(1) Valves, piping and fittings shall not be subjected to working pressures that exceed manufacturer recommendations.
(2) Pipes, especially those that may vibrate, shall be sufficiently supported at each joint and fitting so undue stress is eliminated.
(3) A shut-off valve shall be installed in the pit.
(4) Each pump shall be equipped with a relief valve and all relief valves shall be:
(a) Located between the pump and check valve in a bypass connection;
(b) A type that cannot be shut off from the hydraulic system; and
(c) Preset to open at a pressure not greater than 125 percent of the working pressure at the pump.
EXCEPTION: | Relief valves are not required for centrifugal pumps driven by an induction motor when the shutoff or maximum pressure that the pump develops is no more than 135 percent of the working pressure at the pump. |
(5) A check valve shall be installed that will hold a car and its rated load at any point whenever a pump stops or pump operating pressure drops below the required minimum.
[Statutory Authority: Chapter
70.87 RCW. WSR 18-18-070, § 296-96-24770, filed 8/31/18, effective 10/1/18.]