPA Library) demonstrated that standard-response K-8.0 (K-115) sprinklers can provide fire control for a simulated Ordinary Hazard Group 2 storage array under a 40 ft (12.2 m) high ceiling using a 0.37 gpm/ft2 (15 mm/min) density. However, with 12 sprinklers operating during this test, it demonstrated that a density of 0.37 gpm/ft2 (15 mm/min) is more applicable than the density of 0.20 gpm/ft2 (8.1 mm/min) that is provided in Table 19.2.3.1.1 and therefore has been given as the design density for this ceiling height. In addition, the results from Test Nos. 6 and 7 in Table C.‍27 along with a test reported in the 2014 Suppression Detection conference proceedings (available from the NFPA Library) suggest that the use of a K-11.2 (K-160) sprinkler will provide better fire control, as suggested by the requirements given in 21.1.4, even though this is not a storage occupancy.

(C)

• Extended-coverage pendent sprinklers having a nominal K-factor of K-22.4 (K-320) or less shall not be permitted for use in Ordinary Hazard Group 2 and higher occupancy hazards where the ceiling height is greater than 30 ft (9.1 m). (See 11.2.1.1.)
• Annex: The results of Test Nos. 6 and 7 listed in Table C.‍27 demonstrated that quick-response K-11.2 (K-160) sprinklers can provide fire control for a simulated Ordinary Hazard Group 2 storage array under a 60 ft (18.3 m) high ceiling using a 0.45 gpm/ft2 (18.3 mm/min) density. However, with 13 and 16 sprinklers operating during these two tests, it demonstrated that a density of 0.45 gpm/ft2 (18.3 mm/min) is more applicable than the density of 0.20 gpm/ft2 (8.1 mm/min) that is provided in Table 19.2.3.1.1 coupled with a design area greater than the 1500 ft2 (140 m2) given in Table 19.2.3.1.1. As a result, the original design density of 0.20 gpm/ft2 (8.1 mm/min) has been increased to 0.45 gpm/ft2 (18.3 mm/min), and the design area of 1500 ft2 (140 m2) has been increased by 30 percent. The 30 percent increase to the design area, however, was not applied to the K-25.2 (K-360) extended-coverage sprinkler due to the very positive results (only one sprinkler operated) obtained with it during Test 8 listed in Table C.‍27.

(D)

• Standard-response standard-coverage sprinklers shall not be permitted for use in Ordinary Hazard Group 2 occupancies where the ceiling height is greater than 30 ft (9.1 m). (See 10.2.5.)
• Annex: The large-scale fire testing applicable to the requirements of this section demonstrated that for standard-coverage sprinklers, the use of quick-response sprinklers provided an acceptable level of fire control for simulated Ordinary Hazard Group 2 occupancy hazards. As a result, quick-response standard-coverage sprinklers with K-factors of K-11.2 (K-160) or greater are required for the protection of Ordinary Hazard Group 2 occupancy hazards where the ceiling height exceeds 30 ft (9.1 m).

19.2.3.2.5.2 Sprinkler Density/Areas for Ceiling Heights Over 30 ft (9.1 m).

(A)

• For Ordinary Hazard Group 1 occupancies where the ceiling height is greater than 30 ft (9.1 m), the design areas obtained from Table 19.2.3.1.1 shall be increased by 30 percent.
• Annex: The results of Test Nos. 1 and 2 listed in Table C.‍27 demonstrate that standard-response K-5.6 (K-80) and K-8.0 (K-115) sprinklers can provide fire control for a simulated Ordinary Hazard Group 1 storage array under a 58 ft (17.7 m) high ceiling using a 0.15 gpm/ft2 (6.1 mm/min) density. However, the number of sprinklers that operated resulted in a design area larger than that specified in Table 19.2.3.1.1 coupled with significant sprinkler skipping for both tests. As a result, the design areas in Table 19.2.3.1.1 are being increased, while maintaining the same design density, to account for the test results.

(B)

• For Ordinary Hazard Group 2 occupancies where the ceiling height is greater than 30 ft (9.1 m) but does not exceed 40 ft (12.2 m), the ceiling sprinkler system shall use a minimum density of 0.37 gpm/ft2 (15.1 mm/min) in combination with the design area obtained from Table 19.2.3.1.1.
• Annex: The results of a test reported in the 2014 Suppression Detection conference proceedings (available from the NFPA Library) demonstrated that standard-response K-8.0 (K-115) sprinklers can provide fire control for a simulated Ordinary Hazard Group 2 storage array under a 40 ft (12.2 m) high ceiling using a 0.37 gpm/ft2 (15 mm/min) density. However, with 12 sprinklers operating during this test, it demonstrated that a density of 0.37 gpm/ft2 (15 mm/min) is more applicable than the density of 0.20 gpm/ft2 (8.1 mm/min) that is provided in Table 19.2.3.1.1 and therefore has been given as the design density for this ceiling height. In addition, the results from Test Nos. 6 and 7 in Table C.‍27 along with a test reported in the 2014 Suppression Detection conference proceedings (available from the NFPA Library) suggest that the use of a K-11.2 (K-160) sprinkler will provide better fire control, as suggested by the requirements given in 21.1.4, even though this is not a storage occupancy.

(C)

• For Ordinary Hazard Group 2 occupancies where the ceiling height is greater than 40 ft (12.2 m), the ceiling sprinkler system shall comply with the following:
• Use a minimum density of 0.45 gpm/ft2 (18.3 mm/min)
• Increase the design areas obtained from Table 19.2.3.1.1 by 30 percent
• Use the design areas from Table 19.2.3.1.1, without a 30 percent increase, where an extended-coverage sprinkler having a minimum nominal K-factor of K-25.2 (K-360) is used
• Annex: The results of Test Nos. 6 and 7 listed in Table C.‍27 demonstrated that quick-response K-11.2 (K-160) sprinklers can provide fire control for a simulated Ordinary Hazard Group 2 storage array under a 60 ft (18.3 m) high ceiling using a 0.45 gpm/ft2 (18.3 mm/min) density. However, with 13 and 16 sprinklers operating during these two tests, it demonstrated that a density of 0.45 gpm/ft2 (18.3 mm/min) is more applicable than the density of 0.20 gpm/ft2 (8.1 mm/min) that is provided in Table 19.2.3.1.1 coupled with a design area greater than the 1500 ft2 (140 m2) given in Table 19.2.3.1.1. As a result, the original design density of 0.20 gpm/ft2 (8.1 mm/min) has been increased to 0.45 gpm/ft2 (18.3 mm/min), and the design area of 1500 ft2 (140 m2) has been increased by 30 percent. The 30 percent increase to the design area, however, was not applied to the K-25.2 (K-360) extended-coverage sprinkler due to the very positive results (only one sprinkler operated) obtained with it during Test 8 listed in Table C.‍27.

(D)

• For Extra Hazard Groups 1 and 2 occupancies where the ceiling height is greater than 30 ft (9.1 m), the ceiling sprinkler system shall use a minimum density of 0.45 gpm/ft2 (18.3 mm/min) in combination with the design areas obtained from Table 19.2.3.1.1.
• Annex: The test data listed in Table C.‍27 does not include any tests representing simulated occupancy hazards for either Extra Hazard Group 1 or Extra Hazard Group 2. However, based on the results from the test data listed in Table C.‍27, the minimum design density requirements of 0.30 gpm/ft2 (12.2 mm/min) for Extra Hazard Group 1 and 0.40 gpm/ft2 (16.3 mm/min) for Extra Hazard Group 2 are both now less than the 0.45 gpm/ft2 (18.3 mm/min) design density required for Ordinary Hazard Group 2. Therefore, the minimum design density for both Extra Hazard Group 1 and Extra Hazard Group 2 has been increased to 0.45 gpm/ft2 (18.3 mm/min) while maintaining the same required design area.

19.2.3.2.7 Extra Hazard Occupancies.

• 19.2.3.2.7.1
  • For extra hazard occupancies with ceilings not exceeding 30 ft (9.1 m) in height, the system area of sprinkler operation shall be permitted to be reduced by 25 percent without revising the density, but not to less than 2000 ft2 (185 m2) where one of the following conditions occurs:
    1. High-temperature sprinklers are used.
    2. K-11.2 (160) or larger sprinklers are used.
• 19.2.3.2.7.2
  • The 25 percent reduction permitted by 19.2.3.2.7.1 shall only be permitted to be applied once.

