Flammable vapor control system for devices with standing pilot flame
AssigneeInvensys Robertshaw Controls Company
InventorsAnthony W. Abraham, Raymond Joubran, Kenneth Minkler
Life of this patent
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Abstract
A safety device for shutting off the flow of gas to a gas-fired appliance in the presence of flammable vapors. A flammable vapor sensor is inserted in the circuit supplying a solenoid actuated valve with power from a thermocouple. The sensor responds to the presence of a flammable vapor with an increase in resistance. When a critical concentration of flammable vapors is achieved, the voltage drop across the sensor causes the solenoid actuated valve to close.
Claims16
A fuel control system for controlling a burner of a gas-fired appliance, employing a standing pilot flame, comprising:
- a gas valve for controlling the flow of gas to said appliance;
- a sensor operative to detect a flammable vapor;
- an electrical circuit operative to close the gas valve in the event a preselected concentration of said flammable vapor is sensed by said sensor.
A method of adapting a flammable vapor sensor to a valve control circuit employing a solenoid mechanism including a coil to hold a valve in an open position, and a thermocouple to power said solenoid mechanism when said thermocouple is exposed to a standing pilot flame, comprising the steps of:
- inserting a variable resistance flammable vapor in series between said thermocouple and said solenoid mechanism;
- adjusting the resistance of said coil to provide for a sufficient current flow through the sensor and coil to enable said solenoid mechanism to hold said valve in its open position when flammable vapors below a preselected level are sensed.
Dependencies are inferred from the claim text.