Patent GB-840452-A (GB)
Abstract: 840,452. Valves. BRITISH THERMOSTAT CO. Ltd. Sept. 18, 1958 [Sept. 26, 1957], No. 30237/57. Class 135. A float chamber 1, Fig. 1, is supplied with fuel under the control of an inlet valve 2, Fig. 3, actuated by a lever 5 carried by a main float 3; an auxiliary float 4 in a separate chamber 8 is supplied with fuel from the chamber 1 when the latter overflows, the float 4 being supported by a lever 9 having a catch co-operating with another lever 12 pivoted in a pair of notches 13, Fig. 1, against which it is held by a spring 14 acting on a vertical lever 15 formed as an extension of the lever 12; the lever 15 projects through the lid 16 and is rocked clockwise to release the valve 2. When fuel overflows into the chamber 8 the float rises and rocks the lever 9 anticlockwise to cause the catch 11 to release the lever 12 which is then urged anticlockwise by the spring 14, the middle of the lever 12 then abuts and closes the valve 2. The fuel passes to the valve 2 via a filter, a spring-loaded valve shutting off the fuel flow automatically when the filter is removed for cleaning. Mounted in a block 21 in the chamber 1 are two adjustable and spring-loaded restrictors 22, 23 each embodying an external thread affording a flow path the degree of restriction of which depends upon the amount each restrictor penetrates its recess in the block; such penetration is determined by adjustment of screws 24, 25. Further screws are provided as stops to limit the maximum adjustment. A rotary-disc valveclosure member 30 is spring urged into engagement with the underside of the block 21, the disc being rotatable by a spindle 32 passing through a bearing tube 33 in the centre of the block 21; the upper end of the spindle 32 carries a knob and pointer co-operating with a scale not shown, providing "off," "low flow " and "high flow range." The block 21 is part of a chamber 34 from which fuel flows to an appliance via a screw 35 which upon being removed enables the restrictors and disc valve to be withdrawn as a unit for cleaning. The disc 30 incorporates concentric grooves 36, 37, Fig. 6, the groove 36 having a gradually increasing depth and communicating with the recess containing the " high-flow " restrictor 22 whilst groove 37 communicates with the recess containing the "low flow" restrictor 23; the groove 37 may have a variable cross-section to provide a " low flow range." Each groove opens by a port 1 with the chamber 1. In the "off " position the disc 30, Fig. 1, prevents passage of fuel to the restrictors whilst in the " low flow " position only restrictor 23 is supplied with fuel; in the " high flow range " position the groove 36 is placed in series with the restrictor 22 and fuel flow is determined by the sum of the resistances offered by latter and the length of groove 36. A pin on the spindle 32 co-operates with a stop in the form of a bolt securing a bracket carrying screws 24, 25; upon moving the spindle 32 into the " off " position the pin strikes a part 45 of the lever 12 and rocks the latter out of one of the notches 13 so shutting the inlet valve 2. The grooves 36, 37 may be disposed in the underside of the block 21 and the disc 30 may be replaced by a reciprocating member. The restrictors 22, 23 may comprise an axial groove. An additional thermostatically operated valve, not shown, may be mounted in or associated with the recess containing the restrictor 22. Specification 779,201 is referred to.