| 摘要 |
A relief valve (10) having both spring biasing means (116) and air pressure biasing means (114). The spring biasing means (116) includes a plurality of spring washers (132) acting between the valve body (12) and a valve member (74). The air biasing means (116) includes an air cylinder defined by an intermediate portion (20) of the valve body (12), and a piston (118) disposed within the cylinder and acting on the valve member (74). An air inlet port (48) is provided above the piston (118) to permit the area above the piston (118) to be pressurized to add to the biasing force of the spring biasing means (116), and an air inlet port (52) is provided below the piston (118) to permit the area below the piston (118) to be pressurized to open the valve manually for testing and exercising. A "quiet" element (102) surrounds the valve member (74) to reduce the sound level of the fluid flowing through the valve when the valve opens.
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