MIL-HDBK-1005/7A
(3)
A screened vent, an altitude valve, and an
overflow.
(4)
A water level indicator and alarm.
(5)
A valve vault.
(6)
Heating equipment for freezing climates.
(7)
Sampling access points.
d)
Structural Design. For criteria on structural
design, use AWWA Standard D100 for steel elevated tanks.
e)
Location. Adequate clearance should be provided
between the exposed steel of elevated tank legs and buildings,
structures, or open storage of any flammable materials.
Otherwise, fireproofing of legs is required. Refer to NFPA
Standard No. 22, Water Tanks for Private Fire Protection, for
details.
8.3.2.5
Hydropneumatic Tanks . For design criteria, refer to
booster system in MIL-HDBK-1003 series.
8.4
Protection
8.4.1
Freezing. In areas where frost penetration exceeds 30
in. (see Figure 1) protect storage tanks against freezing.
8.4.1.1
External Insulation. Cover all exposed piping
(including risers to elevated storage tanks) with adequate
insulation.
8.4.1.2
Heating Equipment . Special considerations for heating
equipment in locations where freezing can occur are given below.
a)
Aboveground and Elevated Tanks and Standpipes.
In locations where freezing can occur, heat should be provided
in accordance with the provisions of NFPA Standard No. 22. The
method of heating should be selected on the basis of economy of
installation and operation for the particular location involved.
b)
Exposed Piping and Valves. Provide electric
heating elements inside a small enclosure covering these parts.
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