Which device is used to control flame in a boiler?

The device used to control flame in a boiler is flame controls. Flame controls are essential components that ensure the safe and efficient operation of a boiler by regulating the flame according to the required parameters for the combustion process. They monitor the presence of a flame and, if it goes out, will shut down the fuel supply to prevent unsafe conditions, thus maintaining safety.

Flame controls can include systems such as flame sensors, ignition systems, and safety shutoff valves. Their primary function is to provide a reliable way of managing the combustion process, which is crucial for maintaining the right temperature and pressure within the boiler.

Other devices mentioned serve different purposes in a boiler system. A thermostat is primarily used for regulating temperature, flow switches are designed to monitor the flow of liquid, and pressure relief valves are safety devices that release pressure to prevent damage to the boiler. While all these components are important for the overall operation of a boiler, their functions are distinct from the specific task of controlling the flame.