Pre-charging pneumatic air tank

[magnets]

I think that some of the rules for the pneumatics are a little weird. All the "incidents" mentioned have not been due to over pressurization. The relief valve takes care of that.

I don't get why they think that the cRIO control is going to be a super safe solution. They're relying on programming and wiring done by inexperienced high school kids.

This question is for inspectors. Which of the following would be illegal?

-Connecting the compressor to a drill battery
-Connecting the compressor to a robot battery with breaker
-Programming the robot to run the compressor an additional 10 seconds after the pressure switch says its full to fill all the way to 125 psi because the pressure switch stops at 115 psi.
-Programming the robot in auto to run the compressor non stop and let excess pressure vent through the relief valve
-Having a button on the computer that runs the compressor when held, used to charge a system at 95 psi to 115 psi before a match starts
-Having a button on the computer that runs the compressor when held, used to charge the system until the relief valve starts releasing air

-shorting out the pressure switch to run compressor

[Jon Stratis]

Originally Posted by magnets

I think that some of the rules for the pneumatics are a little weird. All the "incidents" mentioned have not been due to over pressurization. The relief valve takes care of that.

Do you have any idea how many relief valves I've had to help teams set at competition? The above setups would not have had that protection in their shops at home, as most often these relief valves come from the factory set well above 150 psi.

-Connecting the compressor to a drill battery No
-Connecting the compressor to a robot battery with breaker No
-Programming the robot to run the compressor an additional 10 seconds after the pressure switch says its full to fill all the way to 125 psi because the pressure switch stops at 115 psi.No
-Programming the robot in auto to run the compressor non stop and let excess pressure vent through the relief valveNo
-Having a button on the computer that runs the compressor when held, used to charge a system at 95 psi to 115 psi before a match startsNo
-Having a button on the computer that runs the compressor when held, used to charge the system until the relief valve starts releasing airNo

-shorting out the pressure switch to run compressorNo

The rules are pretty clear...

[Tristan Lall]

Originally Posted by magnets

This question is for inspectors. Which of the following would be illegal?

I think it's important to specify the situation. Teams cannot be expected to maintain their robot in a perpetual state of rules compliance (for example, during maintenance, robots often are in no state to pass inspection or play). Instead, they must demonstrate compliance at inspection and during gameplay. There is a different set of rules (and guidelines) that are in effect throughout an event, largely due to safety considerations.

[DonRotolo]

I'm sorry folks, but which part of "One and only one" is not perfectly clear to you?

Aside from the other reasons mentioned, having two compressors gives a team an unfair advantage, since the on-board compressor is not being run as much. This keeps it cooler, allowing it to be more efficient and effective.

Seriously: Follow the rules or don't, but if you don't, stop trying to rationalize your cheating.

[orangemoore]

Originally Posted by DonRotolo

I'm sorry folks, but which part of "One and only one" is not perfectly clear to you?

Aside from the other reasons mentioned, having two compressors gives a team an unfair advantage, since the on-board compressor is not being run as much. This keeps it cooler, allowing it to be more efficient and effective.

Seriously: Follow the rules or don't, but if you don't, stop trying to rationalize your cheating.

This.
Seriously this conversation should be over. What else is there to talk about?

[pfreivald]

Originally Posted by orangemoore

This.
Seriously this conversation should be over. What else is there to talk about?

Yes, it should.

But we should talk more about this:

Originally Posted by magnets

I think that some of the rules for the pneumatics are a little weird. All the "incidents" mentioned have not been due to over pressurization. The relief valve takes care of that.

First, the relief valve must be properly installed in order to do its job.

Second, relief valves bleed, they don't gush--it's entirely possible to overpressurize a system by adding air faster than the relief valve can relieve it.

Third, I'm 100% positive that you don't have personal knowledge of all the "incidents" mentioned, and so cannot speak authoritatively on what did or did not cause them.

Fourth, rationalizing unsafe or disallowed practices with shoddy handwavium arguments and invented "facts" is not useful. So please stop.

