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All sprinkler pipes and fittings shall be so installed that they can be completely drained. On wet pipe systems, sprinkler pipes may be installed level. In dry pipe systems and portions of pre-action systems subject to freezing, branch lines shall be pitched at least one- half inch per ten feet and mains shall be pitched at least one-quarter inch per ten feet.
Drain pipes for system risers and mains shall be not less in size than given in the following table:
Size of Riser or Main | Size of Drain |
Two inches or less | 3/4 inch |
Less than four inches but greater than 2 inches | 1 1/4 inches |
Four inches or greater | Two inches |
Where sectional or floor control valves are provided, they shall be provided with a drain sized as shown in the above table to drain that portion of the system controlled by the sectional valve.
Where installed underground, drains shall be galvanized with galvanized fittings or other corrosion resistant material. Where exposed to the weather they shall be fitted with hoods or elbows turned down to prevent stoppage with ice.
Drain pipes shall be so arranged as not to expose any portion of the sprinkler system to frost and shall be so connected that they will not overflow domestic or other piping. Direct connection shall not be made between sprinkler drains and sewers.
On wet systems all piping for sprinklers in excess of 20 which may be trapped, shall have a separate drain valve and drain connection; piping for 20 or less sprinklers shall be provided with non-ferrous drain plugs except the drop to an individual sprinkler head. On dry pipe systems, piping for sprinklers in excess of 20 which are trapped shall be equipped with a drain consisting of two one-inch valves separated by a 12-inch length of two-inch in diameter pipe. Where fewer than 20 sprinklers are trapped the drain may consist of a valve not smaller than one-half inch.
(Prior code § 91-25; Amend Coun. J. 10-30-96, p. 31216, § 1)
Hand hose to be used for fire protection only may be attached to sprinkler pipes. The pipe and valve supplying the hose shall be not less than one inch and not larger than one and one-half inch. The hose shall not be larger than one and one-half inch. The nozzle orifice shall not be larger than one-half inch except that an adjustable spray nozzle may be used. Hand hose shall not be connected to pipe less than two and one-half inches unless the system has been hydraulically designed to include the water discharged from the hose at the point where the hose is connected to the system. Hand hose shall not be connected to a dry system.
(Prior code § 91-26; Amend Coun. J. 10-30-96, p. 31216, § 1)
All piping shall be protected against corrosion. Sprinkler heads located in places where subject to corrosion shall be especially designed or protected against such corrosion.
Where pipe is used underground, the pipe shall be protected against corrosion.
(Prior code § 91-28; Amend Coun. J. 10-30-96, p. 31216, § 1)
A test pipe of not less than one inch diameter, with a smooth bore corrosion resistant outlet giving a flow equivalent to one sprinkler of a type having the smallest orifice installed in the system, shall be provided on wet sprinkler systems. This test pipe shall be connected to the end of the most remote branch line at the highest level of the system. There shall be a separate test pipe for each system. A test valve, which is not exposed to freezing, shall be provided to allow use of the connection.
A test pipe as provided above shall be installed in each dry sprinkler system. The test valve shall be equipped with a brass plug or a nipple and cap.
(Prior code § 91-29; Amend Coun. J. 10-30-96, p. 31216, § 1)
In high-rise buildings the test pipe for a sprinkler system may be placed at the water flow switch or the valve controlling the sprinklers for an individual floor or portion of a floor. The test connection shall be a listed sight test connection utilizing an orifice equivalent to a sprinkler of a type having the smallest orifice used in the system. The test connection shall terminate at a drain capable of accepting full flow of one sprinkler under system pressure.
(Added Coun. J. 10-30-96, p. 31216, § 1)
A dry pipe system shall be permitted only where heat is not adequate to prevent freezing of water in all or sections of a system. If the sprinklers in such unheated spaces are 25 percent or less of the total number of sprinklers required on a system having a total of 100 or more sprinklers, only such 25 percent or less shall be on the dry system and the remainder shall be on the wet system.
The dry pipe system shall be isolated from the water supplies (or from the wet portion of the system, if a combined wet and dry pipe system) by a dry pipe valve located at an accessible point as near as practicable to the dry system, adequately protected against mechanical injury and freezing.
(Prior code § 91-30; Amend Coun. J. 10-30-96, p. 31216, § 1)
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