19.3 Special Design Approaches

19.3.1 Residential Sprinklers

19.3.1.3

• 2022: “Unless the requirements of 19.3.1.4 are met, the minimum required discharge…”
• 2025: “The minimum required discharge…”
  • In 2022, 19.3.1.4 was an explicit exception allowing listed discharge criteria <0.1 gpm/ft² for modifications/additions to existing residential systems.

19.3.1.4 (Deleted in 2025)

For modifications or additions to existing systems equipped with residential sprinklers, the listed discharge criteria less than 0.1 gpm/ft2 (4.1 mm/min) shall be permitted to be used.

19.3.1.4.1 (Deleted in 2025)

Where replacing residential sprinklers manufactured prior to 2003 that are no longer available from the manufacturer and that are installed using a design density less than 0.05 gpm/ft2 (2.0 mm/min), a residential sprinkler with an equivalent K-factor (± 5 percent) shall be permitted to be used provided the currently listed coverage area for the replacement sprinkler is not exceeded.

19.5 Design Approaches for Supplemental Sprinklers (New in 2025)

When required to be included in the hydraulic calculations in accordance with 28.2.4.7.4.3, the design approach for supplemental sprinklers shall be permitted to be based on the hazard located directly below the obstruction.

Chapter 20 – General Requirements for Storage

20.1 General

Annex added in 2025:

2025 adds an entirely new A.20.1 annex section providing extensive guidance on what information should be documented when sprinklers are tested at a laboratory for determining discharge criteria. This is a substantive new addition covering 19 line items of test documentation requirements plus recommendations for proposing installation limits. This annex did not exist in 2022.

When sprinklers are being tested at a laboratory for the purposes of determining sprinkler discharge criteria for a specific hazard, the entity sponsoring the testing should request that the laboratory provide them with a report or test data that documents how the tests were conducted and what the results of the tests were, but not include proprietary product design information about the sprinkler. The following information should be included for each test in the report or data package:

1. Material(s) being used as the fuel for the fire.
2. Dimensional details of test commodity and storage arrangement.
3. Nominal height of the stored commodity above the floor.
4. Nominal clearance between the top of storage and the ceiling.
5. Sprinkler identification number (SIN).
6. K-factor of the sprinkler.
7. Temperature rating and response characteristics of the sprinkler.
8. Distance of the sprinkler deflector (or thermal element) below the ceiling.
9. Orientation of the sprinkler (upright, pendent, horizontal).
10. Obstructions to sprinklers (if any) including the branch line piping for upright sprinklers.
11. Water pressure at sprinkler or flow from sprinkler during test.
12. Sprinkler spacing.
13. Fire location with respect to upright and pendent sprinkler(s). Typical test locations might include the following (note that tests are not required in all locations):
    • Under one sprinkler
    • Between two sprinklers on the same branch line
    • Between four sprinklers
    • At a dry spot in the sprinkler’s spray pattern as identified in flow testing
14. Fire location with respect to sidewall sprinkler(s). Test locations that should be considered include the following (note that tests are not required in all locations):
    • At the most remote location from a single sprinkler
    • Centered between two sprinklers at the far point of the coverage area
    • Centered between four sprinklers when sprinklers are on opposite walls spraying into a room or space
    • Directly underneath and behind a single sprinkler
    • On the same wall as the sprinklers, centered between two sprinklers
    • At a dry spot in the sprinkler’s spray pattern as identified in flow testing
15. Fire test results. The following are examples of successful criteria:
    • The fire does not show evidence of sustained combustion at the far ends of the main test array.
    • The fuel is not completely consumed.
    • The fire does not show evidence of sustained combustion at the outer edges of the target arrays.
    • The average one-minute temperature of a simulated steel structural member installed near the ceiling above ignition does not exceed 1000°F (538°C), or the ceiling temperatures are controlled so that they are below a predetermined limit.
    • Sprinklers do not operate at the edge of the protection array.
16. Number of sprinklers that open during the test, where they were in relation to the fire, and what time they opened after ignition.
17. Gas temperatures above ignition and near each installed sprinkler.
18. Description of area or commodity damaged by fire.
19. Other test conditions or parameters or observations that would help support a decision or limitation on the use of the sprinkler based on this test program.

The entity sponsoring the tests is responsible for proposing appropriate limits to the installation requirements and hazards that their sprinkler can protect based on the parameters of the fire tests and the results of those tests. This recommendation needs to include the following:

1. The number of sprinklers that would be appropriate for the design area.
2. The minimum discharge (pressure or flow) necessary from each sprinkler.
3. The number of sprinklers that operated in the worst-case fire test with an appropriate safety factor applied (typically 1.5) to that number to account for variables not considered during the test program.
4. An appropriate minimum number of sprinklers can be applied, depending on the hazard being protected.

20.4 Commodity Classes

20.4.1 Class I

Table A.20.4.1 (Class I Examples)

• 2022 listed “Appliances; major; no appreciable plastic trim; cartoned” as Class I.
• 2025 corrects to “exposed”, aligning with Table A.20.4(b), which has always shown the exposed version as Class I and cartoned as Class II.

Table A.20.4.3 (Class III Examples)

• 2022 included “Fabric; synthetic (except rayon and nylon); up to 50/50 blend” and “Thread or yarn; synthetic (except rayon and nylon); up to 50/50 blend; wood or paper spools” as Class III examples.
• 2025 removes both, consistent with Table A.20.4(b) listing these as Group A Nonexpanded.

20.4.8.1 Group B / Free-Flowing Group A Plastics

• 2022: “Group B plastics and free-flowing Group A plastics shall be protected the same as Class IV commodities.”
• 2025: “Unless the requirements of 20.4.3 are met, Group B plastics or free-flowing Group A plastics shall be protected the same as Class IV commodities.”

20.4.12 Baled Cotton (2022 Renumbered 20.4.11.1).

20.4.13 Plastic Motor Vehicle Components (2022 Renumbered 20.7 & 20.5.4).

20.5 Equivalent Storage Arrangement

Section title changed:

• 2022: “Storage Arrangement”
• 2025: “Equivalent Storage Arrangement”

20.5.3.3 Aisles and 20.5.3.4 Flues with all subsections (Deleted)

20.5.4 Plastic Motor Vehicle Components (Deleted)

20.6 Aisle and Flue Space Requirements for Storage. (New Section in 2025)

New standalone Section 20.6

20.6.2.1.2 (2022 origin 20.5.3.4.1.2)

• 2022: “For Class I through IV and Group A plastic nominal 6 in. (150 mm) longitudinal flue spaces shall be provided in double-row racks for storage over 25 ft (7.6 m).”
• 2025: “For Class I through Class IV and Group A plastic commodities in double-row open racks, a nominal 6 in. (150 mm) longitudinal flue space shall be provided for storage over 25 ft (7.6 m).” Adds “in double-row open racks” and “commodities” for clarity.

20.6.2.1.3 (New in 2025)

• 2025 adds a new subsection explicitly stating that:
• “For Class I through Class IV and Group A plastic commodities in multiple-row open racks, longitudinal flue spaces shall not be required when all of the following are met:
  • Minimum nominal 6 in. (150 mm) wide transverse flue spaces are provided on maximum 5 ft (1.5 m) intervals.
  • The rack depth does not exceed 20 ft (6.1 m).
  • The minimum aisle width is 3.5 ft (1.1 m).”

20.7 Protection Criteria for Roll Paper Storage.

20.7 Plastic Motor Vehicle Components (2022 Deleted as Standalone Section):

20.9 Building Construction and Storage: Heights and Clearance.

20.9.1 Ceiling Slope

Section title changed:

• 2022: “Ceiling Slope”
• 2025: “Sloped Ceilings”

Scope expanded:

• 2022: Criteria apply to “Chapters 20 through 25.”
• 2025: Criteria apply to “Chapters 20 through 26.” Chapter 26 is now explicitly included.

