GB395964A - Improvements in or relating to gas-heated appliances - Google Patents

Abstract

395,964. Thermally-controlled valves. BOSCH AKT.-GES., R., 4, Militõrstrasse, Stuttgart, Germany. Jan. 26, 1933, No. 2483. Convention date, Feb. 17, 1932. Addition to 384,200. [Class 135.] In a gas-heated appliance according to the parent Specification, in which a backdraught causes extinction of a " guardian " flame burner 29, from which results the closure of the valve 23 controlling the gas supply to the main burner, the arrangement is such that the guardian flame is extinguished by a small current of the burnt gases from the combustion chamber, which is caused to branch off from the main current at a point where an excess pressure prevails only when a back-draught occurs. In this way failure to extinguish the guardian flame owing to admixture of oxygen with the waste gases, such as might occur during a strong backdraught, is avoided. In the geyser shown in Fig. 5, a down-draught produces an increase of pressure which causes burnt gases not mixed with air to be diverted down a pipe 43 opening into the top of the back-draught diverting hood 12, these gases being conveyed to the flame of the burner 29 to extinguish it. 'A hood 45 may be arranged over the opening to the pipe 43 to aid in preventing admixture of air passing down the flue with the gases entering the pipe 43. To aid the gravitational descent of the gases to the burner 29, the pipe conveying them may be cooled by air or water, and may be protected from the heat-emitting parts of the apparatus by a partition and air space. To prevent extinction of the burner 29 by short intermittent back-draughts, the pipe may comprise an enlarged portion, formed in the case shown by a flat elongated box 49, which retards the delivery of the burnt gases to the burner. Fig. 7 shows a construction of the guardian-flame burner, comprising a valve 32 which is pressed on to its seating to cut off the gas supply by means of a diaphragm 31 acting through a spring 61. When the diaphragm is heated it curves and raises the valve. The extinguishing gases are conveyed to the burner through a flexible pipe 64 connected to a cover 65 mounted on the burner and having a central aperture 67 for the flame. A gas heater is described in which the gas valve of the main burner is operated by a thermostat heated by the flame of the guardian burner, and closes when the latter burner is extinguished.