GB860622A - Improvements in or relating to liquid pressure actuated control devices for automatically switching on and off the heating means of liquid flow heaters - Google Patents

Abstract

860,622. Valves. JUNKERS & CO. G.m.b.H. May 16, 1958 [May 17, 1957], No. 15741/58. Class 135. A known liquid pressure actuated control device, Fig. 1, for automatically switching on and off the heating means of a water flow heater, e.g. by controlling the gas valve 31, and wherein the actuating member or diaphragm 12 of the control device, which is arranged in the casing thereof between a high pressure chamber 10<SP>1</SP> and a low pressure chamber 11<SP>1</SP>, is coupled to the regulating member 15 of a water regulating valve and is actuated by the suction effect of a Venturi tube 20 arranged in the water flow passage, the throat 20<SP>1</SP> of said tube communicating through a suction passage 21 with the low pressure chamber 11<SP>1</SP>, whilst a by-pass passage 27 branching off in the flow direction of the water downstream of the water regulating valve 15 but upstream of the Venturi tube and communicating again with the main water flow passage downstream of the Venturi tube, can be progressively restricted by a throttle valve 28 for regulating the temperature of the water to be extracted from an outlet tap 25, is improved in that the by-passage before communicating again with the main water flow passage, communicates with a chamber 44, Fig. 2, in which the water is subjected to a damming effect and which is connected both to the main water flow passage and to the suction passage of the Venturi tube. As shown, the chamber 44 communicates with the downstream end of the Venturi tube 20 through apertures 45 therein so as to provide the damming effect, and the damming pressure in this chamber is communicated, past a narrow annular gap 40 formed by a grooved collar 39 of the tube, to an annular chamber 36 surrounding suction apertures 35 of the Venturi, the area of the annular gap 40 being about half the total area of these suction apertures. Thus when a larger quantity of water of lower temperature is required to be extracted from the tap 25, the throttle valve 28 is gradually opened by hand and the increasing damming pressure acts to reduce the suction in passage 21 so that the diaphragm moves to further open the water regulating valve 15, whereby an additional quantity of water corresponding to the increasing opening of the by-pass valve 28 is allowed through by the water regulating valve 15.