Pressure Relief Valve should never be installed in

• A. In Series
• B. In Parallel
• C. On the discharge line
• D. On the suction line

Answer: (A)

A pressure relief valve is meant to provide a bypass for excess pressure, returning flow to the reservoir and keeping the protected portion of the circuit from overpressurizing. It must be connected in parallel to the load it protects so that when the pressure rises above its setting, the valve opens and diverts flow away from the critical path.

If the valve is placed in series with the flow, it sits directly in the path of the normal load. When the pressure reaches the setpoint, the valve may begin to open, but it can only affect the downstream side. The upstream portion of the circuit would still experience high pressure, so the protection of the component ahead fails. It can also create unnecessary flow restriction and unpredictable behavior.

That’s why a relief valve should never be installed in series. The typical, safe placement is in parallel on the high-pressure side, often discharging back to the tank; placing it on the suction line is avoided because it can cause cavitation or loss of prime.