Fire Protection by Robert C. Till & J. Walter Coon

Author:Robert C. Till & J. Walter Coon
Language: eng
Format: epub
ISBN: 9783319908441
Publisher: Springer International Publishing

Main Control Valve

The main control valve is installed in the main water supply pipe to the sprinkler system, and controls all of the water to the sprinkler system. The control valve may be installed inside the building where the underground supply pipe enters the building, or it may be installed outside the building in the underground supply pipe. Inside or outside, all sprinkler systems, and in fact all fire protection control valves, are required to have one feature-visual indication of an open or shut position. This section will consider only the inside, or above ground, control valve.

The terms inside or outside control valves refer to valves installed in the underground pipe outside the building, as opposed to valves installed in the steel pipe of the sprinkler system above ground, and inside the building. A commonly used inside control valve for sprinkler systems is the Outside Screw & Yoke (OS&Y) valve.

This meets the requirement for all fire protection valves controlling water supplies; namely, a visual inspection will tell at a glance whether the valve is open or closed. As a result, all valves controlling water supplies must be indicating type valves, which means they must visually indicate whether they are open or shut.

There are several indicating type control valves on the market for use on fire protection systems. Except when the use of an OS&Y valve is required by NFPA or the insurance carrier, butterfly control valves may be considered to save space.

The control valve on a sprinkler system serves several basic functions. This is necessary in order to shut off the water supply to the system so that the system can be repaired, altered, or increased in size.

When the sprinkler system has suffered physical damage, and is discharging water through a broken pipe, fitting, or sprinkler head, the supply of water to the entire system can be stopped by closing the main control valve.

When the sprinkler system has performed within the efficiency of the design parameters and extinguished a fire, the water damage can be kept to a minimum by closing the main control valve and stopping the water supply to the heads that have been opened by the fire. At this point, it would be inexcusable not to mention the tragic record of major fire losses that have resulted from this misuse of the main control valve. A fire that produces enough heat to operate a sprinkler head cannot be safely declared officially extinguished by the average layman. All too often in their haste to avoid water damage, a main control valve will be prematurely closed because the fire appeared to be out. Control valves are not always conveniently located within eyesight of the fire. By the time the individual who has been dispatched to the basement where the valve is located returns to the third floor where the fire has occurred, he finds that the fire has re-ignited and is using the time for his return trip to reopen the valve to feed itself, uninterrupted by the sprinkler discharge.

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