How quickly must a flame detector in an industrial boiler detect loss of flame?

A flame detector in an industrial boiler is a critical safety device responsible for monitoring the presence of a flame throughout the combustion process. In the event of a flame failure, it is vital that the detector responds quickly to prevent dangerous conditions, such as the possibility of unburnt fuel accumulating, which could lead to an explosion or other serious hazards.

The correct answer reflects that a flame detector should ideally detect loss of flame within 4 seconds. This response time is generally established based on industry safety standards and practices to ensure that the boiler system can immediately respond to a flameout and safely shut down. The 4-second window allows sufficient time for the detector to ascertain the presence or absence of the flame, signaling the boiler controls to initiate safety mechanisms that may involve shutting down the fuel supply or activating alarms.

A quicker detection time, such as within 1 or 2 seconds, may seem advantageous but could lead to false alarms or unnecessary interruptions if the flame flickers momentarily due to benign conditions. Conversely, a slower detection time, such as 6 seconds, may increase the risk of hazardous situations, highlighting the need for a balance between responsiveness and reliability in flame detection systems.