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CONTROLLING AND MONITORING COMBUSTIBLE GASES

  • US 3,766,441 A
  • Filed: 05/08/1970
  • Issued: 10/16/1973
  • Est. Priority Date: 05/09/1969
  • Status: Expired due to Term
First Claim
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1. Apparatus for monitoring and controlling the flow of a combustible gas comprising, an alternating current supply, a gas valve operated by a solenoid for controlling the flow of gas to a burner, a semiconductor thyristor switch having a control electrode, means connecting the switch in series circuit with the solenoid and the AC supply so that the switch controls the flow of current from the AC supply to the solenoid, means for monitoring the ionization current that flows through the burner gas flame when the gas is ignited, circuit means coupling said monitoring means to said control electrode and responsive thereto so as to trigger the switch into conduction when the gas is ignited and to inhibit the triggering thereof in the absence of a flame whereby the solenoid is operated to close the gas valve and cut off the gas flow to the burner, and said circuit means includes a phase advance circuit connecting said control electrode to the AC supply thereby to trigger said thyristor switch from said AC supply.

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