20.9.1.1 Protection Options

• 2025 adds Annex A.20.9.1.1: “The intent is to have a structural member that prevents the passage of heat. The member can have holes for penetrations with reasonable clearance and penetration sealant is not expected.”
• 2022 had only 2 options for storage under ceilings exceeding 2 in 12: (1) where a specific section in Chapters 20–25 permits it, or (2) in-rack sprinklers per Section 25.6 with no storage above.
• 2025 expands to 6 options, based on FPRF research:
  • In-rack sprinklers per Section 25.7 with no storage above highest in-rack level.
  • Install a horizontal false ceiling capable of withstanding 3 lb/ft² uplift, with ceiling sprinklers below.
  • Protect per guidance in Chapters 20–26 that specifically permits slopes exceeding 2 in 12.
  • For obstructed construction with slope ≤ 4 in 12 using CMDA: install sprinklers in every channel.
  • For unobstructed construction with slope ≤ 4 in 12: increase design area by 50%.
  • For obstructed construction with slope ≤ 4 in 12: use standard criteria if purlins/beams run across the slope, are ≤ 18 in. deep, ≤ 5 ft on center, bays ≤ 40 ft on center, and channels are blocked above each solid structural member.

Storage Height

• 20.9.3.2 (New in 2025): “The storage height shall be measured from the floor level to the top of the commodity.”

20.9.4 Clearance to Ceiling

• 20.9.4.2 through 20.9.4.5 Relocated from Chapter 20 into Chapter 21 as 21.1.9 through 21.1.9.3.

20.9.5 Roof Vents and Draft Curtains

• A.20.9.5.1 expanded:
  • 2022: “Sprinkler protection criteria are based on the assumption that roof vents and draft curtains are not being used.”
  • 2025: “…and could be detrimental to the performance of the sprinkler system. If manual roof vents are provided, care should be taken to not open the manual roof vents before the fire has been controlled or suppressed.” Substantive operational guidance added.
• 20.9.5.1 rewritten:
  • 2022: “Manually operated roof vents or automatic roof vents with operating elements that have a higher temperature classification than the automatic sprinklers shall be permitted.”
  • 2025: “Automatic roof vents shall not be required in areas protected by automatic sprinkler systems.”

20.9.5.2 rewritten:

• 2022: “ESFR sprinklers shall not be used in buildings with automatic heat or smoke vents unless the vents use a high-temperature rated, standard-response operating mechanism.”
• 2025: “Where automatic roof vents are provided, the automatic roof vents shall have a higher temperature rating and a higher RTI than the automatic sprinklers.”

20.10 Unsprinklered Combustible Concealed Spaces

20.10.2 (4) rewritten:

• 2022: A single condition, flame spread index ≤ 25 and materials not propagating fire more than 10.5 ft when tested per ASTM E84 or UL 723 extended 20 minutes.
• 2025: Splits this into two alternatives (a) and (b):
  1. Same as 2022, but with updated wording (“flame front does not progress more than 10.5 ft beyond the centerline of the burners at any time during the 30-minute test period”).
  2. New alternative: Materials may instead comply with ASTM E2768, Standard Test Method for Extended Duration Surface Burning Characteristics (30 min Tunnel Test). This new standard is recognized as an equivalent compliance path.

20.10.2 (7) rewritten:

• 2022: Vertical pipe chases required to be “firestopped at each floor using materials equivalent to the floor construction.”
• 2025: Requires chases to be “constructed with blocking at each floor.” The firestopping language is replaced with the simpler “blocking” requirement — a meaningful change in the construction standard applied.

20.16 Discharge Considerations: General.

20.16.4 Design Approaches for Supplemental Sprinklers (New in 2025)

“When required to be included in the hydraulic calculations in accordance with 28.2.4.7.4.3, the design approach for supplemental sprinklers shall be permitted to be based on the hazard located directly below the obstruction utilizing the bottom plane of the obstruction as the ceiling level.”

20.17 Protection of Idle Pallets

20.17.1 Wood Pallets

• 20.17.1.4 (New in 2025): “Idle wood pallets shall be permitted to be stored in racks when protected in accordance with Section 25.7 using the criteria for exposed expanded plastic commodity hazard.”

20.17.3 Idle Pallets Stored on Racks, on Shelves, and Above Doors

• 20.17.3.4 (New in 2025): “Idle pallets shall be permitted to be stored in racks when protected in accordance with Section 25.7 using criteria for exposed nonexpanded plastic commodity hazard.”

20.19 Protection of Racks with Solid Shelves\

• 2022: Section 20.19 contained a full set of detailed normative requirements including 20.19.1 General, 20.19.2 Open Racks Combined with In-Rack Sprinklers, 20.19.3.1–20.19.3.5 (vertical spacing of in-rack sprinklers), and 20.19.4.1–20.19.4.3 (horizontal spacing of in-rack sprinklers) — 10+ normative subsections with detailed criteria.
• 2025: The section is drastically shortened and replaces all of this with just two subsections:
  • 20.19.1: “Racks containing solid shelves shall comply with Section 25.3.”
  • 20.19.2: “Solid shelving requirements shall not apply to a noncombustible product stored with noncombustible storage aids, including pallets, straps, containers, and shelving material.”

Chapter 21 – Protection of High-Piled Storage Using Control Mode Density Area (CMDA) Sprinklers

The 2025 edition has consistently eliminated the new/existing system distinction throughout Chapter 21. The old density/area design curves (for existing systems) have been removed from Sections 21.2, 21.4.1.2, 21.4.1.3, 21.4.1.4, and 21.4.1.7. Only the single-point density tables (introduced in 2022 for new systems) remain, now applying universally.

21.1 General

21.1.5 (Removed in 2025): “Unless the requirements of 21.1.6 are met, the requirements of Table 21.5.1.1 shall not apply to modifications to existing storage application systems, using sprinklers with K-factors of K-8.0 (115) or less.”

21.1.6 (Removed in 2025): “Where applying the requirements of Table 21.5.1.1 utilizing the design criteria of 0.6 gpm/ft2 per 2000 ft2 (24.5 mm/min per 185 m2) to existing storage applications, the requirements of 21.1.4 shall apply.”

21.1.8 Discharge Considerations (Renumbered from 2022 21.1.10)

• 21.1.8.2 (Removed in 2025, formerly 21.1.10.2): “The calculations shall satisfy any single point on appropriate density/area curves for the evaluation or modification of existing systems.”

21.1.9 (Renumbered, 2022 Origin 20.9.4.2). Table slightly modified and renumbered accordingly.

 

• 21.1.9.1 (Renumbered, 2022 Origin 20.9.4.3). Table slightly modified and renumbered accordingly.
   

• 21.1.9.2 (Renumbered, 2022 Origin 20.9.4.4). Table slightly modified and renumbered accordingly.
   

• 21.1.9.3 (Renumbered, 2022 Origin 20.9.4.5)

21.2 Control Mode Density/Area Sprinkler Protection Criteria for Palletized, Solid-Piled, Bin Box, Shelf, or Back-to-Back Shelf Storage of Class I Through Class IV Commodities.

21.2.2 Protection Criteria for Palletized, Solid-Piled, Bin Box, Shelf, or Back-to-Back Shelf Storage of Class I Through Class IV Commodities Stored Over 12 ft (3.7 m) in Height.

• “New vs. existing” system distinction removed.
• Table is identical
• 2022 had a two-tier structure:
  • 21.2.2.1 General with 21.2.2.1.1 (new systems use Table 21.2.2.2.1) and 21.2.2.1.2 (existing systems may use density/area curves).
  • 21.2.2.2 New System Criteria (21.2.2.2.1 table, 21.2.2.2.2 back-to-back shelf).
  • 21.2.2.3 Evaluation or Modification of Existing Systems (21.2.2.3.1 through 21.2.2.3.7, including Figures 21.2.2.3.1, 21.2.2.3.2, 21.2.2.3.3, and all associated commentary and ASK THE AHJ blocks).
• 2025 eliminates the new/existing distinction entirely and replaces it with:
  • 21.2.2.1 System Criteria: a single subsection with one table and one back-to-back shelf rule.
  • 21.2.2.1.1 Densities from Table 21.2.2.1.1 (same values as 2022’s Table 21.2.2.2.1, renumbered).
  • 21.2.2.1.2 Back-to-back shelf rule (same as 2022’s 21.2.2.2.2, renumbered).
• All 21.2.2.3 (existing system density/area curves) is removed from 2025, including Figures 21.2.2.3.1, 21.2.2.3.2, 21.2.2.3.3, and subsections 21.2.2.3.1 through 21.2.2.3.7. This is a significant simplification; the density/area curves for existing systems are no longer included in this section of the 2025 text.

