Operational Testing: Relief Valve, Pressure Switch, and Leaks

Test 1: Pressure Switch / Compressor Shutoff

After plumbing and wiring, confirm the compressor stops at the right pressure. With the vent plug closed, power the robot, connect the Driver Station, and enable — the compressor should run automatically. Watch the stored-pressure gauge: it should shut off around 110-120 psi. The Manual is emphatic: if pressure ever exceeds 125 psi, disable or power off the robot immediately. If pressure stops climbing before shutoff (well below 110 psi), you have a significant leak — fix it before continuing.

Test 2: Validate the Relief Valve

The relief valve is your mechanical last line of defense. To test a factory-set valve: let the system build until the compressor shuts off, then jumper across the pressure-switch terminals (with alligator clips or a metal tool) so the compressor keeps running. The relief valve should begin venting at ~125 psi; if the system reaches 130 psi, immediately remove the jumper and disable. Many relief valves are loud when they trigger — that is normal. For an adjustable valve, the Manual gives a calibration procedure to dial it to relieve in the 120-125 psi band and lock the locknut.

Test 3: Leak Test

Leaks waste your pre-charged air and can leave you powerless mid-match. Charge to ~110-120 psi, then disable and listen. A good target is less than ~10 psi drop over 30 minutes — that lets a robot charged in the queue keep most of its air by match start.

Finding leaks:

• Large leaks: listen for hissing and feel with a wet finger. Common causes: a relieving regulator installed backwards, a mis-plumbed valve/manifold, a missing plug, a tube not fully inserted, or a loose threaded fitting.
• Small leaks: brush a bubble solution (leak-detector fluid or ~4:1 water-to-dish-soap) on each joint and watch for bubbles. Cover electronics and gearboxes first. Common causes: threads with poor/no PTFE sealing, slightly loose threads, or tubing cut off-square or under tension.
• Test both cylinder states: actuate each cylinder to its other position and re-test, so you check the seals on both sides.

Make Testing Routine

Run these three tests after every major plumbing change and again before each event. A system that shuts off correctly, relieves at 125 psi, and holds pressure for 30 minutes is safe, legal, and competition-ready.