| 摘要 |
A valve body is formed of a section of flow pipe for connection to an open end on a flow pipe by means of a surrounding sealing sleeve and outer clamp. A valve body end cap is formed of a standard pipe cap with inlet ports drilled through the end thereof. A valve seat member is centrally mounted on the inside of the valve body end cap having a valve seat on the end opposite the mounting end. The valve seat member has a first predetermined height for positioning the valve seat a predetermined distance above the inside surface of the end cap. An internal step is formed on the inside diameter of the end cap at a second predetermined height above the inside of the end cap. A spacing ring is placed on the internal step having a thickness to provide for a desired difference between the first predetermined height and the sum of the second predetermined height and the spacing ring thickness. A diaphragm formed to fit the inside diameter of the valve body end cap is positioned with one face in contact with the ring. The valve body is inserted into the valve body end cap to assume a position in firm contact with the other face of the diaphragm at the periphery thereof. The diaphragm has formed therethrough a centrally located pressure relief port. The center portion of the diaphragm is deflected by contact with the valve seat through an axial distance determined by the difference between the first and second predetermined heights and the thickness of the spacing ring. When the inside of the pressure relief valve is communicated with a closed flow path, a predetermined pressure differential across the diaphragm, with the higher pressure at the inlet ports, will urge the diaphragm through further axial deflection, thus lifting the diaphragm from the valve seat and communicating the differential pressures thereacross through the inlet port and pressure relief port until the pressure differential falls to or below the predetermined pressure differential.
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