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Chapter 8 Fire Protection Systems | Up
Utilitiesman (Advanced) - Manual for electric, plumbing, water and other utilities | Next
Figure 8-2. Alarm check valve (section) |
Dry Pipe System
In a dry pipe system, the pipes normally
contain either air or nitrogen under pressure. Dry
pipe systems are used in areas where the water in
the pipes is subject to freezing.
A dry pipe valve acts as a control between the
water supply and the air under pressure in the
piping network. The dry pipe valve must be in a
heated enclosure because pressurized water is at
the underside of the valve. A small amount of
water, called priming water, is also inside the dry
pipe valve itself to ensure a tight seal of the
clapper and to keep the rubber gaskets pliable. The
valve is usually made so that a moderate air
pressure holds back a much greater water
pressure. There are several types of dry pipe
valves.
87.349
Figure 8-1.—Alarm check valve.
8-2
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