Medical air compressor systems shall have a pressure relief valve set at ______percent above line pressure.

• A. 40
• B. 30
• C. 50
• D. 20

Answer: (C)

Relieving overpressure is the job of the pressure relief valve in a medical air system. It should remain closed during normal operation but open when pressure climbs enough to endanger equipment or patient care. Setting the valve at fifty percent above line pressure gives a safe margin: it won’t trip during usual fluctuations, but will vent excess if pressure rises well beyond the operating level. For example, with a typical line pressure around 50 psig, the valve would open near 75 psig, preventing a dangerous surge. If the setting were much lower, it could vent too often and waste gas or cause interruptions; if it were much higher, it could allow dangerous pressure rises before relief occurs. Fifty percent above line pressure balances protection with reliable supply.