21.4 Control Mode Density/Area Sprinkler Protection Criteria for Rack Storage of Class I Through Class IV Commodities.

21.4.1 Protection Criteria for Rack Storage of Class I Through Class IV Commodities Stored Over 12 ft (3.7 m) Up to and Including 25 ft (7.6 m) in Height.

21.4.1.1 General

New/existing system distinction removed:

• 2022 had two subsections: 21.4.1.1.1 (new systems use tables) and 21.4.1.1.2 (existing systems may use density/area curves).
• 2025 collapses to a single 21.4.1.1 with unified direction, eliminating the split. Same substance as the new system path only.

21.4.1.2 Single- and Double-Row Racks

New/existing system distinction removed (substantive):

• 2022 had two tiers: 21.4.1.2.1 (New System Criteria with Tables 21.4.1.2.1.1(a)–(e)) and 21.4.1.2.2 (Evaluation/Modification of Existing Systems with Figures 21.4.1.2.2.1(a)–(e) and Table 21.4.1.2.2.1).
  • 21.4.1.2.2 Evaluation or Modification of Existing Systems for Single- or Double-Row Rack Storage of Class I Through Class IV Commodities Stored Over 12 ft (3.7 m) Up to and Including 25 ft (7.6 m) in Height. (Deleted in 2025)
    • Figures 21.4.1.2.2.1(a) through (e) and Table 21.4.1.2.2.1 (which directed users to those figures based on configuration) are entirely absent from 2025.
• 2025 has only one tier. Tables are renumbered 21.4.1.2.1(a) – (e). All density values within the tables are identical to 2022’s new system tables.

21.4.1.3 Protection for Multiple-Row Racks — Rack Depth Up to and Including 16 ft (4.9 m), Aisles 8 ft (2.4 m) or Wider, Storage Height Over 12 ft (3.7 m) Up to and Including 25 ft (7.6 m). (Renumbered 2022’s 21.4.1.5 and 21.4.1.6)

• New/existing system distinction removed.
• 2022 had 21.4.1.3.1 (New System) with Tables 21.4.1.3.1.1(a) – (e) and 21.4.1.3.2 (Existing System) with Table 21.4.1.3.2.1.
• Deleted – Table 21.4.1.3.2.1 (directing existing system users to density/area curves with 1.25× density multiplier) is entirely absent from 2025.
• 2025 has only one tier. Tables are renumbered 21.4.1.3.1(a) – (e). All density values are identical to 2022’s new system tables.

21.4.1.4 Protection for Multiple-Row Racks — Rack Depth Over 16 ft (4.9 m) or Aisles Narrower Than 8 ft (2.4 m), Storage Height Over 12 ft (3.7 m) Up to and Including 25 ft (7.6 m). (Renumbered 2022’s 21.4.1.4 and 21.4.1.5)

• New/existing system distinction removed.
• 2022 had 21.4.1.4.1 (New System) and 21.4.1.5 (Existing System with Table 21.4.1.5.1).
• 2025 combines under 21.4.1.4 with the new system table only. All density values are identical.
• Deleted – Existing system table for multiple-row racks (deep/narrow aisle):
• 2022’s 21.4.1.5 and Table 21.4.1.5.1 (directing existing system users to density/area curves) are entirely absent from 2025.

21.4.1.5 Multiple-Row Racks – Storage Height Over 12 ft (3.7 m) Up to and Including 25 ft (7.6 m). (Renumbered 2022’s 21.4.1.6)

• Table 21.4.1.5.1 (Deleted)

21.4.1.7 Ceiling Sprinkler Density Adjustments restructured:

• 2022’s 21.4.1.7 had two subsections:
  • 21.4.1.7.1: For existing systems, adjust densities from design curves using Figure 21.4.1.7.1.
  • 21.4.1.7.2: Slave pallet 20% density increase.
• 2025’s 21.4.1.6 Ceiling Sprinkler Density Adjustments.
  • Retains only the slave pallet increase (as 21.4.1.6.1).
• 21.4.1.7.1 and Figure 21.4.1.7.1 (Deleted in 2025)
  • The existing system density adjustment curve (Figure 21.4.1.7.1 — Evaluation or Modification of Existing System’s Ceiling Sprinkler Density vs. Storage Height) and its normative text are entirely absent from 2025

Chapter 22 – CMSA Requirements for Storage Applications

• Chapter 22’s 2022 and 2025 versions of the NFPA 13 code are identical.

Chapter 23 – ESFR Requirements for Storage Applications

23.2 ESFR Design Criteria

• 23.2.3 (New in 2025): “Where ESFR sprinklers are spaced less than the minimum distances permitted and nonstructural baffles are installed in accordance with 14.2.8.4.2(1) to compensate, the design area shall cover a minimum of 768 ft2 (71 m2).”

23.3 ESFR Sprinklers for Palletized, Solid-Piled, or Rack Storage of Class I Through Class IV and Group A Plastic Commodities.

Table 23.3.1

• Table format changed: 2025 adds an explicit maximum storage height column alongside maximum ceiling/roof height.
• Application is clearer: each ESFR option is now tied to a defined ceiling-height/storage-height c ombination.
• Class I–IV and cartoned nonexpanded Group A plastics: table presentation was reorganized so the allowable storage height is now explicitly shown for each ceiling height.
• Cartoned expanded Group A plastics: 2025 adds major new ESFR ceiling-only options, especially with K-22.4 and K-25.2 sprinklers, and extends protection to higher ceiling/storage combinations than were shown in 2022.
• Exposed nonexpanded Group A plastics: 2025 also adds major new ESFR ceiling-only options, again especially with K-22.4 and K-25.2 sprinklers, including higher ceiling/storage combinations.
• Exposed expanded Group A plastics: 2025 substantially reorganizes and clarifies the available options, explicitly separating the lower-pressure barrier-based options from the higher-pressure closed-array options.
• Important cross-reference change: the 2022 table note referring to Section 27.4 was changed in 2025 to Section 23.4, indicating that the exposed expanded Group A plastic barrier criteria are now more directly integrated into Chapter 23.
• New notes in 2025: the table now better distinguishes between options that are directly test-based and options derived from higher-hazard testing logic.

Chapter 24 – Alternative Sprinkler System Designs for Chapters 20 Through 25

24.1 General

• 2025:
  • 24.1 Annex adds: “Nothing in this chapter is intended to limit the development and use of equivalency or new technology applications under the provisions of Section 1.5 or Section 1.7.” Not present in 2022. Clarifies that Chapter 24 does not restrict equivalency pathways.

24.2 Sprinkler Design Criteria for Palletized and Solid-Piled, Storage of Class I Through Class IV and Plastic Commodities.

• Table 24.2.1 now adds footnote: “A minimum clearance of 5 ft (1.5 m) shall be provided from sprinkler deflector to the top of storage.”

24.3 Sprinkler Protection Criteria for Open-Frame Rack Storage of Class I Through Class IV and Plastic Commodities.

24.3.1:

• Table 24.3.1 adds the same footnote: “A minimum clearance of 5 ft (1.5 m) shall be provided from sprinkler deflector to the top of storage.”

24.3.2:

• 2022:
  • There were two separate tables:
    • Table 24.3.2(a) for K-25.2 upright
    • Table 24.3.2(b) for K-25.2 pendent
• 2025:
  • Those were consolidated into a single Table 24.3.2.

Table 24.3.3 new footnote:

• 2025 adds to Table 24.3.3: “For the 12-sprinkler design incorporate a 500 gpm (1900 L/min) hose stream allowance and a 90-minute duration.” This specific hose stream and duration requirement for the 12-sprinkler dry system design (40 ft storage / 45 ft ceiling) was not present in 2022 and is a substantive addition.

