GB1421376A - Forced air draught gas burning appliances - Google Patents

Abstract

1421376 Igniters; forced draught gas burners DUNLOP Ltd 6 April 1973 [17 April 1972] 17550/72 Headings F4F and F4T A forced air draught gas burner comprises a main burner 2 having a fuel gas supply pipe 15 and a forced air draught supplied, e.g. by an electric fan, through duct 1, an ignition arrangement comprising ignition means (7), Fig. 2 (not shown), projecting into the combustion zone of a pilot burner 10, 14 for ignition thereof, the pilot burner communicating with duct 1 and being arranged so that pilot fuel gas supplied by pipe 5 is only carried into the pilot burner combustion zone if the forced air draught is present, and a pilot burner flame detector (8) arranged to control fuel gas supply to the main burner. On start-up of the burner a fan is energized and the first stage of a two-stage fuel gas valve is activated to supply gas to the pilot burner; this gas being carried into the pilot burner combustion zone by part of the air draught entering burner tube 10 via holes 11, 12. If the draught is absent the pilot fuel gas entering tube 10 via low permeability foamed metal plug 6 passes out of hole 12 and no pilot flame results. Normally, however, the fuel gas reaches the pilot combustion zone and is ignited by an ignition probe (7) connected to a high tension source, the pilot flame being detected by ionization probe (8) which thus actuates the second stage of the fuel valve to supply fuel gas to main burner 2 for ignition by the pilot burner. If the pilot flame goes out, e.g. due to air draught failure, the probe (8) causes the fuel valve to stop supplying main burner 2. The pilot burner has a tube 10 of rectangular section.