pic: T Shirt Shooting Robot

[EricH]

Originally Posted by gallo26

A leak warning would be hearing the noise. I'm almost positive that you will hear it, and we have on past tanks. You hear it on robots with pneumatics or anything with leaks. Its the exact same thing if there's a leak in an inner tube or a track ball.

Wait... Let me get this straight. You have never heard a leak in PVC. You have heard it on pneumatics or "anything [air-filled] with leaks". (The edit is because you don't exactly hear a water leak in the same way--or a steam leak.)

Am I correct?

Because if I am, you probably don't know what an air leak in PVC sounds like. It'll likely sound similar, yes... But it won't be the same. You see, an FRC robot's pneumatic system has two types of leaks. One is from a punctured tube, the other is from a poorly sealed valve. A bike tire or trackball sounds about the same as a puncture tube; a poorly-sealed valve will be hard to hear due to the slow nature of the leak. And in fact, I'd rather you had that than a leak in the PVC itself.

What a pneumatic tube, a bike tire, and a trackball have in common is that they are "soft" plastics--thin-walled, flexible, and somewhat "bang-resistant"--that is, they won't make a big mess if they do burst. There are still FIRSTers who can tell you of the doublers in 2004, which, if mistreated, could go all at once on a slight hole. Being flexible, they can bend a bit out of the way. PVC pipe is not nearly as flexible, especially at the size you're using. And if you do develop a leak, you've probably got about 1 shot to realize you do before something happens. You might not hear it, you might not notice a pressure drop, but something's going to give and you hope it isn't catastrophic. That's why we're pushing you guys to switch to a safer material, such as metal--PVC isn't exactly "bang-resistant". (Metal isn't either, but it can sure take more pressure than PVC.)