Chapter 25 – Protection of Rack Storage Using In-Rack Sprinklers

25.1 General Requirements for Ceiling and In-Rack Sprinklers Protecting Rack Storage.

25.1.1 Scope

25.1.1.1

• 2025 Annex adds after the 8-item checklist: “Fire testing of in-rack sprinkler protection schemes described in Chapter 25 have generally demonstrated improved fire protection compared to the ceiling-only sprinkler protection schemes described in Chapters 21 through 24. Lower ceiling temperatures and a reduced amount of smoke/combustion products developed during the fire control or suppression process has typically been observed during fire testing of these in-rack sprinkler systems. A reduction in the amount of smoke/combustion product generation provides greater visibility for the fire service while achieving final extinguishment.”

25.1.2 Chapter Organization

2022:

• 25.1 contains general requirements for the entire chapter.
• 25.2 contains requirements for the protection of miscellaneous and low-piled rack storage using in-rack sprinklers.
• 25.3 contains requirements for in-rack sprinkler protection in combination with CMDA ceiling-level sprinklers.
• 25.4 contains requirements for in-rack sprinkler protection in combination with CMSA ceiling-level sprinklers.
• 25.5 contains requirements for in-rack sprinkler protection in combination with ESFR ceiling-level sprinklers.
• 25.6 contains requirements for in-rack sprinkler protection independent of ceiling-level sprinklers.
• 25.7 contains requirements for the evaluation or modification of existing protection for miscellaneous and low-piled rack storage using in-rack sprinklers. (Removed in 2025)
• 25.8 contains requirements for the evaluation or modification of existing protection for CMDA ceiling-level sprinkler rack storage protection of Class I through Class IV commodities over 12 ft (3.7 m) and up to and including 25 ft (7.6 m) using in-rack sprinklers. (Removed in 2025)

2025:

• 25.1 contains general requirements for the entire chapter.
• 25.2 contains requirements for the protection of miscellaneous and low-piled rack storage using in-rack sprinklers.
• 25.3 contains requirements for in-rack sprinkler protection with solid shelves.
• 25.4 contains requirements for in-rack sprinkler protection in combination with CMDA ceiling-level sprinklers.
• 25.5 contains requirements for in-rack sprinkler protection in combination with CMSA ceiling-level sprinklers.
• 25.6 contains requirements for in-rack sprinkler protection in combination with ESFR ceiling-level sprinklers.
• 25.7 contains requirements for in-rack sprinkler protection independent of ceiling-level sprinklers.

25.1.7 Horizontal Location of In-Rack Sprinklers.

25.1.7.7

• 2022: “Where rack storage of Class I through Class IV commodities is up to and including 25 ft (7.6 m), in-rack sprinklers shall be permitted to be installed horizontally without regard to rack uprights. (See Section C.‍17.)”
• 2025: “In-rack sprinklers shall be a minimum 3 in. (75 mm) radially from the side of rack uprights. (See Section C.‍17.)”

25.1.7.8 & 2022’s 25.1.7.9

• 2022’s 25.1.7.8: “Where rack storage is over 25 ft (7.6 m) in height, in-rack sprinklers shall be a minimum 3 in. (75 mm) radially from the side of rack uprights.”
• 2022’s 25.1.7.9: “Where rack storage is over 25 ft (7.6 m) in height and will be protected by face sprinklers, the face sprinklers shall be located within the rack a minimum 3 in. (75 mm) from rack uprights and no more than 18 in. (450 mm) from the aisle face of storage.”
• 2025’s 25.1.7.8: “Face sprinklers shall be located within the rack a minimum 3 in. (75 mm) from rack uprights and no more than 18 in. (450 mm) from the aisle face of storage.”

25.2 Protection of Miscellaneous and Low-Piled Rack Storage Using In-Rack Sprinklers.

25.2.1 Miscellaneous Rack Storage.

25.2.1.4 Ceiling Sprinkler Design in Combination with In-Rack Sprinklers for Miscellaneous Storage.

• 25.2.1.4.1 & 25.2.2.4.1 (Typo Corrected)
  • 2022: “0.20 gpm/ft2 (0.8.2 mm/min)”
  • 2025: “0.20 gpm/ft2 (8.2 mm/min)”
• 25.2.1.4.3 (Wording Clarification)
  • 2022: “The sprinkler system criteria specified in this chapter for miscellaneous storage shall not be limited to a ceiling slope of 2 in 12 (16.7 percent).”
  • 2025: “The sprinkler system criteria specified in this chapter for miscellaneous storage shall be permitted for both horizontal and sloped ceilings.”

25.2.2 Low-Piled Rack Storage.

25.2.2.4 Ceiling Sprinkler Design in Combination with In-Rack Sprinklers for Low-Piled Storage.

• 25.2.2.4.2
  • 2022: “The sprinkler system criteria specified in this chapter for low-piled storage shall not be limited to a ceiling slope of 2 in 12 (16.7 percent).”
  • 2025: “The sprinkler system criteria specified in this chapter for low-piled storage shall be permitted for both horizontal and sloped ceilings.”

25.3 Protection of Racks with Solid Shelves. (New in 2025)

All flow rates, pressures, shelf area thresholds, vertical spacing dimensions, horizontal spacing dimensions, and extension-beyond-shelf distances are identical to the 2022 source sections. No technical values were changed.

• General requirements + open rack combined with in-rack protection rules (2022 Origin 20.19.1 and 20.19.2)
• Vertical spacing – CMDA sprinklers, solid shelves between 20–64 ft² (2022 Origin 20.19.3.1)
• Vertical spacing – CMDA sprinklers, solid shelves > 64 ft² or shelf spacing > 6 ft (2022 Origin 20.19.3.2)
• Vertical spacing – CMSA sprinklers, in-rack sprinklers required at all tiers below highest solid shelf (2022 Origin 25.4.1.3.1)
• Vertical spacing – ESFR sprinklers, in-rack sprinklers required at all tiers below highest solid shelf (2022 Origin: 25.5.1.3.1)
• Partial solid shelf obstruction requirements (2022 Origin 20.19.3.5)
• Horizontal spacing – Class I–IV commodities (10 ft rule) (2022 Origin 20.19.4.1, also duplicated in 25.4.1.2.1 and 25.5.1.2.1)
• Horizontal spacing – Group A plastics (5 ft rule) (2022 Origin 20.19.4.2, also duplicated in 25.4.1.2.2 and 25.5.1.2.2)
• Extension of in-rack sprinklers beyond solid shelf edge (4 ft rule) (2022 Origin 20.19.4.3, also duplicated in 25.4.1.2.3 and 25.5.1.2.3)

25.4 In-Rack Sprinkler Protection in Combination with CMDA Ceiling-Level Sprinklers.

The changes in this section correspond to metrical conversion corrections.

TABLES 25.3.2.1.2.1(A)(a)–(A)(d) / 25.4.2.1.2.1(A)(a)–(A)(d)

• Area designation corrected:
  • 2022: “2000 ft² (186 m²)” in the column header for Tables (A)(a)–(A)(d).
  • 2025: “2000 ft² (185 m²)”.
• Minor metric rounding corrections in individual density values:
  • Several mm/min equivalents are slightly adjusted for rounding consistency. All gpm/ft² values are identical; only the parenthetical SI equivalents change in a handful of cells. Examples found on the values corresponding to “Ceiling Sprinkler System Design [gpm/ft2/2000 ft2 (mm/min/185 m2)]”, below both “High-Temperature-Rated Sprinklers” and “Ordinary- or Intermediate-Temperature-Rated Sprinklers”:
    • 0.17 (7.0), 0.17 (6.9)
    • 0.18 (7.4), 0.18 (7.3)
    • 0.22 (8.8), 0.22 (9.0)
    • 0.23 (9.3), 0.23 (9.4)

25.5 In-Rack Sprinkler Protection in Combination with CMSA Ceiling-Level Sprinklers.

25.4.1 Solid Shelves subsection (2022 Deleted):

• 2022 had a dedicated 25.4.1 with subsections 25.4.1.1 through 25.4.1.3.2 covering solid shelf requirements specific to CMSA in-rack protection (general, horizontal spacing, vertical spacing including “install beneath all tiers under highest solid shelf”).
• 2025 eliminates this subsection entirely from Section 25.5 and relocated it to Section 25.3.

