Legal Pneumatic Fittings - Nipples & Elbows?

[nuclearnerd]

R77 of the 2014 game manual states "Pressure transducers, pressure gauges, flow control valves, and connecting fittings" are legal. Can I assume that means any connecting fittings (which are rated for the pressure)?

We're looking to use 1/4" nipples and elbows to connect a tank to a nearby (stationary) cylinder, rather than 0.16" ID tubing for better flow rate. It looks legal to me, (especially as many teams use manifolds and cylinders with 1/4" npt ports).

[jmartin]

Also according to R77 (e), any tubing used has to have an ID of 0.16". So I don't think using 1/4" NPT would be any more useful since you're still limited by the tubing.

Are you sure it isn't ports with 1/4" OD that you're thinking of? Because the 1/8" NPT ports we have fit 1/4" OD tubing. The 1/8" NPT ports have an ID of 1/8". It can be a bit confusing that the 1/8" NPT ports have labels on them saying 1/4.

[theawesome1730]

We've done it in the past with no issue. You can always set it up with the fittings you want and fix it if it is not legal provided it is something you design to be easily changeable

[nuclearnerd]

Originally Posted by jmartin

Also according to R77 (e), any tubing used has to have an ID of 0.16". So I don't think using 1/4" NPT would be any more useful since you're still limited by the tubing.

Are you sure it isn't ports with 1/4" OD that you're thinking of? Because the 1/8" NPT ports we have fit 1/4" OD tubing. The 1/8" NPT ports have an ID of 1/8". It can be a bit confusing that the 1/8" NPT ports have labels on them saying 1/4.

That's just it. Elbows and nipples are *not* tubing, so I am thinking that rule doesn't apply. We are planning to use 1/4" (nominal ID) pipe nipple to go into a 1/4" NPT port.

[jmartin]

I see. I would be careful though, perhaps someone should ask about this on the q&a.

[Al Skierkiewicz]

Guys,
Can we agree that "we used it in the past" is not a response.
Thanks.

[martin417]

There are very few restrictions on the use of "fittings", just be careful in defining a fitting. For example;

A quick exhaust valve is not a fitting, Nor is a check valve, but a 1/4" NPT close nipple is.

Also keep in mind that the 1/8" NPT restriction is for valves, not fittings. It is allowable to use fittings larger than 1/8" NPT, just not valves that have ports larger than 1/8" NPT.

[FrankJ]

The question is do you consider a nipple a fitting or a tube. I would tend to consider a close (short) nipple a fitting (legal). At some point it would transition into a pipe, which it really is, which be closer to tubing (not legal)

Keep in mind I am not the one inspecting your robot.

[nuclearnerd]

Thanks for the input. I'm glad to get some backing on my interpretation.

Personally I'm not worried about a "pipe" being mistaken for "tubing". In this area, "tubing" usually means flexible (or at least, bendable). I'm guessing the rule is there to minimize damage if the vulnerable plastic tubing is cut or disengaged, which isn't a risk with hard pipe. I agree the question is probably worth a Q&A (I don't know how to do that though - I'm a first year mentor).

[FrankJ]

Personally I'm not worried about a "pipe" being mistaken for "tubing".

In that case "pipe" is not a fitting & not on the list of approved items. You probably OK with short nipples, without a Q&A only your inspector knows for sure.

[Al Skierkiewicz]

The rule was simplified this year as 0.160 ID tubing has the same flow restrictions as saying Cv of 0.32 or about the same flow as 1/8" NPT port diameter.

[lcoreyl]

Originally Posted by Al Skierkiewicz

The rule was simplified this year as 0.160 ID tubing has the same flow restrictions as saying Cv of 0.32 or about the same flow as 1/8" NPT port diameter.

If 1/8" NPT port diameter has a Cv of 0.32, then why would a solenoid with 1/8" NPT output advertise a Cv of 0.75? (mcmaster 6124K511)

[fsgond]

Originally Posted by Al Skierkiewicz

Guys,
Can we agree that "we used it in the past" is not a response.
Thanks.

But Al, I have used that response in the past

[DonRotolo]

Originally Posted by fsgond

But Al, I have used that response in the past

Best. Response. Ever.

[Al Skierkiewicz]

Why do you guys to this to me?