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
Pressure Relief Valve vs Pressure Reducing Valve: What’s the Difference?
These two valves are often confused because their names sound similar and their bodies can look alike, but they do opposite jobs. One is a safety device that protects the whole system; the other is a control device that lowers pressure in one part of it. Getting them mixed up in a specification leads to a circuit that either is not protected or does not work. This guide makes the difference clear.
What is the difference between a pressure relief valve and a pressure reducing valve?
The short answer: a pressure relief valve is a safety device that is normally closed and opens only when pressure rises above a set limit, protecting the system by diverting excess flow. A pressure reducing valve is a control device that is normally open and throttles flow to hold a lower, steady pressure in a branch of the circuit. One caps the maximum pressure of the whole system; the other sets a lower pressure for one section.
Pressure relief valve (the safety device)
A pressure relief valve exists to protect the system from over-pressure. It is:
- Normally closed. It stays shut in normal operation and only opens when system pressure exceeds its set point.
- Sensed from its inlet. It responds to the upstream (system) pressure it is protecting.
- Positioned at the pump outlet or main line. It sets the maximum working pressure for the whole system, diverting excess flow (usually back to tank) to prevent damage.
Think of it as the circuit’s safety limit: under normal conditions you should not even notice it working.
Pressure reducing valve (the control device)
A pressure reducing valve exists to run part of a circuit at a lower pressure than the rest. It is:
- Normally open. It allows flow through until the downstream pressure reaches its setting, then throttles to hold that level.
- Sensed from its outlet. It regulates against the downstream (reduced) pressure it is maintaining.
- Positioned in a branch line, never the whole supply. It lowers pressure for one circuit while other branches keep running at full system pressure.
Think of it as a local regulator: it delivers a stable, reduced pressure to a section that needs less than the system maximum.
Side-by-side comparison
| Pressure relief valve | Pressure reducing valve | |
|---|---|---|
| Role | Safety (limits max pressure) | Control (maintains reduced pressure) |
| Normal state | Normally closed | Normally open |
| Senses | Inlet / upstream pressure | Outlet / downstream pressure |
| Location | Pump outlet / main line | Branch line only |
| Acts when | Pressure exceeds set point | Continuously throttles to hold set point |
How to specify the right one
Ask what the valve is for. If the goal is to protect the system or a component from over-pressure, you need a relief valve set at the safe maximum. If the goal is to run a branch at a lower working pressure than the rest of the system, you need a reducing valve set to that branch pressure. Then confirm flow rate, port standard, material and adjustment range so the valve matches the circuit.
The goal is the right valve for the job, whether you buy from us or not
We wrote this so you can tell a safety device from a control device and specify the right one, wherever you source it. Ask what the valve is for, protection or reduction, and the choice is clear.
If you do want it sourced to spec, here is how we work: Velqor supplies pressure relief and control valves as well as reducing configurations, engineered to your circuit rather than a fixed range. Give the function, set pressure, flow, port standard and material, and the valve is confirmed against your requirement, tested and documented. If a standard configuration covers your need, we will say so rather than over-engineer it.
Frequently Asked Questions
Is a pressure relief valve normally open or closed?
A pressure relief valve is normally closed. It stays shut during normal operation and opens only when system pressure rises above its set point, diverting excess flow to protect the system.
Is a pressure reducing valve normally open or closed?
A pressure reducing valve is normally open. It allows flow until the downstream pressure reaches its setting, then throttles to hold that lower pressure steady in the branch it serves.
Can I use a relief valve to reduce pressure in a branch?
No. A relief valve limits maximum pressure by diverting excess flow; it does not maintain a stable reduced pressure downstream. Use a reducing valve when a section of the circuit needs to run at a lower working pressure.
Where is each valve installed?
A relief valve is installed at the pump outlet or main line to cap the whole system’s pressure. A reducing valve is installed in a branch line so that one section runs at a lower pressure while other branches keep full system pressure.
Why do the two valves look so similar?
Both are pressure-controlled valves with comparable bodies and adjustment mechanisms, but they are configured for opposite functions: one normally closed for safety, one normally open for control. Always specify by function to avoid mixing them up.