Lay out standard spray upright or pendent sprinklers in a rectangular room: the number of sprinklers, spacing in each direction, area per sprinkler and distance from walls, checked against NFPA 13. Optionally get the flow and pressure at each sprinkler.
Standard spray upright and pendent sprinklers. Values are the maximum protection area per sprinkler and maximum distance between sprinklers.
| Hazard / system | Max area (ft²) | Max area (m²) | Max spacing (ft) | Max spacing (m) | Max to wall |
|---|---|---|---|---|---|
| Light hazard, hydraulically calculated (noncombustible or unobstructed construction) | 225 | 20.9 | 15 | 4.6 | 7.5 ft (2.29 m) |
| Light hazard, pipe schedule system | 200 | 18.6 | 15 | 4.6 | 7.5 ft (2.29 m) |
| Light hazard, combustible obstructed construction | 168 | 15.6 | 15 | 4.6 | 7.5 ft (2.29 m) |
| Ordinary hazard (Group 1 and 2) | 130 | 12.1 | 15 | 4.6 | 7.5 ft (2.29 m) |
| Extra hazard, hydraulically calculated (density ≥ 0.25 gpm/ft²) | 100 | 9.3 | 12 | 3.7 | 6 ft (1.83 m) |
| Extra hazard, pipe schedule or density < 0.25 gpm/ft² | 90 | 8.4 | 12 | 3.7 | 6 ft (1.83 m) |
| High-piled storage (density ≥ 0.25 gpm/ft²) | 100 | 9.3 | 12 | 3.7 | 6 ft (1.83 m) |
All hazards: minimum 6 ft (1.8 m) between sprinklers and at least 4 in (102 mm) from walls. Check the edition of NFPA 13 adopted locally and the sprinkler's listing.
Continue with the Sprinkler K-Factor Calculator, Sprinkler Density Calculator and Fire Hydraulic Calculator, then size the supply with Fire Pump Sizing and Fire Water Tank Sizing.
For standard spray upright and pendent sprinklers, 15 ft (4.6 m) for light and ordinary hazard and 12 ft (3.7 m) for extra hazard and high-piled storage, with the area per sprinkler also limited by hazard.
225 ft² (20.9 m²) for hydraulically calculated light hazard, 130 ft² (12.1 m²) for ordinary hazard and 100 ft² (9.3 m²) for hydraulically calculated extra hazard. Pipe schedule systems and some construction types have smaller limits.
No more than half the allowable spacing, for example 7.5 ft (2.3 m) where the spacing limit is 15 ft, and not less than 4 in (102 mm) from the wall.
6 ft (1.8 m) for standard spray sprinklers, to prevent one sprinkler wetting its neighbour and delaying its operation, unless baffles are installed.
Divide the room length and width by the maximum spacing and round up to get rows and columns, then check that the actual spacing in each direction multiplied together does not exceed the maximum area per sprinkler. Increase the rows if it does.
No. It sets the layout. The hydraulic calculation then checks that the water supply delivers the design density over the design area, starting from the most remote sprinkler.
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