Setting the Pressure Relief Valve

Technical Pneumatics
1

I want to make sure we are setting the pressure relief valve correctly.

We are pumping up the system, then adjusting the valve so that it will hold pressure at 125psi.

In other words, we’re not trying to adjust it so that the pressure never goes above 125psi even with the pump running.

This means that the maximum pressure in the system is a bit higher than 125psi. I can’t remember exactly, but the needle on the high side might bounce up to 140 at times when the pump is on. Then when the pump stops the pressure relief valve will continue to vent until the pressure comes down to 125psi.

Does this sound right?

2

:slight_smile: The pressure relief valve is a safety device that has working limits .They are not designed to act as a pressure regulator. If that valve releases during a competition, you risk red cards and DQ. 125 psi is your max limit, and the regulator to operate the system must be set to 60 psi. Higher pressure translates into more volume and force, which is outside the rules. Add accumulator(s) to increase capacity.:slight_smile: :slight_smile:

3

Tech, that is a little misleading. If the valve releases during match play there is no penalty.
To correctly calibrate the valve, jumper the pressure switch so that the compressor runs continuously. Loosen the locking nut on the relief valve and when the pressure reaches at least 125 psi, start to rotate the hexagonal cap until escaping air is heard. Finger tighten the locking nut and repeat. If the valve releases pressure between 125 psi and 130 psi, tighten the locking nut and check one more time. The valves are not precise and not accurate for repeatability. The expectation is if the compressor should lose pressure control and run continuous, nothing on the robot will fail due to high system storage pressure.
**All teams need to make this calibration before using pneumatics as the relief valve is not supplied pre calibrated for 125 psi. **

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