Patent GB-226298-A (GB)
Title: Improvements in or relating to air and gas mixing apparatus for use in connection with gas burners
IPC: B01F23/10
Filed: 1923-09-25
Abstract: 226,298. Keith, G., and Keith & Blackman Co., Ltd., J. Sept. 25, 1923. Atmospheric gas burners; valve &c., arrangements &c. of.-Gas and air mixing apparatus, particularly for supplying the burners of ovens, comprises gas and air supply pipes connected to an injector, a governor for controlling the pressure of the induced constituent in a predetermined ratio to the mixture pressure, a manually adjustable obturator for regulating the flow of the governed constituent, and means for automatically adjusting a valve controlling the admission of the injected constituent to obtain a substantially constant mixture pressure. In one form, gas and air, preferably at a pressure exceeding the mixture pressure, are supplied through non-return valves and pipes 2, 3 respectively to an injector 1 and mixed in a Venturi tube 5 communicating with a chamber 6 piped to burners 7. The pipe 2 is fitted with a governor 9 and an obturator 11 to control the proportions of gas and air as described in Specification 16711/15, a ball valve 35 being provided in a pipe 10 leading to the chamber 6 and a spindle 32 passing through a floating washer 33 to protect the diaphragm 31 in the event of an explosion. The obturator 11 is adapted to close against the action of a spring 37 when subjected to back pressure and the pipe 2 is pro vided with a valve which closes on the operation of a trip 38, Fig. 5, by pressure due to an explosion acting on a spring-loaded piston 39 in a chamber 40 connected to the chamber 6. A spring-pressed valve 8 controlling admission . o air to the injector nozzle 4 is connected by a tubular rod 12, having ports 12<1>, 12<2>, to a dia phragm 13, or piston, in a chamber 14, the lowe compartment of which communicates, through, pipe 15 having a contraction 16, with the pipe 3 and the upper compartment, through a port con trolled by a ball valve 17, with the chamber 6 A pipe 24 leads from the lower compartment to a chamber 20, having an opening at or near the bottom, in a tank 18 filled with liquid up to closure 19 and containing an adjustable displace 25 for varying the liquid level. When the pres sure in the chamber 20 depresses the liquid leve below that required to sustain a float 21, the stem 22 of the latter opens a valve 23. In a modification, the liquid level in the tank 18<1> is varied automatically by means of a thermostat 27, Fig 3, which controls the outlet of a leakage tube 30 connected to the pipe 15 by a pipe 29, having a constriction, and to a closed vessel 28, the lower end of which is connected to the tank 18'. Accord ing to the first Provisional Specification, the valve 8 is connected by a rod to a float in a cylinder depending from the chamber 6 into, and having perforations below the liquid level in, a tank having a trapped overflow. The tank may be con nected with a second tank connected with the pipe 3 and having a leakage tube provided witl a valve controlled by a thermostat. In a modification, the diaphragm 13 is weighted and the tube 24 dispensed with, or the latter dips into a liquid seal, the level in which may be controlled by an additional tank and a thermostat.