Patent GB-825946-A (GB)
Title: Fluid-control valves
IPC: F16K31/126
Filed: 1956-05-22
Abstract: 825,946. Valves. FREEMAN, M. L. May 22. 1956, No. 15772/56. Class 135. The valve body 10, Fig. 1, which has inlet and outlet compartments 12, 13 is provided with a lower valve seat 18 that supports a lower sleeve 19 upon which rests an upper valve seat 20 that supports an upper sleeve 21; the assembly is held in place by a bonnet 22. " 0 "- rings 24, 25, form seals between the body and valve seats and the bonnet. Fluid from the inlet 11 may either flow to a lower outlet 30 via aperture 27 in sleeve and seat 18, or to a side outlet 33 through apertures 29 in sleeve 21 and seat 21; plug valves 31, 34 control the seats 18, 20, the valve 34 having a cylindrical stem 35, slidable on the stem of the lower valve 31. A resilient bellows 38 which interconnects the valves 31, 34 is sealed thereto by " 0 "-rings 39, 42, the controlled fluid and the bellows tending to bias the valves on to their seats. The stem 35 is closed by a cap 44 sealed by an "O"-ring 45 whilst packing 46 is compressed by a nut in a space between the bonnet and stem 35. The upper end of the stem 32 is provided with a stop 49 in the bore 50 of an operator 51, a ring 52 in the bore 50 engaging the stop 49 upon upward movement of the operator to lift the stem 32 against the resistance of the bellows 38. Downward motion of the operator 51 causes the ring 52 to engage the cap 44 and open valve 34 against the bellows resistance. The operator 51 may, as shown, be actuated either by admitting fluid to one or other side of diaphragm 60 or simultaneously to both sides thereof, to move the operator by the differential of such pressures. In a modification (Fig. 2, not shown) a spring is housed within the bellows to reinforce the action of the latter; fluid may also be confined in the bellows. In another modification (Fig. 3, not shown) the lower valve is secured on the stem by a nut, an "O" sealing ring being interposed therebetween as well as between the solid and hollow stems of the lower and upper valves, respectively; a spring outside the valve body and between the outer ends of the stems urges the valves to the closed position. The upper valve is retained on its hollow stem by a snap ring, the stem being sealed with respect to the bonnet, through which it passes, by " 0 "-rings; the hollow stem may be locked by a nut to prevent the upper valve from opening. The valve is actuated by admitting fluid above or below a double-diaphragm assembly; the lower valve may be prevented from opening by a wedge or cam, not shown, engaging its stem. In another modification (Fig. 4, not shown) the upper valve is slidable over the stem of the lower valve, the two valves being interconnected and urged on to their seats by a spring in a slidable sleeve whilst each valve is operated by a separate diaphragm. Both valves may be simultaneously opened and the degree of displacement of each valve is controlled by its diaphragm; either valve may be closed whilst the other is opened. In a further modification, both valves 130, 134, Fig. 5, are slidable on the stem 160 and urged on to their seats by the spring 135 disposed in a slidable sleeve 137, the stem 160 being connected to the double diaphragm 168. The diaphragm housing is sealed to the bonnet 166 by set screws 169 and the stem 160 is sealed to the bonnet by " 0 "-rings 170. Upon introducing fluid above the diaphragms 168 the stem 160 is lowered and slides through the valves 130, 134 until a shoulder 162 engages the upper valve 134 to open the latter; when fluid acts below the diaphragms the stem 160 is lifted until a nut 161 engages and then unseats the lower valve 134. In the embodiments of Figs. 3, 4 and 5 flanges are provided on the valve member to aid the controlled fluid in urging the valves on to their seats; the flanges may serve as safety means for automatically closing the valves when excess flow velocities occur or on failure of the actuating mechanism. The size of the bellows or sleeve determines the force necessary to open the valve. In a final embodiment (Fig. 6, not shown) the inlet and outlet chamber are located one above the other and the valves are arranged as in Fig. 5, but the spring sleeve is perforated to enable the controlled fluid to act over a greater area of the valves and so more forcibly urged them on to their seats. Downward movement of the double diaphragm opens the upper valve by means of a hollow stem around the main stem, the hollow stem not being connected to the diaphragm assembly. Upward movement of the main stem effects opening of the lower valve as in Fig. 5, since this stem is attached to the diaphragm. The latter are provided with an exteriorly extending plunger to indicate their position.