Pressure Reducing Valve and Sequence Valve: Zoned Pressure Control in a Pneumatic Circuit

One supply line arrives at a single pressure, yet clamping needs high force, pressing needs low force, and one motion must not start until pressure has built up. Pressure reducing valves set the pressure zone by zone; sequence valves queue the motions by pressure. This article explains how the two valves give a single air line a sense of hierarchy.

1. Pressure Reducing Valve: A Set Pressure for Every Branch

A pressure reducing valve drops the higher upstream supply pressure to the stable lower pressure a downstream branch needs. Give each branch that needs a different pressure its own reducing valve and you get zoned pressure control — a main line at 0.6 MPa, the clamping branch reduced to 0.4 MPa, the pressing branch to 0.2 MPa, with no cross-talk between them.

Reducing valves come in direct-acting and pilot-operated versions: direct-acting is simple with moderate accuracy, while pilot-operated holds pressure far more precisely. Selection looks at adjustment range, flow, and regulation accuracy; a version with a built-in gauge makes on-site verification easy.

2. Sequence Valve: Queuing by Pressure

A sequence valve opens only when pressure reaches its set point and then lets air through, producing motion in pressure order. Typical application: the clamping cylinder strokes home first (pressure rises to the set point), the sequence valve opens, and the next cylinder moves — a pressure signal enforces “clamp first, process second” with no electrical control at all.

A sequence valve is essentially a pressure-operated switch. Set it slightly below the stable pressure reached when the preceding motion completes, so it does not trip early.

3. Designing a Multi-Pressure Circuit

One main line, several reducing-valve branches, and the necessary sequence valves are all it takes to build a circuit with multiple pressures and a defined order. Start by drawing a “pressure hierarchy”: which branches share a pressure, which need their own, which motions depend on each other — then add valves layer by layer, and the circuit stays clear.

Field Notes: Three Lessons from the Line

1. One reducing valve serving several different pressure requirements — you end up with a compromise pressure and nothing works properly. Give each pressure zone its own valve.
2. Sequence valve set too close to the working pressure — the slightest upstream fluctuation trips it. Leave margin in the set point.
3. Reducing valve without a gauge — adjustment becomes guesswork and gets repeated on site. Fit a gauge or buy the gauged version.

Conclusion

The reducing valve decides how many pressure levels the line has; the sequence valve decides which motion goes first. Settle the pressure hierarchy and the motion order first, then choose the valves, and one air line will run with both hierarchy and reliability.

Suggested Illustrations

1. Multi-pressure circuit diagram showing zoned pressure control with reducing valves.
2. Sequence circuit diagram for “clamp first, process second”.
3. Structural comparison of direct-acting and pilot-operated reducing valves.

The above content was compiled by the LEANYEE pneumatic technical team from hands-on commissioning experience, for reference by industry peers.

Technical Disclaimer

The fitting selection, thread types, and technical parameters discussed in this article are based on applicable international standards, including ISO 4414 (Pneumatic Fluid Power — General Rules and Safety Requirements), ISO 8573 (compressed air quality), ISO 6358 (flow characteristics), and relevant thread standards such as ISO 7-1, ISO 228-1, and ANSI/ASME B1.20.1, together with publicly available technical information from international manufacturers such as SMC, Festo, and Parker.

This article is intended for general technical reference only. Actual performance may be affected by cylinder bore size, load, operating pressure, temperature, piping layout, and other application-specific factors.

On-site testing and commissioning are recommended where necessary. Always refer to the product documentation and technical parameters confirmed by the manufacturer for the specific product being used.

LEANYEE Technical Team