How does a safety valve operate?

A safety valve operates by expelling excess steam pressure from the boiler, which is essential for maintaining safe operating conditions. When the pressure inside the boiler exceeds a predetermined limit, the safety valve automatically opens to release steam, thereby reducing the pressure back to a safe level. This mechanism is crucial for preventing potential hazards such as boiler explosions caused by excessive pressure build-up.

The action of the safety valve is a critical safety feature in steam boilers, ensuring that the system operates within its designed pressure limits. This response is automatic and ensures that the pressure does not reach dangerous levels, safeguarding both the equipment and personnel.

The other options do not accurately describe the function of a safety valve. Maintaining a constant pressure in the boiler, controlling the feed-water supply, or restricting flow under high pressure conditions are functions that might pertain to other components within the boiler system, such as pressure regulators or feedwater control valves. However, they do not reflect the primary role of the safety valve, which is specifically to release excess pressure.