A flame sensing relay strategy that takes advantage of the ionization of flame is called

A flame sensing relay strategy that takes advantage of the ionization of flame is called

• A. Thermocouple
• B. Flame rod
• C. Ion sensor
• D. Cad cell

Answer: (B)

The idea being tested is sensing flame presence through the ionization produced in a flame. A flame rod is a small electrode placed in the flame; when the flame exists, ions in the combustion products conduct current between the rod and the circuit. The control system uses this ionization current as a proof that the flame is present; if ionization drops (no flame), the circuit detects the loss of current and can shut off the gas for safety. The other options rely on different mechanisms: a thermocouple detects flame heat to generate a small voltage, a cad cell responds to flame light, and an ion-sensor term is less specific to flame ionization. Thus, the flame rod is the device that takes advantage of flame ionization.

The idea being tested is sensing flame presence through the ionization produced in a flame. A flame rod is a small electrode placed in the flame; when the flame exists, ions in the combustion products conduct current between the rod and the circuit. The control system uses this ionization current as a proof that the flame is present; if ionization drops (no flame), the circuit detects the loss of current and can shut off the gas for safety. The other options rely on different mechanisms: a thermocouple detects flame heat to generate a small voltage, a cad cell responds to flame light, and an ion-sensor term is less specific to flame ionization. Thus, the flame rod is the device that takes advantage of flame ionization.