GB425978A - Safety arrangements for obviating all danger of asphyxiation by or explosion of gas and other applications - Google Patents

Abstract

<PICT:0425978/III/1> Means for cutting-off a gas supply in case of leakage and/or for giving warning of such leakage or of fire comprises an electric switch which is closed when escaping gas comes into contact with platinum black, a relay in circuit with the switch, and a valve in the gas supply conduit adapted to be closed by the relay. The switch consists of a U-tube 3 with circuit wires 5<1>, 5<2>, and bulbs 4<1>, 4<2> containing hydrogen. Elements 10, of platinum black are associated with the bulb 4<1>. If gas escapes from the service piping 13<1>, the elements 10 heat the bulb 4<1> so that the mercury moves and closes the circuit. The electromagnet 7 then swings a pivoted latch 19, allowing a spring 17 to raise a plunger 16 and so rock a lever 14 to close a valve 2 in the supply pipe 13. The switch is enclosed in a gauze casing. In a modification, the lever 14 carries a part-spherical plug for sealing the point where the lever emerges from the pipe 13, and a spring is applied directly to the valve 2. In another modification, the free end of the lever 14 acts as the moving iron of the relay, and is locked in valve-closing position by a spring bolt. In another modification, a secondary circuit including an audible alarm is arranged in parallel with the relay 7. In another modification, Fig. 6, a switch 4<1>, 4<2>, 3 is used for giving an alarm only in case of gas leakage or for indicating the presence of fire-damp in mines. In a modification of this arrangement, Fig. 7, (not shown), the bulb 4<2> is enclosed in heat insulation, so that arrangement can serve also as a fire alarm.