Air bag fitting ?

[LooseCannon]

I understand the "white stuff" on the NPT threads to be an anti-galling lubricant.

[XXL]

Originally Posted by Shane

Don't take my word for it, do some research for yourself.

1. ask for information
2. disagree with information received
3. when prompted to do own research, state "don't have time"
4. ????
5. Profit!!!

This is a great place.

[Shane]

It is a great place Ken ... most times.

[cajundragger]

they were.

[Shane]

FWIW: D.O.T. fittings are rating to the same pressures regardless of whether they are polymer or metal.

[cajundragger]

well from what I understand DOT takes the average burst pressure and divides it by 3 to give the psi rating.

[Shane]

Originally Posted by cajundragger

well from what I understand DOT takes the average burst pressure and divides it by 3 to give the psi rating.

That is correct cajun. It's called a safety margin. If I recall correctly from my PH test days (seems another lifetime ago now) most D.O.T. fittings are rated at a 3X safety margin, and some even being 5X safety margin. Meaning, to obtain a 3X safety margin rating and it is D.O.T. rated for 150 PSI then it has been tested to safely carry 450 PSI. 5X safety rating would be tested to 750 PSI.

Remember, the smaller the orifice, the larger the pressure required to rupture. In other words, it takes much more pressure to rupture a 1/8" fitting than it does a 1/2" fitting. Thus the reason for higher safety margins on smaller orifice fittings.

[cajundragger]

Originally Posted by Shane

That is correct cajun. It's called a safety margin. If I recall correctly from my PH test days (seems another lifetime ago now) most D.O.T. fittings are rated at a 3X safety margin, and some even being 5X safety margin. Meaning, to obtain a 3X safety margin rating and it is D.O.T. rated for 150 PSI then it has been tested to safely carry 450 PSI. 5X safety rating would be tested to 750 PSI.

Remember, the smaller the orifice, the larger the pressure required to rupture. In other words, it takes much more pressure to rupture a 1/8" fitting than it does a 1/2" fitting. Thus the reason for higher safety margins on smaller orifice fittings.

thats what I thought.


I know for a fact air tanks are 3x. which is why I have no problem with running 200psi in a 150 psi tank.

[Liz]

N2TRUX is unavailable this week.. so ya'll are stuck with fill in staff I shall say this once only. Don't turn threads into pissing matches. Its fine to disagree, debate etc.. Once it degenerates into a bs fest, it will result in the post being closed and infractions and or suspensions being issued.

Shanes post was reported in this thread for the use of the word kiddo.. ya'll need to grow up. He was spoken down to and did the same in return, get over it.. move on.

Sorry to **** in the OPs post. N2TRUX posted recently about the bs stopping. Please ensure it does. If you dislike a post, report it. If you feel compelled to reply back and keep the bs going, its not going to work out well for yourself in the end.

thanks!

[robin58]

Learn something new every day. I always thought white teflon was for liquid plumbing use and yellow teflon (e.g. http://www.imacsystems.com/Gas_Seal_...hread_Tape.pdf) tape for gas/air type environments. But if I understand some comments correctly then one should use a sealant like the referenced Loctite?

[LooseCannon]

Originally Posted by robin58

Learn something new every day. I always thought white teflon was for liquid plumbing use and yellow teflon (e.g. http://www.imacsystems.com/Gas_Seal_...hread_Tape.pdf) tape for gas/air type environments. But if I understand some comments correctly then one should use a sealant like the referenced Loctite?

From research I found that most recommend Loctite 545 as a NPT fitting thread sealant.

[IMG]http://www.*****************/files/imagecache/product/Loctite_545_Thread_Sealant_0.jpg[/IMG]

[fixit-p]

Originally Posted by robin58

Learn something new every day. I always thought white teflon was for liquid plumbing use and yellow teflon (e.g. http://www.imacsystems.com/Gas_Seal_...hread_Tape.pdf) tape for gas/air type environments. But if I understand some comments correctly then one should use a sealant like the referenced Loctite?

Anymore thats all I use teflon tape for is household plumbing. The 545 is good stuff but also Slic-Tite® PTFE (pipe dope) sealant is good (rated 300 psi gas) it's basically a teflon paste. With most of the components I use (hydraulic and pneumatic) the use of teflon tape will void the manufactures warranty... it has a tendancy to shread.

[Shane]

Safety margins are also sometimes referred to as a Safety Factor ... such as a 3:1 Safety Factor for DOT fittings.

I forgot that in my last post.

[XXL]

May also want to check the ASME BPV for their certification requirements.

[fixit-p]

Safety factors are established by the hose and fitting manufactures and for the most part they are usually consistent with each other. DOT ratings aren't based on safety factors example the minimum bursting pressure for 1/2" nylon hose to be DOT approved is 900 PSI so a 1/2" hose rated at 300 psi w/3:1 safety factor meets the pressure requirements (there is so much more crap involved) Which brings us to the end fittings they must hold at the minimum burst pressure rating in this case 900 psi (pressure tested w/ water absent of air at a rate of 3000 psi per minute) that's 900 psi in 18 seconds doesn't matter if it's brass ptc, nylon ptc or compression. I'll bet if you check your DOT approved nylon hose you won't find any pressure ratings printed on the hose it's self.

[justpball]

aaarrrrggggg, my brain is swelling...to much information....LOL
Thanks for all the info guys. I love all the different guys on here, I think I could pretty much ask any question and get it answered.