I wanted to make a post here and ask if anyone has ever done any hardline tubing for pneumatics on their robot, and if it was even legal I was unsure after looking at last years game manual and was unable to find anything specifying it wasn’t. If anyone has ever done this please explain how and where you bought the parts from.
See R804, specifically R804-D please.
D. additional pneumatic tubing, with a maximum ¼ in. (nominal, ~6 mm) outside diameter,
R804-D doesn’t specify that the tubing must be flexible, merely that it be no more than 1/4" or 6mm in OUTSIDE diameter.
I do recall a Q&A from 2017 (STEAMworks). A team wanted to use brass or copper tubing to get with the season esthetic, and the ruling was that it was not allowed, but R82E in 2017 read:
Additional pneumatic tubing, with a maximum 0.165 in. (nominal) inside diameter, functionally equivalent to that provided in the KOP,
so the rule has changed in substance, as rigid tubing is NOT fuctionally equivalent to the flexible KOP tubing.
That said, if you intend to use hard tubing this year, I recommend:
- Read the 2023 R804-D (or its equivalent in the unlikely event the rule is re-numbered) thoroughly.
- Verify that the tubing is actually rated for the appropriate pneumatic pressure (R802).
- I doubt seriously that hard tubing will work with press fittings. Figure out how you’re going to get these tubes fitted to your other pneumatic devices using only unmodified COTS parts. R803 apparently prohibits installation of compression, flare or crimp fittings, and definitely prohibits cutting your own threads.
- Post a Q&A, preferably the day it opens asking if hard tubing violates R804-D. Then a similar question about your fittings, especially if they permanently deform the tubing.
- Have a backup plan.
From experience installing air ride in vehicles, hard line can work with push connect fittings (copper and steel); that aside I’m not sure where or why someone would want to use metal lines on a robot.
I think part of the reason for that change was that Automation Direct sells compact hard plastic U tubing to connect between their small gauges/regulators. However, I don’t remember if they were available in the KOP or FIRST Choice.
From experience with water systems, confirm, but the push connect fittings are slightly different IIRC. They’re specifically set up for metal.
At work we use 1/4" copper tubing (ice maker water line) with 1/4" SMC push fittings for custom-bent (rigid) air blowoffs (chip clearing, smoke removal, etc.). Not exactly a high-pressure application though.
IMHO, for weight reasons alone I’d personally steer clear of it on an FRC bot. Semi-rigid plastic line, sure if it’s for static plumbing (not being flexed a lot); I’d only use it if there was a compelling reason (a reel of it was donated to the team, etc.).
I spend a fair bit of time plumbing stainless tubing for (much) higher pressure lines on my rocketry team. Beyond the weight issue, you’re also going to spend a considerable amount of effort cutting and bending. Don’t put yourself through that if you don’t have to.
Aluminum versa tubing is easy to bend and easy to work with. Would work well for replacement of urethane or nylon tubing
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