Which test is used to blow out the pilot?

• A. Purge
• B. Drop out
• C. Vent test
• D. Pilot blow

Answer: (B)

The test you use to blow out the pilot is the drop out test. In a gas-fired system, the pilot flame is held open by a small millivolt signal from the thermocouple. If the pilot goes out, that signal stops, and the valve is designed to shut off automatically. The drop out test simulates a flame-out by extinguishing the pilot and then checking that the safety mechanism promptly closes the gas supply, preventing unburned gas from continuing to flow.

This is different from purge, which clears residual gas from a line before service; vent test, which checks the venting of combustion products; or a pilot blow, which isn’t a standard test term. The purpose of this test is specifically to verify the flame-out safety response.