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Plumbing Repairs And Utilities

18. Installation Standards

Install water piping for alteration, addition, or repair projects according to the following requirements:

a. Allow for settlement or movement of building when installing piping.
b. Provide pressure-reducing equipment to eliminate dangerous excessive pressures in water system.
c. Install shock absorbers, air chambers, or other pressure-reducing apparatus to eliminate water hammer. Place adequate cushioning chambers ahead of quick-opening valves. An assembly of a tee, a length of pipe, and a pipe cap securely welded in place is an effective cushioning chamber and is easily installed.
d. Install hangers to support pipe at 10-foot or smaller intervals. Allow for expansion and contraction of water piping, particularly hot-water lines.
e. Keep potable- and nonpotable-water supply systems entirely independent of each other.
f. Do not repair or extend a water system with pipe that has been used in nonpotable-water lines unless it has been thoroughly cleaned and sterilized by a method meeting the medical olficer's approval.
g. Protect supply outlet or connection to a fixture or appliance from backflow by installing an approved air gap or backflow preventer between outlet control valve and fixture. (See sec. IV.)
h. If water pipes, fixtures, and appliances are subjected to extremely cold temperatures, protect them against freezing.

(1) Place underground water pipes below freezing level or insulate them.
(2) Do not install pipes in outside walls unless pipes are insulated against freezing. Insulate pipes in accordance with instructions in OCE Specification CE-35. (See app. I.)
(3) When a building is to be vacated in cold weather, drain water system thoroughly. Check carefully to see that water is drained from all low points in water pipes. See paragraph 67, TB ENG 66, for further information on this matter.
(4) Provide all outside water connections with a shut-off or drain below frost line.

i. Use building mains, branches, and fixture connections which are large enough to provide an ample supply of water to all plumbing fixtures. If water supply is inadequate, fixtures become foul, unsanitary, and dangerous to health. See appendix II for data on pipe sizes. See also National Bureau of Standards Report BMS 79 and Federal Specification WV-P-54ia. (See app. I.) Amount of water delivered at fixtures depends on —

(1) Available pressure in main.
(2) Friction loss due to number of turns or flow obstructions.
(3) Size and length of supply pipe.
(4) Number of fixtures to be operated at one time.

j. Install all water piping so system can be drained by gravity.

(1) Pitch horizontal piping toward entry point or other low point.
(2) Provide plugs at low points except where a valve is necessary to drain a branch or main.