573,190. Subaqueous burners. SUBMERGED COMBUSTION CO. OF AMERICA, INC. Aug. 21, 1943, No. 13670. Convention date, April 5. [Classes 75 (i) and 75 (iii)] [Also in Group XXXVII] The fuel supply and ignition means of a submerged combustion burner are controlled by motor-actuated timer means controlled by the temperature of the liquid to be heated. The burner may be that described in Specification 500,295. Fig. 1 shows a burner 2 discharging combustion gases through holes 12 in an L, T. or U-shaped casing 8 into a tank 4 containing the liquid to be heated. The burner 2 comprises an outer main gas supply passage 14, an intermediate main air supply passage 16, and a central passage 18 for the supply of pilot gas and air for the ignition of the gas and air issuing through an apertured burner plate 22. Air is supplied by a constantly running blower 24 through a pipe 40 to the passage 16, a portion of the air being conducted to the passage 18 through a pipe 38 fitted with a control valve 42 and a metering orifice 46. The gas is supplied either at high pressure or by a compressor 52 through pipes 62, 68 to the passage 14, the gas and air pressures being equalized by a by-pass governor 50. A solenoid-actuated valve 70 and metering orifice 72 are fitted in the pipe 68. A portion of the gas is conducted through a conduit 64 controlled by a solenoid-actuated valve 66 to the passage 18 where it is ignited by an electrically heated wire 20 supplied by a constant current transformer 96. A thermostatic element 100 in the liquid to be heated is connected to a switch 104 in the circuit of a timer motor 122, Fig. 2. The closure of a starter button switch 106 energizes a solenoid M to close contacts Ml, M2, M3 in the circuit of the blower motor 114 and contacts M4 in the circuit of the: timer motor 122. If the switch 104 is closed the. motor 122 revolves and the contacts T1, T3 are closed. A relay switch 1CR then operates contacts 1CR1 1CR2 to close the igniter circuit and a relay 1SR in the igniter circuit closes contacts 1SR1. thereby completing the . circuit to a relay 2CR and the solenoid actuating the pilot gas valve 66. The.relay 2CR closes contacts 2CR1 in the pilot gas valve circuit and contacts 2CR2 in the circuit of the main gas valve 70. The motor 122 then closes contacts T2 so that the gas valve 70 is opened. After ignition of the main burner . flame further revolution of .the motor 122 opens the contacts Tl, T3 and contacts T in its own circuit. The motor 122 is thereby stopped and the ignition circuit de-energized while the pilot and main burner valves remain open. Safety switches P1, P2 opening if the gas pressure falls are arranged in the circuit of the gas valve 70. Combustion normally continues until the switch 104 opens when the fuel supply system shuts down, the air supply system continuing to operate. Fig. 3 shows a suitable timer mechanism for the switches T, T1, T2, T3 which are initially held open by a latching device LA. When the circuit to the timing motor R is closed a coil G is energized to unlatch the switches and to close a clutch CL by which the motor drives a shaft SH clockwise to turn cams C, C1 .... C7 operating the switches in the required order. When the motor circuit is broken the shaft remains stationary until the circuit to the coil is broken. The latch bar and shaft are then returned to their mitial positions by springs S1, S2.