FRC Pneumatic System Diagram

Based on 3128 electronic diagram, here’s a diagram for pneumatic that I made for my team.

Let me know if something is missing or if you have any other suggestions.
FRC Pneumatic System Layout.pdf (1002.0 KB)

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Straight away, the relief valve!

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Aren’t you missing the pressure relief valve for the high-pressure section, normally attached to the compressor?

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Off the top of my head, you need gauges on both sides of the main regulator at least (and probably one after the secondary regular too)

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I think they are using the compass symbol to stand in as a gauge. Maybe just adding the label to those to make it easier for people to understand?

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Thanks you’re both right. In fact, I think I’ve never seen a compressor without a relief valve, to me it was part of it.

If the compass symbols are pressure gauges, then I don’t see anything else missing per se.
However, some improvements:

  • Single solenoid valves usually still have two air lines heading to the pneumatic cylinder.
  • I suggest adding in the PCM and wires from it to the compressor, pressure switch, and solenoid valves, and power and CAN lines running off with labels for where to connect them.
  • You should also use or add the official rules name of the Air Release Valve, which is “Pressure Vent Plug”. (usual caveat about rules possibly changing)
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I don’t plan to put any electronic devices on this diagram because I think the one from team 3128 is really complete. Both diagrams are made to work together.

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This is a great diagram. Here are some comments:

I would change your labels of “High Pressure”, “Low Pressure” and “Lower Pressure” to “Storage Pressure”, “Nominal Working Pressure” and “Lower Working Pressure” respectively. This will help make your diagram consistent with the game manual terms and allow students using the diagram to easily correlate they game manual requirements to the components shown in the diagram.

Just for clarity, I would move the regulator to the line between the High Pressure and the Low pressure since that is the device that creates the difference in pressure. Similarly, I would move the secondary regulator to the line between the low pressure and the lower pressure in your diagram.

I would show the pressure gauge for the high pressure as a separate device from the air release valve. Although the diagram in figure 10-14 of the 2019 manual shows these two devices joined together, they are really two separate devices that just happen to be threaded together through a short solid tubing connection. But, more importantly, by showing them as separate devices, it is easier to correlate them to the requirements in the manual and ensure that they are positioned correctly per the game manual rules. For example, the air release valve can be downstream of the regulator as long as it can completely vent all stored air pressure.

There are pressure relief valves that have an integrated air release system (a pull ring on the pressure relief valve that you can pull to manually bleed the system. The McMaster-Carr part number 48435K714 called out in the manual has this feature. If your team plans to use this style pressure relief valve, then it will also serve as the release valve. If you plan to use the older style Norgren pressure relief valves, you will need a separate release valve.

I agree with @GeeTwo that the single solenoids still have two air lines coming out of the solenoid valve. Those single solenoids use a spring to hold the valve in one position and then use the solenoid to the other position, but there are still two positions.

Many teams use manifolds to provide working pressure to multiple solenoid valves. You may want to think about how you would add a manifold to your diagram.

As a general “core” system layout, this diagram is great. Once you actually build a robot and hook up devices (cylinders), you should add them to the diagram. These diagrams are particularly useful if you label your circuits (number or name both the solenoid valve, the cylinders and the tubing for each function) so that you can trace things during your troubleshooting. Also, you would want to correlate the solenoid valves with the wiring on your electronics diagram. Personally, I would like to see the PCM and the wires from the PCM to the solenoids and compressor and limit switch shown in this diagram. That way, you can label the wire numbers to help troubleshoot the system. If a valve is not opening when commanded, it could be that the wires for that channel are not correctly plugged in to the PCM (or have worked lose). This seems like a good reason to have that information on this diagram. I recognize, that would create overlap with your electronics diagram, but maybe the elecronics diagram could stop at the PCM and point you to this diagram for the solenoid valve hookup information.

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Thanks for all your recommandations. Here’s the update version with following changes :

  • Add the relief valve (If you have better ideas for its design, tell me)
  • Add a 2nd air line coming out of the solenoid valve
  • Separate the storage pressure gauge from the pressure vent plug
  • Move pressure regulators to red lines
  • Change pressure gauges design to compass one
  • Rename “air release valve” into “pressure vent plug”
  • Rename high, low and lower pressure labels into game manual terms
  • Rename “limit switch” into “pressure switch”

I still don’t think that it is a good idea to add electronic devices such as the PCM. This diagram is just made to understand how to link pneumatic devices together.


FRC Pneumatic System Layout.pdf (1010.4 KB)

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This looks really good. I agree that the electronics should stay with the electrical diagram. Thanks so much for posting this!

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This makes sense if you are only concerned with building the pneumatic system.

Putting the electrical connections for the solenoids on the pneumatic diagram allows it to show the functionality of the various circuits.

  • This makes it less likely that your programmers activate the wrong circuit so they don’t have to spend time making corrections.
  • When something goes wrong at a competition, it will be faster to troubleshoot.
  • It will be easier to modify your system later.

Hopefully, your team spends more time practicing and competing with your robot than building it.

This probably goes beyond the scope of your diagram, but I will share with you some experience that we have had.

  1. If you follow the FRC Pneumatics Manual, one of the configurations that is shown to arrange the pressure relief valve, gauge, pressure switch, and shutoff valve is on page 19 on the lower half of the page (off board compressor). If you use this arrangement for an on board compressor, the weight of all these components hanging off the compressor will eventually (and in some cases quickly) fatigue the housing of the compressor. So, it is best to not have too many components chained together cantilevered off of the compressor like that. If you do want more than 1 component, I would recommend using a cross fitting so that the weight is not hanging too far out.

  2. Compressor output air can get quite hot, especially if your compressor needs to run a lot during the match. It is not a good idea to use the plastic pneumatic tubing straight out of the compressor. If can get hot which can cause it to loose its strength, swell and eventually pop (and it does make a fairly loud popping sound when it goes). You ant to use some short length of brass pipe connected to the outlet of the compressor to serve as a heat sink and to radiate the heat out so that the tubing does not feel this heat.

These are probably more like best practices than items you would want to include on your diagram. But, if you do re-arrange the items on your diagram, to reflect different FRC legal arrangements, you will want to remember not to fall into either of these traps.

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As of the 2019 rules, this is no longer permissible.

I can confirm this one! In 2014, we thought we’d gotten hold of a bad batch of tubing because it would blow out with a sound like a firecracker, and the air rushing back out through the hole would cool the tube back down.

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Sure. but the configuration of the components shown in that diagram (all chained together) would still be a legal configuration for an on board compressor system (except you would not have the shutoff valve).

I would add the check valve to the compressor graphic.

If you want to learn how to use proper pneumatic symbols, check this out: https://library.automationdirect.com/practical-guide-to-pneumatics/

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Do you think this will be the case going forward, or was it an oddity only for 2019?

Time will tell, but I fully expect that the off-board compressor is gone, at least for a few years.

  • The off-board compressor made inspection a bit more complex, and made it almost impossible to enforce the “no shop air” and “no offboard air storage” rules. (Some teams didn’t even realize it was illegal.) With the current rules, if you see anything pneumatic connected to a robot (excluding pressurizing a wheel), you can be pretty sure there’s a problem.
  • Five pounds also moved from the bumpers to the robot, which allows five more robot pounds which may be used for a compressor (or anything else), and which reduces the use of bumpers as robot structure.
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Hi - What CAD programs do you recommend for pneumatics design? Preferably free.