To protect a large compressor against excessive compressor discharge pressure we could use:

To protect a large compressor against excessive compressor discharge pressure we could use:

• A. A fusible plug
• B. Either a fusible plug or a rupture disc
• C. A spring-loaded pressure relief valve
• D. A magnetic check valve

Answer: (C)

The idea being tested is overpressure protection that can respond automatically and repeatedly. A spring-loaded pressure relief valve is designed to vent gas when the discharge pressure exceeds a preset limit and then reseal once pressure drops back down. This makes it ideal for a large compressor, where you want ongoing protection without needing to replace parts after each relief event. The spring holds the valve closed until the set pressure is reached; when released, the valve opens to relieve, and as pressure falls, the spring re-closes it, ready for the next surge. Fusible plugs rely on temperature and aren’t precise for controlling pressure, and they’re not resettable in normal operation. Rupture discs provide a one-time release and must be replaced after each event, so they don’t offer ongoing protection. A magnetic check valve prevents backflow rather than relieving excess pressure, so it doesn’t serve the same protective purpose.

The idea being tested is overpressure protection that can respond automatically and repeatedly. A spring-loaded pressure relief valve is designed to vent gas when the discharge pressure exceeds a preset limit and then reseal once pressure drops back down. This makes it ideal for a large compressor, where you want ongoing protection without needing to replace parts after each relief event. The spring holds the valve closed until the set pressure is reached; when released, the valve opens to relieve, and as pressure falls, the spring re-closes it, ready for the next surge.

Fusible plugs rely on temperature and aren’t precise for controlling pressure, and they’re not resettable in normal operation. Rupture discs provide a one-time release and must be replaced after each event, so they don’t offer ongoing protection. A magnetic check valve prevents backflow rather than relieving excess pressure, so it doesn’t serve the same protective purpose.