Section reorganized without 25.4.1: Former 25.4.2 (arrangements) becomes 25.5.1; former 25.4.3 (ceiling designs) becomes 25.5.2.

25.5.2.2 Open Wood Joist Construction with CMSA Ceiling-Level Sprinklers.

The term “blocking” replaced the term “Firestopping”: All references to “firestopping” in 25.4.3.2.1 and 25.4.3.2.2 replaced with “blocking” in 25.5.2.2.1 and 25.5.2.2.2.

25.6 In-Rack Sprinkler Protection in Combination with ESFR Ceiling-Level Sprinklers.

• 2022 25.5.1 Solid Shelves (Deleted): 25.5.1.1 through 25.5.1.3.2 covering ESFR-specific solid shelf requirements is deleted. This content is now in Section 25.3.

25.6.3.3 Design Area Rule Simplified

• 2022: “The design area…shall consist of the most hydraulically demanding area of 12 sprinklers, consisting of four sprinklers on each of three branch lines.” Complete rule stated with historical commentary about the shift from 14 to 12 sprinklers.
• 2025: “The design area…shall comply with Section 23.2.” Cross-reference only; historical commentary deleted.

25.7 In-Rack Sprinkler Protection Options Independent of Ceiling-Level Sprinklers.

• Table 25.7.3.1:
  • Text clarification in multiple table rows:
    • 2022: “Cartoned expanded Group A plastics (Also, Class I–IV and cartoned nonexpanded Group A plastics)” at 100 gpm
    • 2025: “Class I–IV, cartoned Group A plastics (both nonexpanded and expanded), and exposed nonexpanded Group A plastics” — adds exposed nonexpanded Group A plastics to the 100 gpm / 30 ft vertical option.
  • Table 25.7.3.1 Footnote “a” (Deleted): “For maximum rack depths of 16 ft (4.9 m) for Option 2 and Option 3.”
• 25.7.3.2.3 (New in 2025): “Where there is no storage above the highest level of in-rack sprinklers, the ceiling-level sprinkler system shall be in accordance with Chapter 19 and not consider the contents of the racking structure.”

25.7 Evaluation or Modification of Existing Protection for Miscellaneous and Low-Piled Rack Storage Using In-Rack Sprinklers. (Deleted in 2025)

• 25.7.1 Miscellaneous (design criteria, horizontal spacing, ceiling design per Figure 25.7.1.4.1, density/area modifiers, hose connections)
• 25.7.2 Low-piled (ceiling design Figure 25.7.2.4.1, solid shelf provisions referencing 20.19)
• Complete deletion consistent with 2025 policy of eliminating all existing-system-specific sections.

25.8 Evaluation or Modification of Existing CMDA Ceiling-Level Sprinkler Rack Storage Protection of Class I through Class IV Commodities Over 12 ft (3.7 m) and Up to and Including 25 ft (7.6 m) in Height Using In-Rack Sprinklers. (Deleted in 2025)

• 25.8.1 General (Table 25.8.1.1.2, design criteria, Figure 25.8.1.2.8)
• 25.8.2 Exposed nonencapsulated Class I–IV (arrangement figures, Table 25.8.2.2.1, density/area curves with Figures 25.8.2.2.1(a)–(d), density adjustment tables)
• 25.8.3 Encapsulated/cartoned Class I–IV (arrangement figures, Table 25.8.3.2.1 with density multipliers, Figures 25.8.3.2.1(a)–(g), Tables 25.8.3.2.2.4)
• Extensive commentary including “CLOSER LOOK” on density/area curves, “ASK THE SYSTEM DESIGNER” blocks, and References Cited.

Chapter 26 – Special Designs of Storage Protection

26.4 Special Design for Rack Storage of Class I Through Class IV Commodities and Group A Plastics Stored Up to and Including 20 ft (6.1 m) in Height

• 26.4.1.3 ESFR Slatted Shelf Protection had 8 conditions:
  • 2022 Item (3): “Longitudinal flue spaces shall not be required.”
  • 2025 Item (3): “Longitudinal flue spaces at least 6 in. (150 mm) wide shall be provided for double-row racks.”
• 2025 26.4.1.3 expands to 10 conditions by adding conditions 9 and 10:
  • Item (9): “There shall be no slatted shelf levels in the rack above 12 ft (3.7 m).”
  • Item (10): “Open rack shelving using wire mesh shall be permitted for shelf levels above 12 ft (3.7 m).”
  • These two items were already present in 26.4.1.2 (the CMDA slatted shelf section) as item (4), but were absent from the 2022 ESFR version (26.4.1.3).

26.6 Control Mode Density/Area Sprinkler Protection Criteria for Cartoned Records Storage with Catwalk Access

26.6.6 Sprinkler Criteria

 

Figure 26.6.6.4 has been updated and now gives an elevation view plus a plan view. In the past version it only showed the plan view.

26.6.6.4.1 Single-Row Racks

26.6.6.4.1.2

• 2022: “sprinklers…shall be staggered horizontally such that the sprinkler at first level is not less than 18 in. (450 mm) but not greater than 24 in. (600 mm) from the face of the rack on the catwalk side.”
  • “At the next level, the sprinkler in the transverse flue shall be located not less than 6 in. (150 mm) but not greater than 12 in. (300 mm) from the back face of the rack.”
  • “This staggering shall be repeated throughout all catwalk levels.”
• 2025: “sprinklers…shall be installed not less than 18 in. (450 mm) but not greater than 24 in. (600 mm) from the face of the rack on the catwalk side.” — Sub-items (A) and (B) deleted; the back-face positioning rule and the explicit staggering repetition requirement are removed. Only the catwalk-side dimension is retained.”

26.6.6.4.2 Double- and Multiple-Row Racks.

• 26.6.6.4.2.2 (New in 2025): “Where only one catwalk level has been installed, both the ‘X’ and ‘Δ’ in-rack sprinklers as shown in Figure 26.6.6.4 shall be installed.”

Chapter 27 – Special Occupancy Requirements

• The term “ignitible” is used in Chapter 27 to refer to flammable or combustible materials.

27.2 Ignitible (Flammable and Combustible) Liquids.

• Title change of 27.2.
  • 2022: 27.2 Flammable and Combustible Liquids.
  • 2025: 27.2 Ignitible (Flammable and Combustible) Liquids.

27.6 Dipping, Coating, and Printing Processes Using Ignitible (Flammable or Combustible) Liquids.

• 2025: Fire sprinkler systems for the protection of dipping, coating, and printing processes using ignitible (flammable or combustible) liquids shall be designed and installed in accordance with this standard and NFPA 34.

Chapter 28 – Plans and Calculations

28.1 Working Plans

28.1.3

• New item (4):
  • “Full height cross section or schematic diagram, including structural member information as required for clarity.”
  • This shifts all subsequent items by one number (2022’s items 4–23 become 2025’s items 5–24).
• New water source subitems (m) and (n) in 2025 item (14):
  • 2022: item (13) for water source information had subitems (a) through (l).
  • 2025: item (14) adds:
    • (m) “Size of city main in street and whether dead end or circulating; if dead end, direction and distance to nearest circulating main; and city main test results and system elevation relative to test hydrant.”
    • (n) “Private fire service main sizes, lengths, locations, weights, materials, point of connection to city main; the sizes, types, and locations of valves, valve indicators, regulators, meters, and valve pits; and the depth that the top of the pipe is laid below grade.”
• New sprinkler legend item (xi) in 2025 item (18)(b): “Sprinkler wrench model number(s).” Not required in 2022.
• New maintenance information subitem iii in 2025 item (24)(d): “Location of all low point drains”

28.2 Hydraulic Calculation Procedures

28.2.4.2.3.1 (New in 2025):

• 2025: “Where additional sprinklers are carried over to the next branch line, the flow from the sprinklers that create the hydraulically most demanding remote area within the dimension required by 28.2.4.2.1 shall be selected.”
• Annex: “For most tree and loop systems, the hydraulically most demanding sprinklers will be those closest to the cross main. For gridded systems, the hydraulically most remote sprinklers could end up being any of those along the adjacent branch line, grouped together within the 1.2 length.”

