What component of the boiler is critical for preventing water loss during pressure loss?

The check valve plays a vital role in preventing water loss during pressure loss in a boiler system. This valve allows fluid to flow in one direction while preventing backflow in the opposite direction. In the event of a pressure drop within the boiler, the check valve ensures that the water remains contained within the system and does not escape, thereby maintaining system integrity and preventing damage caused by loss of water.

In contrast, the other components listed serve different functions. The pressure gauge is used for monitoring the pressure within the boiler but does not influence water retention. The blow-off valve is meant for expelling boiler water and sediments, and it could contribute to water loss if opened. The feedwater pump is responsible for supplying water to the boiler but does not prevent water from escaping during a pressure loss situation. The check valve, therefore, is crucial for maintaining the required water levels and pressure stability in the boiler system.