[EricH]

Originally Posted by pfreivald

First, the relief valve must be properly installed in order to do its job.

Which includes calibration. The one and only time I'd actually recommend shorting the pressure sensor is to calibrate the relief valve--and I can think of a way to test that without even involving the sensor. The idea, of course, is to run the relief valve up to about 130 psi and see if it vents before then (if not, immediately vent the system using a dump valve and readajust).

[magnets]

Originally Posted by pfreivald

First, the relief valve must be properly installed in order to do its job.

Second, relief valves bleed, they don't gush--it's entirely possible to overpressurize a system by adding air faster than the relief valve can relieve it.

Third, I'm 100% positive that you don't have personal knowledge of all the "incidents" mentioned, and so cannot speak authoritatively on what did or did not cause them.

Fourth, rationalizing unsafe or disallowed practices with shoddy handwavium arguments and invented "facts" is not useful. So please stop.

1). Yes, it does require that my relief valve is connected and calibrated. But I've already done that so that I can pass inspection.

2). Please show me an FRC compressor filling faster than the relief valve can bleed.

3). The two incidents mentioned in this thread were at normal operating pressure. Please find me the one that isn't.

4). Please show me the rule that prevents me from running the compressor for an extra couple of seconds after the pressure switch tells the compressor to stop. Also, can you show me my "fact" I invented?

[Jon Stratis]

Originally Posted by magnets

4). Please show me the rule that prevents me from running the compressor for an extra couple of seconds after the pressure switch tells the compressor to stop. Also, can you show me my "fact" I invented?

I would argue R88 part C prevents that. Since you are choosing to continue running the compressor after the switch tells you to stop, I would say you are over pressuring the system - you're pressuring it past the stop point for the switch, which is the only legal feedback for controlling the compressor.

R88
The pressure switch requirements are:

It must be connected to the high-pressure side of the pneumatic circuit (i.e. prior to the pressure regulator) to sense the “stored” pressure of the circuit.
The two wires from the pressure switch must be connected directly to a digital input and ground pin on the Digital Sidecar.
The cRIO must be programmed to sense the state of the switch and operate the relay module that powers the compressor to prevent over-pressuring the system.

[magnets]

Originally Posted by Jon Stratis

I would argue R88 part C prevents that. Since you are choosing to continue running the compressor after the switch tells you to stop, I would say you are over pressuring the system - you're pressuring it past the stop point for the switch, which is the only legal feedback for controlling the compressor.

R81 “Stored” air pressure on the ROBOT must be no greater than 120 psi.

My pressure switch stops at 114 psi. So, if I run for 8 extra seconds, I'll get to 119. It's not over the pressure limit.

[cgmv123]

Originally Posted by magnets

R81 “Stored” air pressure on the ROBOT must be no greater than 120 psi.

My pressure switch stops at 114 psi. So, if I run for 8 extra seconds, I'll get to 119. It's not over the pressure limit.

There is a way to calibrate your pressure switch to stop at 120psi.

[magnets]

Originally Posted by cgmv123

There is a way to calibrate your pressure switch to stop at 120psi.

How?

[cgmv123]

Originally Posted by magnets

How?

I don't know, but see this post:

http://www.chiefdelphi.com/forums/sh...77&postcount=5

[FrankJ]

You can recalibrate your pressure switch. Remember you don't have to use a specific pressure switch. You really don't want to stop at 120 psi because with scatter it might be 121 psi the one time the inspector is watching it. Those little pressure gauges aren't that accurate anyway.

With all the exploding air tanks, regardless of reason, expect the inspectors to be particularly diligent and narrow in their interpretation of the rules. To get the sticker you will have to conform to their interpretation, not yours. That is just is how life works.

[cgmv123]

Originally Posted by magnets

4). Please show me the rule that prevents me from running the compressor for an extra couple of seconds after the pressure switch tells the compressor to stop.

R34 does not list compressed air not generated in compliance with pneumatic rules as an allowable source of energy on the robot.

R88 says the cRIO must be able to control the compressor relay based on the state of the pressure switch. Shorting the pressure switch doesn't change its state.