Pneumatic Tubing

FIRST General Forum
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Are you allowed to use stainless steel tubing over the regular plastic tubing for pneumatics in the robot?

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My team is also curious about this, but there is also always the concern of added weight to the robot?

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I don’t read anything in R801-R814 that would specifically prohibit stainless steel tubing, assuming it’s properly rated for pressure and doesn’t exceed the maximum tubing OD specs.

That said, I am curious what the reason is that you’d want to go with what is almost certainly heavier and harder to work with.

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It isn’t necessarily heavier, it is a thinner wall to allow a faster flow rate for the 60 psi. puncher.

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I seriously doubt that this is going to help you get what you’re after. It’s not really the tubing that’s going to limit your flow rate, it’s the solenoid. And that is something that very much is limited by rule R804 C.

solenoid valves with a maximum â…› in. (nominal, ~3 mm) NPT, BSPP, or BSPT port
diameter or integrated quick connect ÂĽ in. (nominal, ~6mm) outside diameter tubing
connection
The maximum allowed port diameter ensures that you won’t get any flow rate boost by using a larger ID tube. And, before someone suggests it, remember that you can’t hook more than one solenoid output to a given pneumatic circuit, per R814.

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Some legal techniques that can speed up pneumatic actuation:

  • Put the valve as close as possible to the cylinder (e.g. minimal length tubing run)
  • Put a low pressure storage tank as close as possible to the valve (e.g. minimal length tubing run to stored air)
  • Use multiple smaller bore cylinders rather than one large bore, and use a valve per cylinder (while it’s not legal to plumb multiple valves into a single cylinder, it’s perfectly legal to have multiple cylinders with one valve per cylinder)
  • Use a latch release mechanism (precharge the cylinder, then release it)
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Spectrum Robotics 3847 has a pretty terrific Pneumatics guide that addresses this very issue:

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I don’t understand the question. Can you describe better, what you want to do?

It sounds to me like you want to insert the plastic tubing inside a piece of metal tubing. This sounds legal to me. If that is not your intent, if you intend to replace part of the plastic tubing run with metal tubing, then you probably need to make sure the metal tubing meets the rules for Pneumatic Components.

But I’d still like to understand what you want to do.

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