Patent GB-665861-A (GB)
Title: Improvements in or relating to gas burners
Inventor: MACCORMAC MICHAEL
IPC: G01N31/12
Filed: 1949-02-14
Abstract: Apparatus responsive to a change in the composition of a combustible gas comprises <PICT:0665861/III/1> a first burner tube 12 provided at its upper end with a flame-arresting device, a second burner tube 24 surrounding the first burner tube and closed at its lower end but open at its upper end, and an air inlet to the first burner tube so adjusted that when the composition of the combustible gas is normal the flame burns at the open end of the second burner tube but when the composition of the gas is altered the flame strikes back to the first burner tube and operates indicating, recording or warning means or means for controlling apparatus producing or employing the combustible gas.  The apparatus may be used for exapmle to put out of action an electro-detarrer when the oxygen content of the gaseous mixture undergoing treatment is dangerously close to the explosive range.  Gas is supplied by a pipe 14 and pressure governor 15 to a nozzle 20 the jets from which induce a flow of air through an inlet adjusted by a shutter 23 into a mixing tube 21 leading to the first burner tube 12 which is capped by a metal grid 22.  The second burner tube 24 makes an air-tight joint with the mixing tube 21 and has a ring 25 of refractory material at its upper end.  A loop of fusible wire 26 is arranged within the second burner tube so that it is melted when the flame strikes back and burns at the mouth of the first tube.  The fusible wire is carried by a replaceable unit comprising an outer silica tube 32 filled with refractory cement in which are embedded two small-bore silica tubes through which the fusible wire passes to terminals 29, 30 on a plug 35 secured to the outer silica tube. The fuse unit is inserted into a tube 33 let into the side of the second burner tube 24 and is held therein by a bayonet connection 36 between the plug 35 and a sleeve 37 on the tube 33, a rubber ring 38 between the plug and a shoulder on the tube 33 making an airtight joint.  The terminals 29, 30 are connected to a device controlling the operation of plant supplied with the same gas and to ensure that such plant is only operated when the flame is at the second burner tube the circuit includes a switch 39 closed by a bimetallic strip 40 heated by the flame at the second burner tube. The apparatus may be included in the "no volt coil" circuit of an electric blower supplying air to gas purifiers; if the apparatus is supplied with gas from a point close to the air inlet to the purifiers it ensures that the purification air is turned off if the gas supply to the purifiers is interrupted.  The apparatus may be used in conjunction with a solenoid valve to stop gas flow in an emergency.  A glass cylinder 16 and a cylindrical outer casing 17 of expanded metal for protecting the burner tubes are held between an upper ring 19 and a lower plate 18 each clamped to a supporting pillar 11.  The fusible wire may be replaced by a pair of electrodes so that the conductance of the flame gases may operate through a relay, a circuit including the controlling and indicating means.