28.2.4.3 CMSA Sprinkler Method

• 28.2.4.3.1
  • 2022: “For CMSA sprinklers, the design area shall be a rectangular area having a dimension parallel to the branch lines at least 1.2 times the square root of the area protected by the number of sprinklers to be included in the design area. The design area protected by the number of sprinklers to be used by the 1.2 rule shall be based on the maximum allowable area per sprinkler.”
  • 2025: “For CMSA sprinklers, the design area shall be a rectangular area having a dimension parallel to the branch lines determined in accordance with 28.2.4.2 with the design area (A) being calculated by multiplying the required number of sprinklers by the actual floor area covered by those sprinklers.”
• 28.2.4.3.3
  • 2022: “In systems having branch lines with an insufficient number of sprinklers to fulfill the 1.2 requirement, the design area shall be extended to include sprinklers on adjacent branch lines supplied by the same cross main.”
  • 2025: “In systems having branch lines with an insufficient number of sprinklers to fulfill the dimension along the branch line requirement, the design area shall be extended to include sprinklers on adjacent branch lines supplied by the same cross main.”

28.2.4.4 ESFR Sprinkler Method

• 2022: “For ESFR sprinklers, the design area shall consist of the most hydraulically demanding area of 12 sprinklers, consisting of 4 sprinklers on each of three branch lines, unless other specific numbers of design sprinklers are required in other sections of this standard.”
• 2025: “For ESFR sprinklers, the design area shall be in accordance with the applicable sections in Chapters 23 and 25.”

28.2.4.4.1 (New in 2025):

• 2025: “Where the design area was increased to 18 sprinklers due to the slope of the ceiling or roof, the design area shall be five sprinklers on the most demanding three branch lines and the three most demanding sprinklers on the next most demanding branch line.”

28.2.4.7.3 and 28.2.4.7.4 – Obstruction Sprinklers Reorganized

• 28.2.4.7.4.1 (2022 Origin 28.2.4.7.3.1):
  • 2022: Sprinklers under the obstruction shall not be required to be included in the hydraulic calculation of the ceiling sprinklers.
  • 2025: Suplemental sprinklers under the…
• 28.2.4.7.4.2 (Renumbered 2022 28.2.4.7.3.2)

28.2.4.7.4.3 (New in 2025) with subitems (A) through (E):

2025 adds an entirely new subsection: “Where the requirements of 28.2.4.7.4.2 are not met, a level of supplemental sprinklers shall be calculated to verify pipe sizes.”

• Maximum of four adjacent sprinklers on a branch line.
  • If there is a single line of sprinklers installed under the obstruction, then four sprinklers on the same branch line should be included in the hydraulic calculations. If, however, there is more than one line of sprinklers installed under the obstruction, then the hydraulic calculations should account for two sprinklers on two lines.
• For density/area: area of coverage = footprint of obstruction only.
• For density/area: design criteria per Section 19.5.
• For CMSA and ESFR: discharge pressure per 20.16.4.
• Supplemental sprinkler level not required to be balanced with overhead system.

28.2.4.8.1

• Item (1) expanded to include flexible hose fittings:
  • 2022: “Pipe, fittings, and devices such as valves, meters, flow switches in pipes 2 in. (50 mm) or less in size, and strainers shall be included…”
  • 2025: “Pipe, fittings, flexible sprinkler hose fittings, and devices such as valves, meters, flow switches, and strainers shall be included…” — Adds flexible hose fittings explicitly; removes the 2 in. size qualifier from flow switches.
• Added item (12) – Flexible hose fitting losses:
  • 2025 inserts: “(12) Losses for flexible sprinkler hose fittings shall be based upon the number of bends referenced in the listing for the hose length.”
• Added item (15) – Vacuum pressure C value = 120:
  • 2025: “(15) In new systems, an increased C value of 120 shall be permitted where vacuum pressure is provided in accordance with Section 8.11.”
• Added item (16) – Vapor corrosion inhibitor C value = 120:
  • 2025: “(16) In new systems, an increased C value of 120 shall be permitted where a vapor corrosion inhibitor is provided in accordance with 8.2.11.”

28.2.4.12 Maximum Operating Pressure

• 2022: “For extra hazard occupancies, palletized, solid-piled, bin box, back-to-back shelf storage, shelf storage, or rack storage, the maximum operating pressure of any sprinkler shall be 175 psi (12 bar).”
• 2025: “For sprinklers in extra hazard occupancies or designed in accordance with Chapters 20 through 26, the maximum operating pressure of any sprinkler shall be 175 psi (12 bar).”

28.4 Hydraulic Calculation Forms and Reports

Section title updated:

• 2022: “28.4 Hydraulic Calculation Forms”
• 2025: “28.4 Hydraulic Calculation Forms and Reports”

Subsection titles changed:

28.4.1 Handwritten Hydraulic Calculation Forms (2022 – 28.4.1 General)

28.5 Pipe Schedules

28.5.1 General

28.5.1.2 Pipe Schedule Exclusions (substantive)

• 2022: Single sentence: “Sprinkler systems having sprinklers with K-factors other than 5.6 nominal, listed piping material other than that covered in Table 7.3.1.1, extra hazard Group 1 and Group 2 systems, and exposure protection systems shall be hydraulically calculated.”
• 2025: Converted to numbered list with added item: “(3) Those having listed fittings other than what is covered in Table 7.4.1”.

Chapter 29 – Systems Acceptance

29.1 Approval of Sprinkler Systems

Title change

• 2022: referenced “Sprinkler Systems and Private Fire Service Mains.”
• 2025: title is just “Approval of Sprinkler Systems.”

29.1.2 (New in 2025):

• 2025: “The approval of sprinkler systems shall be permitted to be witnessed remotely in accordance with NFPA 915.”

29.1.3 (New in 2025):

• 2025: “The requirements of 29.2.7 shall apply when acceptance tests are automated.”

29.2 Acceptance Requirements

29.2.1 Hydrostatic Tests

29.2.1.4 Fire Pump Test Pressure

• 2022: “Where a fire pump is used for a system, the test pressure shall be determined using the shutoff pressure of the pump.”
• 2025: “…the test pressure shall be determined using the shutoff pressure of the pump plus the maximum static pressure of the water supply adjusted for elevation.”
• 29.2.1.4.1:
  • 2022: “Where a fire pump uses a pressure limiting device or variable speed motor, the test pressure shall be calculated ignoring the settings of the pressure limiting device.”
  • 2025′: “Where a fire pump uses a pressure limiting device or variable speed motor, the test pressure shall be based on the set pressure of the main relief valve.”
• 29.2.1.4.2 (New in 2025): “Where a main relief valve is not provided, the pressure shall be calculated ignoring the settings of the pressure limiting device.” — This preserves the 2022 rule as a fallback when no main relief valve exists, while establishing the relief valve set pressure as the primary basis.

29.2.1.8 Fire Department Connection Piping

• 2022: “…Piping between the exterior fire department connection and the check valve in the fire department inlet pipe shall be hydrostatically tested in the same manner as the balance of the system. After repair or replacement work affecting the fire department connection, the piping between the exterior and the check valve in the fire department inlet pipe shall be isolated and hydrostatically tested at 150 psi (10 bar).”
• 2025: Only the first sentence retained: “Piping between the fire department connection and the check valve in the fire department inlet pipe shall be hydrostatically tested in the same manner as the balance of the system.”

29.2.1.13 Differential Valve Clapper:

• 2022: “When subject to hydrostatic test pressures, the clapper of a differential-type valve shall be held off its seat to prevent damaging the valve.”
• 2025: “…the clapper of a dry pipe valve shall be in the position as stated by the manufacturer’s published instructions to prevent damaging the valve.”

