Somehow we’ve amassed a stupid amount of red pneumatic tubing, and we’re running out black. Do the judges care? In the manual it says that rookies get a bunch of black tubing but “FIRST Choice has an assortment of colors”. Do they care which color goes where in the circuit?
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No, there are no rules around pneumatic tubing color.
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Excellent. Thanks!
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PSA- the kit black tubing has the working pressure printed on it, making it easy for the inspectors to verify that it meets the rules. Some tubing (don’t know about your red tube) does not have any markings on it. We’ve had inspectors ask for data sheets that prove the unmarked tubing meets the rules, so check your tubing and plan ahead accordingly.
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We like to use 1 color for extend and a different color for retract. That way you always know how to reconnect a cylinder if it needs to be replaced or disconnected.
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We prefer clear tubing so we can visually verify that there is pressure.
/s
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We tend to color scheme our tubing both for dividing the extend and retract sides (as @AllenGregoryIV says above) and to match the color scheme of the robot. We’re actually using the KoP tubing this year because our robot’s color scheme is black and yellow, so it fits in perfectly.
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Clear tubing does actually have some benefit; FRC spec pneumatic systems can end up with a concerning amount of condensation, especially in weird loopy runs all too common on more complex robots. Disconnecting a tube out near the bottom of a run has left me with a small puddle a few times over the years.
Maybe that FIRST video that mentions hydraulics has a point
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No rules about it, but having a convention helps when you get in a time crunch. A couple of years, 3946 had four different colors. IIRC:
- Black: Above regulator
- Red: Between regulator and solenoid valves
- Green: Extend
- White: Retract
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Dumb question: how do you know which is extend and retract?
Base it on direction of travel of the piston. Piston out = extend.
i know that. I meant which hole of the piston. Farthest from the shaft or the one right by it?
Positive pressure pushes. The air goes through the “far” hole, pushes on the inside of the piston to extend, allowing air to exit the “near” hole
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Which one is most likely to push the shaft out?
I demoed this a few times; it’s pretty simple if you have a small clean cylinder (shifter size) and aren’t squeamish. Pull the rod half out, and blow in each hole in turn. As noted above, the piston (that is, the plug which slides inside the cylinder and is connected to the rod) moves away from where you apply pressure.
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We just actuate the cylinders and if they don’t move in the correct direction, we disable the driver station, dump the air and swap the tubes. Rinse and repeat until it’s right.
Not particularly elegant, but whatevs.
There are no rules on the color of tubing but I wouldn’t say it doesn’t matter. If you have several devices it may help to color code the tubing by system and in or out just to make tracing problems down easier.
We swap the tubes AND the code, negating the fix. 
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+1 I will want to either be able to read the ratings factory printed on the tubing, or I will want to see data sheets that clearly state the working pressure for the tubing, and that the sheet applies to that specific tubing you are using. I know it can be difficult to verify, but if you have a PO or some type of receipt (BOM) that shows as much as possible that the tubing you are using matches the data sheet, it will save some potential headaches.