FRC Pneumatic System Diagram

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?


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)

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.


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)


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.


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:

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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.

Hi - What CAD programs do you recommend for pneumatics design? Preferably free.

The real question here is why are you CADing pneumatics? If it’s to layout your system, you’re probably better off just using a pen and paper or CAD (cardboard aided design), rather than spending time making everything in the computer. You can’t legally use custom pneumatic devices and there are a number of places to get CAD models from, so there’s no real reason to have to design your own components. So what are you trying to get out of a CAD program for pneumatics design?

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As a rookie team, they used pen/paper and cardboard modeling last year with graphic drawing for the pneumatic “schematic” last year. This year, we are looking to step up the level of the team. What do you use for electrical?

We generally use pen/paper and cardboard to layout our electrical and pneumatic systems. There’s really no reason to make it more complicated than that.

CADing the mechanics is definitely important. Leaving space for electronics and pneumatics is important and if adding them into your CAD model helps, then great. But there’s really no reason to model the systems independently of the robot. That’s just adding work for no real gain.

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While I agree that your 3D CAD model is not the best tool for making a schematic or even a layout of the pneumatic or electrical systems, I do think there is great value in including the major components in the CAD model.

For one thing, they take up space and despite the best efforts of saying “leave this spot empty” the space for the electronics really needs to be reserved in order to make sure that you will have access. In addition, if you do the layout well, you can CAD the bolt holes in the electronics tray for the components and have those cut when you make that tray. Plus, if you add lightening cutouts in your tray, you can make sure you still have some material to bolt your components to.

Modelling pneumatic cylinders is also a good idea. These components need to have the attachments considered as well as the extended, retracted positions. You want to be able to make sure they have clearance to other components and that you have adequately thought through how the components are going to move. Finally, you want to make sure that the cylinders are adequately protected and not exposed to bending of the rods due to hard hits with the field elements or other robots.

Wiring and tubing is hard to model. But if you don’t think about where those wires and tubes are going to be routed, you will end up with a spaghetti of wires and tubes running through your robot. You can really optimize the layout of the electronics and pneumatic systems if you think about where the wires need to run. We have had the cleanest layouts when we start to position the electronics components in the directions closest to the elements they are interfacing with (i.e. locating motor controllers in the direction of the motors they are controlling) so that you do not have a lot of criss-crossing wires running around your robot.

We have not been very successful with that on our team and by the end of the build, we generally have a pretty messy “pit” in the middle of the bot. We have been trying to get better every year and I would say that we are getting better, but we have found that in order to account for this stuff, we really need to start including these in the CAD model at some level.