| 摘要 |
A diaphragm operated valve includes a valve body having inlet, outlet and bypass ports in it. A diaphragm assembly includes a flexible diaphragm and a valve stem. The valve stem has a main valve member attached to it which is movable with the diaphragm assembly. The diaphragm is flexibly responsive to negative pressure which regulates main valve member operation. The valve includes a fail safe feature which shuts the main valve passage upon loss of negative pressure. The diaphragm assembly and main valve function to regulate air output from the valve. A second pressure relief valve member is carried by, but operates independently of the valve stem. Means for limiting air output of the main valve during high air input conditions is carried on the pressure relief side of the valve and operates whenever the pressure relief valve is activated so as to aid in the closure of the main valve passage.
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