The Two-Pressure Circuit: High Side vs Working Side

One Circuit, Two Pressures

The FIRST Pneumatics Manual describes the system as a high-pressure side (up to 120 psi) and a working-pressure side (60 psi or less) , divided by the primary regulator. Air is generated and stored at high pressure for capacity, then stepped down to a gentler working pressure that valves and cylinders actually use. Keeping these straight is the single most important concept in this department.

High-Pressure Side (Storage)

Everything from the compressor up to the inlet of the primary regulator. By rule (R809 in the 2026 manual) the permitted components here are tightly limited:

• Compressor — squeezes air into the system.
• Pressure relief valve — a mechanical safety that vents if pressure exceeds the limit; it must be connected directly to the compressor with hard fittings and is set to release at 125 psi.
• Air storage tank(s) — hold compressed air for the match.
• Pressure switch / transducer — tells the controller when to run or stop the compressor.
• Stored-pressure gauge — shows storage pressure.
• Vent plug (vent valve) — a hand-operated valve to dump all stored air safely.
• Primary regulator — the boundary device that steps high-side storage down to working pressure.

The rules also allow filters and additional pressure sensors/transducers on this side. Solenoid valves and cylinders are not permitted upstream of the regulator.

Working-Pressure Side (Use)

Downstream of the primary regulator, where the action happens. It is more flexible and typically includes:

• Solenoid valves — electrically switch air to move cylinders (single or double).
• Pneumatic actuators — air cylinders or rotary actuators that produce motion.
• Manifolds (optional) — blocks that feed many valves from one supply to reduce plumbing.
• Flow-control / needle valves (optional) — slow a cylinder’s motion.
• Additional regulators (optional) — further reduce pressure for a specific actuator.
• Working-pressure gauge — shows regulated pressure.

Why Split It This Way

Storing at up to 120 psi packs more usable air into your tanks (more actuations per charge), while running cylinders at a capped 60 psi keeps forces predictable and components within their ratings. The regulator is the translator between the two worlds. Internalize this diagram now: as you wire, program, and pass inspection, you will constantly ask ‘which side of the regulator is this part on?’

Key takeaways

• The circuit has a high-pressure storage side (up to 120 psi) and a working side (60 psi max) separated by the primary regulator.
• By R809 the high side allows only compressor, relief valve, tank(s), pressure switch/transducer, gauge, vent plug, regulator, filters, tubing, and fittings.
• The working side holds solenoid valves, cylinders, optional manifolds, flow controls, and extra regulators.
• Storing high and working low maximizes air capacity while keeping cylinder forces safe and predictable.

This lesson was adapted from learnfrc.com.