Page
：
4 of 8
Document No.U087143
Date
：
Oct/18/2019
Hydraulic Design Criteria
The minimum required sprinkler flow rates for systems designed to NFPA 13D or 13R are given in TABLE A as a function of
temperature rating and the maximum allowable coverage area. The sprinkler flow rate is the minimum required discharge from
the most hydraulically demanding sprinkler from each of the total number of “design sprinklers” as specified in NFPA 13D or
13R.
For systems designed to NFPA 13, the number of designed sprinklers is to be the four most hydraulically demanding sprinklers.
The minimum required discharge from each of the four sprinklers is to be the greater of the following:
・
The flow rates given in TABLE A for NFPA 13D and 13R as a function of temperature rating and maximum allowable
coverage area.
・
A minimum discharge of 0.1GPM/sq.ft. [4.07LPM/sq.m] over the “design area” comprised of the four most hydraulically
demanding sprinklers for the actual coverage area being protected by the four sprinklers.
TABLE A. NFPA 13D & 13R WET PIPE HYDRAULIC DESIGN CRITERIA for Model SS4451
For systems with ceiling types smooth flat horizontal, or beamed, or sloped, in accordance with NFPA 13D, 13R or 13 as
applicable.
Ordinary
Temperature Rating
162°F
(72°C)
Intermediate
Temperature Rating
175°F
(79°C)
Intermediate
Temperature Rating
205°F
(96°C)
Maximum
Coverage
Area
(a)
Ft. × Ft.
(m × m)
Maximum
Spacing
Ft.
(m)
Flow
(b)
GPM
(LPM)
Pressure
(b)
PSI
(bar)
Flow
(b)
GPM
(LPM)
Pressure
(b)
PSI
(bar)
Flow
(b)
GPM
(LPM)
Pressure
(b)
PSI
(bar)
Deflector
to
Ceiling
Installation
Type
Minimum
Spacing
Ft.
(m)
12×12
(3.7×3.7)
12
(3.7)
13
(49.2)
7.0
(0.48)
13
(49.2)
7.0
(0.48)
13
(49.2)
7.0
(0.48)
14×14
(4.3×4.3)
14
(4.3)
13
(49.2)
7.0
(0.48)
13
(49.2)
7.0
(0.48)
13
(49.2)
7.0
(0.48)
16×16
(4.9×4.9)
16
(4.9)
13
(49.2)
7.0
(0.48)
―
―
13
(49.2)
7.0
(0.48)
18×18
(5.5×5.5)
18
(5.5)
17
(64.4)
12.0
(0.83)
17
(64.4)
12.0
(0.83)
17
(64.4)
12.0
(0.83)
20×20
(6.1×6.1)
20
(6.1)
20
(75.7)
16.7
(1.15)
20
(75.7)
16.7
(1.15)
20
(75.7)
16.7
(1.15)
Smooth
Ceilings
1-1/16 to 4
Inches.
Beamed
Ceilings
per NFPA
13D, 13R
or 13
Installed in
beam
1-1/16 to
1-9/16
inches
below
bottom of
beam.
Pendent
or
Recessed
Pendent
8
(2.4)
(a) For coverage area dimensions less than the above mentioned, it needs to use the minimum required flow for the
Next Higher Coverage Area listed.
(b) Requirement is based on minimum flow in GPM/LPM from each sprinkler. The associated residual pressures are
calculated using the nominal K-Factor. Refer to Hydraulic Design Criteria Section for details.
Sprinkler Spacing Criteria
The minimum spacing between sprinklers is 8 feet (2.4m). The maximum spacing between sprinklers cannot go beyond the
coverage area calculated by using the specific hydraulic factors. (Ref. TABLE A)
