To save weight, my team decided (okay, mentors sort-of forced this upon us) to mount our air compressor on the cart instead of the robot, charging up its compressed air tanks between matches. I have read the rules regarding the pneumatic system (I know that the external compressor must be powered and controlled by the robot), yet I am still confused about one detail: how exactly do I connect the compressor to the robot’s pneumatic system? We must be able to quickly connect and disconnect the compressor without leaking any pressure. My current idea is to simply screw a pneumatic tube fitting into the free end of the robot’s manual pressure relief valve, and use it to connect to a tube leading to the external compressor (which will have its own manual pressure relief valve as mandated by the rules). Is this legal? Another idea I had was to use a check valve of some sort that wouldn’t have to be manually opened and closed with each filling. Is there any legal pneumatic component resembling a check valve that can be used for this purpose? I know the flow rate regulators used on pneumatic cylinders function somewhat like check valves, but can they be safely and legally used as check valves for this purpose?
The pneumatic tube fitting on the relief valve will work fine. No need to do anything too fancy for this.
We used a similar system with a check valve on the robot and connected a tubing from the off board compressor to the valve and it worked just fine for us.
Thank you Joe G.!
What kind of check valve did you use? I didn’t think there were any FRC-legal check valves (apart from the one-way piston flow rate limiters).
The rules for a detached air compressor are fairly close to those of a compressor on the robot.
What we did is place another vent valve on the detached compressor separate from the fitting/tube used to fill the robot.
This allows you to use your off-board compressor to fill the tanks (connect tube and open robot valve, then close the compressor vent valve), then when you are done you can close the valve on the robot and then vent the pressure in the tube with the second valve. This makes removing the tube significantly easier.
Personally I like our students to just put most of the required components on the off-board compressor anyway since you already need to have the pressure relief valve, and I am saying you should include the manual relief there too. Having a gauge right there is nice to check your pressure quickly.
Also make sure to insulate and clearly mark your electrical connections for the outboard compressor from the robot. These are not standard 12V, but are compressor power (switched by the cRIO). These connectors can sometimes be hard to find on the robot during competition.