(A) The owner or occupant of every premises receiving water supply shall apply and maintain suitable means of protection of the premises supply and all appliances thereof, against damage arising in any manner from the use of the water supply, variation of water pressure or any interruption of water supply; particularly, must such owner or occupant protect water cooled compressors for refrigeration systems by means of high pressure safety cutout devices. There shall likewise be provided means for the prevention of the transmission of water ram or noise of operation of any valve or appliance through the piping of their own or adjacent premises.
(B) On all “closed systems” (i.e., systems having a check valve, pressure regulator or reducing valve, water filter or softener) an effective pressure relief valve shall be installed either in the top tapping or the upper side tapping of the hot water tank, or on the hot water distributing pipe connection at the tank. A one-half inch drain pipe shall be connected to the relief valve for discharge on the floor or into a sink or open drain. No stop valve shall be placed between the hot water tank and the relief valve or on the drain pipe.
(C) An air chamber or approved shock absorber shall be installed at the terminus of each riser, fixture branch or hydraulic elevator main for the prevention of undue water hammer. The air chamber shall have a diameter not less than that of the pipe it serves and a length not less than 15 diameters of said supply pipe. Where possible, the air chamber should be provided with a valve and drain cock at its base for water drainage and replenishment of air.
(2005 Code, § 104.121)