Which statement is true about pressure relief valves in refrigeration systems?

Which statement is true about pressure relief valves in refrigeration systems?

• A. They should never be installed in series
• B. They must always be installed in series
• C. They should be placed on the discharge line
• D. They should be placed on the suction line

Answer: (A)

Overpressure protection relies on a pressure relief valve to vent refrigerant when the system exceeds its safe pressure. Placing valves in series is not a good idea because it makes the relief behavior unpredictable and can weaken protection. If two valves share a path, one valve’s opening can alter the pressure seen by the other, so you can end up with a situation where one valve vents first, the other never reaches its set point, or the overall venting capacity is not reliably matched to the actual overpressure. That ambiguity defeats the purpose of having a safety device. The safer practice is to give each high‑pressure area its own properly sized relief device with a clear vent path, often on the high‑pressure (discharge) side of the component, not on the suction line. This ensures immediate, predictable protection when overpressure occurs.

Overpressure protection relies on a pressure relief valve to vent refrigerant when the system exceeds its safe pressure. Placing valves in series is not a good idea because it makes the relief behavior unpredictable and can weaken protection. If two valves share a path, one valve’s opening can alter the pressure seen by the other, so you can end up with a situation where one valve vents first, the other never reaches its set point, or the overall venting capacity is not reliably matched to the actual overpressure. That ambiguity defeats the purpose of having a safety device.

The safer practice is to give each high‑pressure area its own properly sized relief device with a clear vent path, often on the high‑pressure (discharge) side of the component, not on the suction line. This ensures immediate, predictable protection when overpressure occurs.