Author Topic: Air hose/tank fittings  (Read 3370 times)

Bill Drout

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Air hose/tank fittings
« on: February 17, 2020, 02:41:50 AM »
I have an air leak in the hose connection coming out of my air tank on my 1998 Patriot.  The picture below shows the fitting.  Not in the picture is the nut that goes over the fitting that threads to the open connection on the tank shown in the background.  Does anyone know what this fitting is called?  I'm thinking the leak is caused by the flat blue o-ring seal hardening from age and no longer sealing.  Does anyone know where to get replacement seals?
Bill Drout
1998 Beaver Patriot Monticello - 40'
CAT 3126B

Jim Nichols

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Re: Air hose/tank fittings
« Reply #1 on: February 17, 2020, 03:27:50 AM »
Remove the 90  elbow and take to Napa Auto/Truck parts store. Probably 5/8 threads 1/2" air hose slip on for the air line. Hopefully enough air line to cut the end off and slip into the new.
Jim/Natasha Nichols
05 Monterey 36'
400 Cat C9
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Mike Shumack

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Re: Air hose/tank fittings
« Reply #2 on: February 17, 2020, 11:23:56 AM »
That is a "air line compression fitting". The brass "band" is what does the sealing. Usually they are smooth (like a wedding ring).

My coach was built with the "Push-To-Connect" style fittings. These are great for assembly line work but not so good for coach owners (they always leak and are hard to impossible to get the line out of for replacement). When I come across a leaking PTC fitting, I replace it with a standard "Air Brake Compression fitting. I just cutoff the nylon air line at the fitting - as most of the time you cant get the old line out of the old PTC fitting.

The most common sizes on our motor coaches are 5/8", 1/2", 3/8" and 1/4". Your photo looks like the line is for the tank drain, so 1/4 inch air line (with 1/4 inch NPT threads going into the tank) is most likely what you have there.
« Last Edit: February 17, 2020, 12:43:30 PM by Mike Shumack »
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Lee Welbanks

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Re: Air hose/tank fittings
« Reply #3 on: February 17, 2020, 02:30:12 PM »
Bill, What your looking at is a compression air brake fitting that somebody has over tightened, that blue ring is the air line that the ferrel has cut into.
Remove the elbow and figure out what size you need, most truck shops will have air brake fittings not many auto parts stores will have this type of fitting. If you know the size you can get them from amazon or many other suppliers on the web.
Just make sure that what you replace this with is a "DOT brass air brake fitting".
You can get brass compression fittings at hardware and home stores but those are not approved for air brake systems, so don't go there.
« Last Edit: February 18, 2020, 02:47:35 PM by Lee Welbanks »
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Dave Atherton

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Re: Air hose/tank fittings
« Reply #4 on: February 18, 2020, 02:43:28 PM »
Gentleman, in addition to use of DOT fittings on they make perfect air tight seal for diesel fuel lines . One thing many do not understand
with connection with air fittings is the steel insert that goes inside the center of plastic air line. Some fitting the insert is in the fitting but many cases has to be bought separate. Dave Atherton Retired Cat Mechanically
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Lee Welbanks

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Re: Air hose/tank fittings
« Reply #5 on: February 18, 2020, 02:51:43 PM »
Gentleman, in addition to use of DOT fittings on they make perfect air tight seal for diesel fuel lines . One thing many do not understand
with connection with air fittings is the steel insert that goes inside the center of plastic air line. Some fitting the insert is in the fitting but many cases has to be bought separate. Dave Atherton Retired Cat Mechanically

Dave, I took all the plastic Voss fittings out of my fuel supply line from the tank to the lift pump on the motor, the Voss fittings have a O-Ring in them that will at some time start leaking and the fuel system will start sucking air, don't want to go down that road. Replace here at the shop instead of alongside the road somewhere.
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Bill Drout

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Re: Air hose/tank fittings
« Reply #6 on: February 20, 2020, 08:32:13 PM »
Wow, great info.  Thanks for everyone's contribution!  As you know, purchasing a motor home is quite the learning experience.  I'm a lot smarter on this topic now.

Thanks Again!
Bill Drout
1998 Beaver Patriot Monticello - 40'
CAT 3126B

Lee Welbanks

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Re: Air hose/tank fittings
« Reply #7 on: February 21, 2020, 12:29:22 AM »
This forum is the place to find out just about anything you want to know about a Beaver motor home, if you have a issue just post the question and somebody will have the answer or let you know where you can get that answer.