| 摘要 |
<p>1,220,467. Valves. BRYAN DONKIN CO. Ltd. 6 March, 1969 [11 March, 1968; 4 June, 1968], Nos. 11818/68 and 26654/68. Heading F2V. In a valve which is adapted to regulate pressure when such pressure lies between predetermined upper and lower values, and to cutoff flow when such pressure rises above, or falls below, the predetermined values, or when a diaphragm which operates the valve in response to outlet pressure acting thereon becomes ruptured, regulation of pressure is effected by a valve member 32 whilst cut-off is effected by a valve member 34, the two valve members being interconnected by a spindle 36 and co-operating with respective ends of a bore interconnecting the inlet 12 and outlet 14. An extension 30 of the spindle 36 is connected, through an operating lever 86, a trip lever 70 and a link 72, to a diaphragm 44 the underside of which is subjected to outlet pressure, the operating lever being pivoted at 94, and the trip lever being pivoted to lever 86 at 78 and to link 72 at 76. A spring 80 extends between the pivot point 76 and a pin 82 and, under normal regulating conditions, extends below pivot point 78. With the fluid pressure within the predetermined values, the pressure at the outlet 14 acts on the diaphragm which correspondingly actuates valve member 32. Upon such pressure falling below the lower value, spring 52 moves the diaphragm downwardly and hence, via the levers and link, moves valve member 34 on to its seat. In the event of the pressure exceeding the upper value, diaphragm 44 moves upwardly with the result that valve member 32 is seated. Subsequent and further movement of the diaphragm in the same direction, causes spring 80 to move to the other side of pivot 75 and hence, by virtue of the arrangement of pivot points and the spring tension, results in valve member 32 becoming unseated and valve member 34 seated. In the event of the diaphragm becoming ruptured, the outflow from diaphragm chamber 45 results in a pressure differential being created across a spring-loaded valve member 104, which in combination with a seat 102 affords a restricted passage between outlet 14 and chamber 48, and hence in valve member 104 being seated at 102. The resulting decrease in pressure within chamber 48 results in diaphragm 44 moving downwardly and the valve experiencing a "low-pressure cut-off." In modifications (Figs. 2 to 4, not shown), the restricted flow between the outlet and the diaphragm chamber takes place either through an an aperture formed in a spring-loaded valve member or between a two-part valve member (Fig. 4) and its seat, the cut-off initiated by such valve members being of the "high-pressure cut-off" type as the valve members open and so provide a relatively unrestricted flow between the outlet and diaphragm chamber upon the diaphragm becoming fractured.</p> |
