MIL-HDBK-1005/7A
5.4.7.1
Water Seal. An independent water seal supply, not
connected to the potable water system or a potable water supply
protected by an air gap or backflow preventer, should be used
where the water quality or pump characteristics prevent a
self -sealing system as follows:
a)
When the suction lift exceeds 15 ft.
b)
When the discharge pressure is less than 23 ft.
c)
When the pump handles hot water.
d)
When the water is muddy, sandy, or gritty.
5.4.7.2
Stuffing Box Water Cooling. Cooling water should be
applied to the stuffing box jackets where pumps operate at a
high stuffing box pressure.
5.4.8
Surge Prevention. Surge or water hammer, produced by
a sudden change of flow in the pumping system, should be
carefully studied. For large, high pressure systems, the help
of a qualified expert is recommended; and his recommendation
should be incorporated into the design.
5.4.8.1
Surges are handled by one or more
of the following methods:
a) Moderating the valve closure time by either a
manual or automatic valve controller;
b)
A surge tank with a free water surface;
c)
An air chamber on the discharge line;
d)
A surge suppressor;
e)
A surge relief valve;
f)
A vacuum relief valve.
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