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Author Topic: dot tubing and fittings  (Read 2892 times)
thomasinnv
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« on: November 06, 2010, 08:08:06 PM »

Most of the suspension air lines have been replaced with dot tubing and compression fittings, but there are still a few oem lines in place that I would like to replace, and hopefully eliminate some slow leaks in the process.

So, who would be a good supplier for 1/8" dot tubing and associated fittings?  I prefer to be able to order it online and just have it shipped to me.  There's really not anywhere near me that I can get anything that I am aware of.  I am in Bouse AZ.
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« Reply #1 on: November 06, 2010, 08:15:06 PM »

I've used both of these guys for various fittings and lines with good luck:

http://www.hoseandfittings.com/

http://www.ryderfleetproducts.com

Steve
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« Reply #2 on: November 07, 2010, 06:23:26 AM »

You are not suggesting replacing exzisting rubber air line with plastic are you?

If there is any movement at all that needs to take place between the ends it must remain rubber.
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thomasinnv
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« Reply #3 on: November 07, 2010, 07:56:45 AM »

You are not suggesting replacing exzisting rubber air line with plastic are you?

If there is any movement at all that needs to take place between the ends it must remain rubber.

I'm not doing anything with any of the brake lines, just the airbag lines.  Most of the hard lines have been replaced already but there are a few left here and there that I am going to replace, such as between the front leveling valve and the tee between the left and right side bags, and the line feeding the valve.  I found a couple of leaks at the adapter fittings and it just makes more sense to me to replace the hard lines with dot plastic rather than mess with trying to get them to stop leaking.  The dot plastic also makes for an easy roadside repair if the need arises.  (you never know when you might have collateral damage from road shrapnel or a blow out)
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« Reply #4 on: November 07, 2010, 10:17:47 AM »

NAPA will have or can get what you need.
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thomasinnv
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« Reply #5 on: November 07, 2010, 05:06:49 PM »

I found the adapters/fittings on Grainger's website for around a buck a piece.  I ordered a hand full along with some extra sleeves.  I also ordered 50' of tubing, but not from grainger, they were really high.
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« Reply #6 on: November 07, 2010, 05:11:56 PM »

I found the adapters/fittings on Grainger's website for around a buck a piece.  I ordered a hand full along with some extra sleeves.  I also ordered 50' of tubing, but not from grainger, they were really high.

Are you sure they have the DOT stamp for that price?
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Brian Elfert - 1995 Dina Viaggio 1000 Series 60/B500 - 75% done but usable - Minneapolis, MN
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« Reply #7 on: November 07, 2010, 05:17:28 PM »

Only the push in type fitting are DOT stamped 
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« Reply #8 on: November 07, 2010, 05:34:37 PM »

Only the push in type fitting are DOT stamped 

When I worked at a Fluid Power house, we sold Parker and Dayco-Eastman brass DOT compression fittings that were stamped D.O.T. on the cap. That was several years ago so maybe it has changed now. Most people also used an insert inside the nylon tubing along with the sleeve. 
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kyle4501
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« Reply #9 on: November 07, 2010, 05:52:54 PM »

If you are trying to avoid leaks, the push-in fittings should be avoided.
We use them on the machinery we build because it saves time in assembly - NOT because they are a superior product.
Push-in fittings depend on an O-ring to seal against the tube. Due to the design of the o-ring gland, when the o-ring dries out & cracks, it will separate & allow air to escape.
Also, If the tube end has a sharp edge, it can scratch the o-ring when the tube is pushed in. I've seen plenty that seals OK at first, but leaked horribly after a short time.

When we want a superior product, we use a fitting with a ferrule & nut. Takes longer, but no leaks (if you install them properly).

I've found a good selection of fittings at a small truck parts store. The Parker brass fittings I last bought have DOT stamped on the nut.
I haven't used any push-in fittings . . . . for the reasons I just mentioned.
YMMV

Good luck!
Kyle
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« Reply #10 on: November 07, 2010, 06:20:13 PM »

I just checked a bag of 1/4 in fitting I bought from Ryder Fleet no DOT stamp on those I did notice a stamp on the fittings for the brake pods but it ii s for rubber.FWIW I did find out hose places are not allowed to sell a compression union for the DOT lines now.


good luck
« Last Edit: November 07, 2010, 06:30:14 PM by luvrbus » Logged

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« Reply #11 on: November 07, 2010, 07:23:22 PM »

I bought an ordinary brass compression fitting at the hardware store for the connection to my air ride seat.  I had the seat out this summer and it leaked pretty bad when assembled.  It turned out to be missing the insert inside the tubing, but I didn't realize that until after I bought another fitting from C&J Bus Repair.  I didn't check if the new fitting was DOT approved as I figured that C&J would sell me the right thing.
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« Reply #12 on: November 07, 2010, 07:56:46 PM »

