Which device detects the flame in a natural draft gas fired boiler?

The flame detector is specifically designed to sense the presence of a flame in a natural draft gas-fired boiler. It operates by monitoring the electromagnetic spectrum emitted by the flame. When a flame is present, the detector generates a signal that can indicate to the control system that combustion is occurring safely. This is an essential safety feature, as it helps prevent situations where gas could be released without a flame present, reducing the risk of explosions or other safety hazards.

In this context, the flame detector serves a critical role in the operation of the boiler, ensuring that the combustion process is both efficient and safe. Other devices such as the main gas valve, ignition transformer, and load relay have specific functions related to gas flow control, ignition, and electrical load management, but they do not directly detect the presence of flame like the flame detector does.