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DOT compression fittings
Does anyone have a list of suppliers and a list of part numbers or sizes of fittings that would cover most or all of the air fittings on a 1998 shell?
When I go on line to look for fittings there are so many choices that I am not sure which ones are the right ones. The cost is high enough that I do not want to waste time or money ordering the wrong thing.
My guess is that 2 or 3 sizes would cover most fittings? I would like to order a supply of fittings and slowly start replacing all the push in fittings as I get the time. Any help would be appreciated.
I know that both mini air bages on the fan need to be replaced along with the fittings on them. I also have a leak at the fitting on the “Converter supply” valve that feeds the mini air bags. So I will start there and work my way to the front.
Thanks
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23 Replies
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Andre,
In that process myself. I have found that these are the sizes I’ve ran into:
All in DOT Compresion brass fittings
3/8 pipe to 3/8 hose straight
3/8 pipe to 3/8 hose tee
3/8 pipe to 3/8 hose 90 degree and 45 degree
The below sizes are also needed in Tee’s, 90 degree, 45 degree, and straight
1/4 pipe to 3/8 hose
1/4 pipe to 1/4 hose
1/8 pipe to 1/4 hose
The lines for the belt bellows (bags) are all 1/8 pipe to 1/4 hose 90 degree on fan and OTR a/c. The hose connecting the 3 bags are #4 Braided stainless lines with AN fittings.
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Unless you wish to get under the coach and make an inventory list the next best thing is to pull up the pneumatic diagram for your coach and blow it up to about 40 X 30 so you can see the details clearly. They are PDF files so some place like Kinkos can print the drawing.
The diagram is quite accurate showing the fittings so you can see where you need straight or ell or even 45 degree fittings, tees, etc.
The problem lies with the use of push in fittings not always being directly interchangeable with compression fittings although the ends match. On my coach I have several manifolds with 90 degree male pipe to tube fittings, but the 90 push in fittings swivel so they can be threaded in together, side by side. A compression 90 will not swivel so some creativity is going to be required, such as using nipples to adjoin fittings so each succeeding fitting is at a different height from the manifold and can be turned to tighten. I have to go through the exercise at some point in the future and the cost of fittings is going to be insignificant compared to the effort to make the changeout and get it leak free.
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sleeve and insert – each size– you can reuse nuts etc but need new sleeves and inserts… mistakes happen and they are cheap.. Bob
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Thanks for all the help. Does anyone have a recommendation for a on line supplier that has good prices?
Robert, if I understand what you said, I can use the correct size insert and compression sleeve on any fitting?
Example: if I have a 3/8″ fitting, I can put a 1/4″ insert and compression sleeve and use the 3/8″ nut?
Looks like sleeves and inserts are real cheap compared to the fittings.
I found this site when I was looking and noticed a BIG difference in price between these 2 manufactures.
Northway
Eaton Weatherhead
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each air line will require sleeve and insert to that size– A pvc cutter cuts air line neat and square–square being important.. teflon or better tape for threaded fittings is a plus… bob
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Andre,
I ordered all mine from Grainger mainly because they had the big stuff I needed, 5/8 and couldn’t beat the price.
For easy to reach places such as the steering bay, the DOT push on’s that swivel have been leak free. I know I’m repeating myself….
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My local ace hardware store has all the comp fittings try Ace hardware ,I did all mine not one push in fitting on coach now , leak free on all three gauges , I even did the three gauges with comp fittings six total got those from Fort Gary ……
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Am I missing something here. I have replaced a lot of my compression fittings on connections from norgren valves and to the micro flush toilet with push type. By design, they have a greater area of sealing. They are little more expensive and I only use DOT.
Most units in the transportation industry have been using the push type for years. Have proven their success.
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Don’t apply to our coaches where minor leaks can cause us to cry.. Well within tolerance for trucking or seated coach operators. When your trying to maintain a air system for days without running a air compressor often is when the differance come in play.. The newer more convient push type are less tolerant of temperature change and other factors we deal with.. Bob
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Darrell,
I think the problem is the push in tend to leak over time. It would be great if when they leaked they blew air out, but they seem to lose the seal starting with a very little leak. So your coach takes 6 days to lean instead of 7. And over time that becomes 5 days, then 4, etc.
The problem all of us that have really chased leaks realizes is it isn’t just one big leaking fitting, it is dozens all losing a bubble of air per minute making them difficult to find, but collectively really making a big problem. But the second concern is not only does the seal leak over time, if for some reason you have to replace a single valve or air bag, disturbing an old fitting is almost always going to end up with a leak, even if the end of the tube is cut off to renew the sealing surface.
A compression fitting can be taken on and off quite frequently, but the best news is when one is leak free, it stays leak free unless the fitting develops a crack which is rare.
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I did my hole coach with DOT comp fittings it’s worth it , and installed ball valves on all acc lines to isolate leaks !!!!
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I’m in the process of chasing leaks. I have replaced many fittings so far. All of them that were leaking were push ons. I have not found any leaking that were compression.
I’ve replaced all so far with DOT compression fittings.
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I found one 90 degree elbow cracked on tag valve beside drivers seat , very easy to miss that!!!
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Peter,
I just deleted 9 of your duplicate posts. What’s up?
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It seems to be our life chasing those leaks… lol
The leaks that I have chased in the past were the compression fittings from prevost or previous owner. In most cases, repetitive leaks from the same connection. I think the cause is over tighting of the fitting or offset of the compression ring. For most, lack of experience in the proper tightning / torque will cause this.
I love the ease of the PTC, especially in the areas that you have to stretch your arm and torque your body just to feel the connection in the dark because you cant position your flashlight with your teeth.
Ive had my coach for six years now and have replace many connections with D.O.T. PTC and have had no issues but still chasing compression fittings. Maybe years done the road the PTC fittings will give me a little grief but my experiences with my fire apparatus and public works fleet seem to be holding strong over the years. Keep in mind, the technology of PTC has improved significally from 8 to 10 years ago, so I do have a little faith in PTC.
Hey, if anything, its the best way to get to know your coach and peumatic systems.
Attention span of a fly,(thats me). While searching and processing your leaks, you always come accross something else that is more interesting. Love it!!
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