29.2.3.2 Dry Pipe and Double Interlock Preaction Systems.

29.2.3.2.4 Dry System Air Pressurization (New in 2025, Former 29.2.3.2.4 Deleted)

• 2022: “The results shall be recorded using the contractor’s material and test certificate for aboveground piping… and the general information sign…”
• 2025: “Systems shall be filled with air through the approved air supply until the required set pressure of the valve is met.” and inserts two completely new subsections:

29.2.3.2.4.1 (New in 2025):

• “The system shall reach the required set pressure within 30 minutes from the time the air supply is opened.”

29.2.3.2.4.2 (New in 2025):

• “Systems maintained at or below 5°F (-15°C) shall be permitted to reach the required set pressure within 60 minutes.”

29.2.3.6 Wet Pipe System Air Venting Valves (New in 2025)

• 2025 adds an entirely new operational test subsection:
  • 29.2.3.6.1: “Where manual valves are installed in accordance with Section 16.7 to meet the air venting requirements of 8.1.5, they shall be operated during filling of the system.”
  • 29.2.3.6.2: “Manual valves shall remain open until water reaches the valve and trapped air has escaped.”

29.2.8 Negative Pressure Systems (New in 2025)

• 2025 adds a new section:
  • 29.2.8.1: “Vacuum dry pipe systems shall meet all of the acceptance testing requirements for dry pipe systems.”
  • 29.2.8.2: “Vacuum preaction systems shall meet the acceptance testing requirements for preaction systems.”

29.6 General Information Sign

29.6.1.2 Sign Placement

• 2022: “Such signs shall be placed at each system control riser, antifreeze loop, and auxiliary system control valve.”
• 2025: “Such signs shall be placed at each system riser.” The specific requirements for antifreeze loops and auxiliary system control valves are removed, leaving only “system riser.”

29.6.2 General Information Sign Contents

• 2025 inserts item (2): “Edition of NFPA 13.”

Chapter 30 – Existing System Modifications

Title Change:

• 2022: “Existing System Modifications”
• 2025: “Existing System Modifications or Evaluation”

30.1 General

30.1.1

• 2022: “In addition to the applicable requirements of this standard, the requirements of Chapter 29 shall apply where modifications or additions are made to existing systems.”
• 2025: “…where modifications, evaluations, or additions are made to existing systems.”

30.1.4

• 2025 Added Annex 30.1.4: “It is not the intent of this section to require a full hydraulic analysis of the existing piping system. This requirement should only verify that the additional friction loss through the backflow prevention device is not detrimental to the original calculations when compared with the new flow test data.”

30.1.5 (New in 2025):

• “Where existing system modifications include added or relocated sprinklers, or flexible sprinkler hose fittings are retroactively installed on existing systems, a hydraulic analysis or revised hydraulic calculations using current water supply data to accommodate the additional friction loss shall be completed as a part of the installation.”

30.3 Sprinklers

30.3.8 (New in 2025):

• “Sprinklers having a K-factor exceeding K-5.6 (80) and having ½ in. (15 mm) National Pipe Thread (NPT) shall be permitted to be installed in existing sprinkler systems if listed for such use.”

30.4 Evaluation of Existing Systems. (AUT-SSD) (New in 2025)

Added Annex A30.4:

• “Fire protection systems are designed and installed based on a specific set of circumstances and building uses. For example, the volume of water needed for a sprinkler system to control a fire in the built environment is based upon the intended use of the facility known at the time the sprinkler system was designed and installed. Revisions to properties used for storage represent one of the most common scenarios that impact the ability of systems to provide adequate protection. Some of the most common changes include raising the storage height, changing the storage method arrangement such as adding racks, installing solid shelves in rack structures, or decreasing the aisle widths between racks. Changes in product packaging with the use of foam inserts, bubble wrap, or other plastics or encapsulated storage can significantly increase the fire hazard. Changing from wood pallets to plastic pallets, converting to the use of plastic bin boxes, or revising or adding material handling systems such as conveyors could severely impact the effectiveness of the fire protection systems. The following are some examples of when existing system evaluations should be conducted:
  1. Tenant changes or process changes
  2. Occupancy or storage changes
  3. Fire pump replacements
  4. Water supply changes
  5. Backflow preventers replaced or added
  6. Replacing missing hydraulic information signs with no existing records”

30.4.1 General (New in 2025):

• “Where changes in the occupancy, hazard, water supply, storage commodity, storage arrangement, building modification, or other condition that affects the installation criteria of the system are identified, the existing system shall be evaluated based on the current hazard and water supply.”

30.4.2 Evaluation (New in 2025):

• “Evaluation of existing systems shall be in accordance with one of the following methods:
  • As a new system in accordance with this edition of the standard
  • In accordance with the edition of NFPA 13 utilized in the design and installation of the system”
• Annex: “Evaluation of existing systems is in references to the adequacy of the pipe schedule hazard classification and design densities (in the case of CMDA systems), as well as the number of sprinklers and pressures calculated with ESFR and CMSA sprinklers or systems. The evaluation of existing systems is not limited to storage applications but encompasses all occupancies. This section provides users with two options for evaluation of existing systems. The first option would be to treat the system as new by applying and using the nonexisting requirements in the current edition. The second option is to apply the edition of NFPA 13 that the sprinkler system was originally designed under.”

30.5 Modification of Existing Systems:

• 2022: “30.5 Existing Systems Area/Density Curves” (single paragraph)
  • A single-paragraph pointing to existing system density/area curves in Chapters 19, 21, and 25 is removed.
• 2025: “30.5 Modification of Existing Systems” (new multi-subsection section)
  • 2025 Section 30.5 consolidates pipe schedule and hydraulic revamping content formerly in 30.4 and 30.6:

30.5.1 Revamping of Pipe Schedule Systems (New in 2025):

Table 30.5.1.1 Extra Hazard Pipe Schedule (New in 2025)

 

30.5.2 Revamping of Hydraulic Design Systems (2022 Origin 30.6.1 – 30.6.4).

30.5.2.2 Annex (New in 2025):

• “It is not the intent of this section to require a full hydraulic analysis of the existing piping system in addition to the new sprinkler layout.”

30.6 System Design

30.6.5: “For modifications to existing systems equipped with ESFR sprinklers where ESFR sprinklers are used for the protection of light or ordinary hazard occupancies, 30.6.5.1 through 30.6.5.3 shall be permitted.”

• 30.6.5.1: “In light hazard occupancies, the protection area limitations of ESFR sprinklers shall be permitted to meet the protection area requirements of Table 10.2.4.2.1(a).”
• 30.6.5.2: “In light and ordinary hazard occupancies, the sprinkler spacing of ESFR sprinklers shall be permitted to meet the sprinkler spacing requirements of 10.2.5.”
• 30.6.5.3: “In light and ordinary hazard occupancies, the obstruction to the sprinkler discharge pattern of ESFR sprinklers shall be permitted to meet the obstruction discharge requirements of 10.2.7.2.”

30.7 Testing

30.7.1

• 2022: “Modifications to existing piping systems shall require testing at system working pressure.”
• 2025: “Modifications to existing piping systems shall be isolated and hydrostatically tested in accordance with 29.2.1.”

30.7.1.1:

• 2022: “Where modification is made to an existing system affecting more than 20 sprinklers, the new portion shall be isolated and tested at not less than 200 psi (14 bar) for 2 hours.”
• 2025: “Where modifications affect 20 sprinklers or less, the new portion shall be hydrostatically tested at system working pressure.”

30.7.1.2:

• 2022: “Modifications that cannot be isolated, such as relocated drops, shall require testing at system working pressure.”
• 2025: “Regardless of the number of sprinklers affected, modifications that cannot be isolated shall be hydrostatically tested at system working pressure..”

30.7.1.3:

• “Modifications to deluge systems shall be permitted to be flow tested in lieu of hydrostatic testing, to verify all the following:
  • Water discharge patterns from all the open spray nozzles or sprinklers
  • Adequate coverage of wetting surfaces to be protected
  • Design pressure at the most remote nozzle or sprinkler
  • Design pressure at the deluge valve”

Chapter 31 – Marine Systems

Identical to 2022.

Chapter 32 – System Inspection, Testing, and Maintenance

Identical to 2022.