In cold climates, where the water turnover in the
tank is sufficient to make tank heating unnecessary,
the following rule will be used to govern the size
of the riser, provided the rule would make the riser
larger than required by the preceding table for warm
and temperate zones. Where the location shows the
following temperatures on the isothermal maps
contained in NFPA 22, Water Tanks for Private Fire
Protection, the riser size indicated will be used.
Minus 12.2 degrees to minus 28.9 degrees C.
1220 mm
(Plus 10 degrees to minus 20 degrees F. 4 ft. 0 in.
riser)
Minus 29 degrees to minus 34 degrees C... 1520 mm
(Minus 20 degrees to minus 30 degrees F. 5 ft. 0 in.
riser)
Minus 34.4 degrees C..................... 1830 mm
(Minus 30 degrees F. and below......... 6 ft. 0 in.
riser)
In northern areas, water tanks that serve fire
systems primarily and those where the daily
consumption is small will be provided with heating
facilities in accordance with NFPA 22. The size of
commensurate with the W (Btuh) input from makeup
water during periods of minimum consumption;
however, the heating facility will be capable of
maintaining the coldest water in the tank at a
minimum temperature of 6 degrees C (42 degrees F).
Frostproof casings will not be provided in lieu of
heat for large riser tanks.
The capacity of the tank will be based on
calculations according to TM 5-813-4 WATER SUPPLY,
WATER STORAGE and TI 814-03 WATER DISTRIBUTION.
Generally a balcony around the bottom of the tank
will not be provided. The elevation at the top of
the foundation will be not less than 200 mm (8
inches) above the finished grade.
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The elevated tank shall have a storage capacity of [_____] L gallons. The
high-water level of tank shall be at elevation [_____] with the top of
column foundations at elevation [_____]. The range between high and low
water levels shall be approximately [_____] m feet. The existing grade at
the tank site is approximately elevation [_____]. The top of straight side
sheets, where a cone-shaped roof is furnished, shall not be less than 150
mm 6 inches above the top of the overflow weir. The tank diameter shall be
not less than [_____] mm feet and the riser diameter not less than [_____]
mm feet. The tank shall [be of the style shown] [have an ellipsoidal
bottom, with vertical side sheets and a cone shaped top, or shall be of an
elliptical or oval design as approved. In the latter design, the lower
section of the roof may be used for water storage]. The tower supporting
the tank shall be constructed of structural shapes of the open type, or of
tubular sections, to permit inspection and painting. The tower shall be
thoroughly braced with horizontal struts and diagonal ties. The tower
SECTION 13209
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