I agree that compression is far superior to Push-To-Connect fittings as long as the installer doesn't over OR under tighten them. The only Push-To-Connect fittings I would use would be the Legris Brand and then it would only be used with Poly tubing and not Nylon tubing. Only trouble is I am not sure if Legris (French Company) even makes DOT fittings and the Poly tubing has a much lower PSI rating than Nylon.
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thomasinnv
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« Reply #13 on: November 07, 2010, 08:07:26 PM »

they are not a push in type, they are the compression type with the insert.  The product description says this: "For Use With SAE J844 Type A or B nylon tubing, Standards Exceeds DOT Pressure Requirements for air brake systems."  I would not use the simple push in type connectors, I have always been leary of them.  I just don't trust them.
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« Reply #14 on: November 07, 2010, 08:33:28 PM »

they are not a push in type, they are the compression type with the insert.  The product description says this: "For Use With SAE J844 Type A or B nylon tubing, Standards Exceeds DOT Pressure Requirements for air brake systems."  I would not use the simple push in type connectors, I have always been leary of them.  I just don't trust them.

Both the "A" & "B" nylon tubing is Air Brake tubing and is DOT Approved. The "B" nylon is a re-enforced tubing and usually does NOT require inserts since the wall thickness is thicker. I think most people just use the "A" tubing with inserts since it works just as well and is a little cheaper.
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luvrbus
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« Reply #15 on: November 08, 2010, 04:50:15 AM »

You guys are funny no push in type fitting then you think the Shark Bite fitting are the best thing in world  lol



good luck
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« Reply #16 on: November 08, 2010, 05:36:20 AM »

It does seem a bit incongruous, but a water line blowing off is a whole lot different than a brake line blowing off.
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« Reply #17 on: November 08, 2010, 06:29:23 AM »

I've never liked the shark bite fittings either - seems the only thing the shark bit was my butt . . . .  Tongue
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« Reply #18 on: November 08, 2010, 07:13:24 AM »

I think it's interesting that we have this tendency to reject modern technical solutions for things like air lines in favor of old, outmoded ways of doing things.  Modern is almost always cheaper, except sometimes when it's regulatory upgrades in methods and practices, and while cheaper is often better, but we take a long time to trust it.

I don't  know anything about modern air lines but like many here it would be a hard leap of faith for me to put modern "plastic" air lines in place of good old fashioned rubber and braid lines, or steel/copper hard lines, even though logically I know the new ways are indeed better.  When was the last time you saw a copper line with a fatigue crack, or a corroded steel line, vs the same on a plastic line?

Brian
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« Reply #19 on: November 08, 2010, 07:32:12 AM »

When/if we get a modern constructed coach out to 50 years old, it will be interesting to see what systems made it from the start, and which were replaced. Lots of stock copper lines in the 4104 fleet still going strong.

The abuse of time is hard to replicate in the lab.

And increasingly, the heavy vehicle manufacturer is only focused on the first owner being satisfied, and the second owner being able to repair it for awhile. Much the same as our automobiles for some decades now.

I prefer to put connections together by way of threaded means, leaving the seal snug inside to do one job.

No doubt the time will come when those that follow will giggle, but by then, the materials will have advanced again, making the comparisons hardly fair.

March on technology!

And do it your way!

happy coaching!
buswarrior



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thomasinnv
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« Reply #20 on: November 08, 2010, 08:26:27 AM »

You guys are funny no push in type fitting then you think the Shark Bite fitting are the best thing in world  lol



good luck

I ran all my water lines in pex tubing, but I used all brass fittings with crimp rings.  I just felt more confident in them than the shark bite stuff.


I don't  know anything about modern air lines but like many here it would be a hard leap of faith for me to put modern "plastic" air lines in place of good old fashioned rubber and braid lines, or steel/copper hard lines, even though logically I know the new ways are indeed better.  When was the last time you saw a copper line with a fatigue crack, or a corroded steel line, vs the same on a plastic line?

Brian

A couple of the hard lines I will be replacing have fatigue cracks right close to the fitting.  My choices are to either replace the entire hard line that is broken, requiring me to make appropriate bends and get the length just right.  Or option B which I have chosen is to just use dot plastic in it's place.  Option B seems much easier and needs to be less precise.  If I were working on brake lines, which I'm not, I might reconsider my strategy.
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There are three kinds of people in this world....those that make things happen, those that watch things happen, and those that just wonder what the heck is happening. Which one are you?

1977 MCI Crusader MC-8
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95% converted (they're never really done, are they?)
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