Pressure Switch Not Working?

[anthonygraff24]

We are having some trouble with getting our compressor to work on its own. What we want it to do is to start on its own (it does that), stop when the system hits ~120psi, and restart when it drops back down to ~90psi. Our code looks like this:

if (airCompressor.getPressureSwitchValue()) {
airCompressor.setRelayValue(edu.wpi.first.wpilibj. Relay.Value.kOff);
}
else {
airCompressor.setRelayValue(edu.wpi.first.wpilibj. Relay.Value.kOn);
}

However, the compressor just runs without stopping. Any ideas on why this might happen?

[Team3266Spencer]

The Compressor class provided by WPI should handle everything for you.
Initialize it like this:

new Compressor(int pressureSwitchChannel, int compressorRelayChannel)

and then call the method start() to turn it on. It will automatically turn itself off when the pressure switch switches.

If it's still not working it could be a wring issue or the pressure switch is in the wrong place. Double check there's no short circuits in the wires for your pressure switch. The pressure switch should be located before your 60 psi working air regulator.

http://www.wbrobotics.com/javadoc/ed...ompressor.html

[DonRotolo]

I can't comment on your code, but you can test if the switch closes at ~90 PSI and opens at ~120 with an ohmmeter.

Then verify (using code) that the DIO port is 'seeing' the switch change properly.

If it is, then make a program to command the compressor relay on and off, and see if you can get that to work. Pay attention to the LEDs at the DSC Relay ports.

If you do these 3 things, good chance you'll find the issue.

[jfitz0807]

We're having a similar problem. R82 states "“Working” air pressure on the ROBOT must be no greater than 60 psi and must be provided through one primary adjustable, relieving, pressure regulator." It recommends the Norgren R07-100-RNEA. Our Norgren R07-100-RNEA regulator "bleeds" at 60psi. If the regulator bleeds to relieve pressure at 60psi, how can we possibly get more than 60psi upstream?

[cgmv123]

Originally Posted by jfitz0807

Our Norgren R07-100-RNEA regulator "bleeds" at 60psi. If the regulator bleeds to relieve pressure at 60psi, how can we possibly get more than 60psi upstream?

The intent of a regulator is that downstream pressure isn't more than 60psi, ever. The pressure switch should be located on the "high pressure" side of the robot.

[Mr V]

Originally Posted by jfitz0807

We're having a similar problem. R82 states "“Working” air pressure on the ROBOT must be no greater than 60 psi and must be provided through one primary adjustable, relieving, pressure regulator." It recommends the Norgren R07-100-RNEA. Our Norgren R07-100-RNEA regulator "bleeds" at 60psi. If the regulator bleeds to relieve pressure at 60psi, how can we possibly get more than 60psi upstream?

It is bleeding because you have the high side input connected to one of the output ports. If you look at the bottom of the regulator there will be an arrow showing the direction of the flow. The port that lines up with the non pointy end of the arrow is the input, the other 3 ports are the output and they will bleed off any pressure in excess of the pressure the regulator is set at.

[jfitz0807]

We have that. We can see our high pressure gauge increase along with the gauge on the regulator. The problem is that when the pressure gets to 60psi, the regulator lets air out so the upstream side can't get any more pressure than 60psi.

For testing, we used the adjustable regulator with the yellow ring in place of the Norgren. I know this is illegal according to the rules, but I wanted to prove the concept. Since the yellow regulator doesn't bleed, we were able to get up to 115psi on the high side and 60psi on the low side.

How can you get more than 60psi on the high side if the regulator bleeds at 60psi?

[kevin.li.rit]

Originally Posted by jfitz0807

We have that. We can see our high pressure gauge increase along with the gauge on the regulator. The problem is that when the pressure gets to 60psi, the regulator lets air out so the upstream side can't get any more pressure than 60psi.

For testing, we used the adjustable regulator with the yellow ring in place of the Norgren. I know this is illegal according to the rules, but I wanted to prove the concept. Since the yellow regulator doesn't bleed, we were able to get up to 115psi on the high side and 60psi on the low side.

How can you get more than 60psi on the high side if the regulator bleeds at 60psi?

As previously stated, it sounds like you have your regulator plumbed incorrectly. Are you 100% certain it is plugged in the right direction?

[Jon Stratis]

Originally Posted by jfitz0807

We have that. We can see our high pressure gauge increase along with the gauge on the regulator. The problem is that when the pressure gets to 60psi, the regulator lets air out so the upstream side can't get any more pressure than 60psi.

For testing, we used the adjustable regulator with the yellow ring in place of the Norgren. I know this is illegal according to the rules, but I wanted to prove the concept. Since the yellow regulator doesn't bleed, we were able to get up to 115psi on the high side and 60psi on the low side.

How can you get more than 60psi on the high side if the regulator bleeds at 60psi?

We had a similar issue with the Norgren regulator we got from FIRST Choice this year - We triple checked that it was plumbed correctly but it would bleed regardless of which side we put the high pressure into. We pulled it and replaced it with another we had in our pneumatics box, and that one worked perfect on the first try. I figured we had damaged the first some somehow (overtightened or something).

[jfitz0807]

Got it. It looks like we had it plumbed backwards. What's the emoticon for a sheepish grin?

Thanks for the quick responses!

[kevin.li.rit]

Originally Posted by jfitz0807

Got it. It looks like we had it plumbed backwards. What's the emoticon for a sheepish grin?

Thanks for the quick responses!

heh, I'm pretty sure everyone on this thread who said it was plumbed backwards also learned the hard way. See you at the competition.