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Washington Administrative Code (Last Updated: November 23, 2016) |
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Title 296. Labor and Industries, Department of |
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Chapter 296-96. Safety regulations and fees for all elevators, dumbwaiters, escalators and other conveyances. |
Section 296-96-23318. What requirements apply to pump relief valves?
Latest version.
- (1) Each pump or group of pumps must be equipped with a relief valve conforming to the following specifications, except as covered by subsection (2) of this section:(a) The relief valve must be located between the pump and the check valve and must be of such a type and installed in the by-pass connection so that the valve cannot be shut off from the hydraulic system.(b) The relief valve must be preset to open at a pressure no greater than 125 percent of working pressure.(c) The size of the relief valve and bypass must be sufficient to pass the maximum rated capacity of the pump without raising the pressure more than 20 percent above that at which the valve opens. Two or more relief valves may be used to obtain the required capacity.(d) Relief valves having exposed pressure adjustments, if used, must have their means of adjustment sealed after being set to the correct pressure.(2) No relief valve is required for centrifugal pumps driven by induction motors, provided the shutoff, or maximum pressure which the pump can develop, is not greater than 135 percent of the working pressure at the pump.