TABLE 8. Required Fire Flow and Hydrant Spacing*
Average area served per hydrant,
Number of ft^2 (m^2 )t
Required fire flow, standard
Population gal/mm (L/s) hose streams Direct streams Engine streams
22,000 4,500(284) 18 55,000(5,110) 90,000(8,361)
28,000 5,000(315) 20 40,000(3,716) 85,000(7,897)
40,000 6,000(379) 24 40,000(3,716) 80,000(7,432)
60,000 7,000(442) 28 40,000(3,716) 70,000(6,503)
80,000 8,000(505) 32 40,000(3,716) 60,000(5,574)
100,000 9,000 (568) 36 40,000 (3,716) 55,000 (5,110)
125,000 10,000(631) 40 40,000(3,716) 48,000(4,459)
150,000 11,00 0 (694 ) 4 4 40,00 0 (3,716) 43,00 0 (3,995)
200,000 12,000(757 ) 4 8 40,000(3,716 ) 40,000(3,716 )*National Board of Fire Underwriters,
tHigh-value districts.This means that 36 single-outlet or 18 dual-outlet hydrants are required. More, of course,
could be used if better protection were desired in the area. Note that the required fire flow
listed in Table 8 agrees closely with that computed in step 2 above.
Related Calculations. Use this general method for any water-supply system,
municipal or industrial. Note, however, that the required fire-protection quantities vary
from one type of municipal area to another and among different industrial exposures. Re-
fer to NFPA Handbook of Fire Protection, available from NFPA, 60 Batterymarch Street,
Boston, Massachusetts 02110, for specific fire-protection requirements for a variety of in-
dustries. In choosing a water-supply system, the wise designer looks ahead for at least 10
years when the water demand will usually exceed the present demand. Hence, the system
may be designed so it is oversized for the present population but just adequate for the fu-
ture population. The American Society for Testing and Materials (ASTM) publishes com-
prehensive data giving the usual water requirements for a variety of industries. Table 9
shows a few typical water needs for selected industries.
TABLE 9. Selected Industrial Water and Steam Requirements*
Air conditioning
Aluminum
Cement, portland
Coal, by-product coke
Rubber (automotive tire)
Electricity
Water
6000 to 15,000 gal (22,700 to
57,000 L) per person per
season
1,920,000 gal/ton (8.0 ML/t)
750 gal/ton cement (3129 L/t)
1430 to 2800 gal/ton coke
(5967 to 11, 683 L/t)80 gal/kW (302 L/kW) of
electricitySteam570 to 860 Ib/ton (382 to
427 kg/t)
120 Ib (54 kg) per tire*Courtesy of American Society for Testing and Materials.