Replacing copper lines with DOT poly air-hose

I've had some personal questions lately about using DOT poly air-hose. A lot of people are worried about the cost of fittings an such. Just to set the record straight it is cheaper by far to use poly hose then continuing to use the copper lines. In fact you don't need to replace the fittings at all. Just the insert and ferrule and of course the hose itself. You can buy the stainless steel inserts in bulk along with the ferrules and hose at any "Parker" hydraulics store. These pictures show how the original fittings don't have to be changed out.
Poly air-hose is far superior to copper lines. It doesn't work harden and can bend without kinking and can take a hit from a rock or other road debris and bounce back. It is far easier to use and install and you only need a small 20ft roll (10" X 3" ) tucked away for emergency repairs.
Picture one shows a standard copper line and fitting connection. Picture two shows the fitting and the new insert and ferrule. Picture three shows the poly hose with the old crush sleeve and the new insert and ferrule. Picture four shows the new assembly together. Picture five shows my connector on the firewall with one side still using the copper line and the other side using the new poly hose.

Nice....!!

The air brake Poly is super, especially when it comes to vibration. Another use for it is fuel line. It will last forever. Here, in the colder climes, we never go anywhere without an independent source of heat.... namely the propane bottle & tiger torch (weed burner & sometimes a joint of 6" stove pipe with an elbow on one end). As careful as one can be, regardless of the system that you use, its a matter of time till you have a freeze up in your brake system. You must be very cautious, thawing things out, but its doable.

Good Trick Rusty. I didn't realize the the old compression fittings would accept the the DOT ferrule & insert.

rosco said:

Good Trick Rusty. I didn't realize the the old compression fittings would accept the the DOT ferrule & insert.

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I would have mentioned it a few years ago when I started posting about using poly hose, but I ASSumed everyone knew about it. Working in the truck and heavy equipment industry this is a common conversion. I've just always replaced the fittings with new just to be sure there would be no problems, like a crack or busted fitting. If you do replace all the fittings like I do it can get a little pricey, but you don't have to, to make it work.

I've been wondering about that lately myself.

Thanks Devil Dog!!

I would recommend checking the temperature rating on the tubing you are using if using it directly on the compressor. You would be better to leave a bit of copper from the compressor out to allow for heat dissipation and to keep the poly tubing from melting.

Good tutorial Rusty.
JC

Eliteweapons said:

I would recommend checking the temperature rating on the tubing you are using if using it directly on the compressor. You would be better to leave a bit of copper from the compressor out to allow for heat dissipation and to keep the poly tubing from melting.

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You are correct you don't want plastic coming off the compressor because of the heat , it's been discussed before.
[h=1]dot approved copper tubing between compressor to air tanks[/h]

rosco said:

The air brake Poly is super, especially when it comes to vibration. Another use for it is fuel line. It will last forever. Here, in the colder climes, we never go anywhere without an independent source of heat.... namely the propane bottle & tiger torch (weed burner & sometimes a joint of 6" stove pipe with an elbow on one end). As careful as one can be, regardless of the system that you use, its a matter of time till you have a freeze up in your brake system. You must be very cautious, thawing things out, but its doable.

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Check the hose markings and manufacturers specs. "most" air brake poly is NOT rated for fuel and specifically excluded by the manufacture in their warranty statements.

juanprado said:

Check the hose markings and manufacturers specs. "most" air brake poly is NOT rated for fuel and specifically excluded by the manufacture in their warranty statements.

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The Parker brand hose is.

Eliteweapons said:

I would recommend checking the temperature rating on the tubing you are using if using it directly on the compressor. You would be better to leave a bit of copper from the compressor out to allow for heat dissipation and to keep the poly tubing from melting.

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I used stainless steel PTFE hose for the first 5 feet. Since this was discussed in length before I thought everyone was on the same page.

Here's my hose. I wrapped the PTFE hose with a heavy duty poly wrap just for extra protection.

rustystud said:

The Parker brand hose is.

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I was in parts for 20 years and attended many vendor "tech" clinics. When I sold weatherhead for Napa, I attended a clinic as Weatherhead has hoses and fittings from A-Z. The number of sku's for fittings is unreal. It is really an art to know fittings and sell the correct ones and few parts stores can carry the massive $ needed to fill all markets.

One of the things we were taught is that air brake tubing is not "DOT"certified for fuel. There is a different spec and sae standard for it. I have bookmarked the catalog pages for you to review. Poly hose for fuel is rated and stamped differently. Yes, I know it works and is a quick fix but not the right stuff.

I don't mean to argue but just inform. If the wrong hose leaks and causes a fire, guess what is the first thing looked at....

When I replaced my deuce return lines, I used some of of the cheap poly tubing from Lowes I had lying around (not DOT rated). That stuff turned soft in no time. I replaced it with some DOT tubing and no issues after that.

juanprado said:

I was in parts for 20 years and attended many vendor "tech" clinics. When I sold weatherhead for Napa, I attended a clinic as Weatherhead has hoses and fittings from A-Z. The number of sku's for fittings is unreal. It is really an art to know fittings and sell the correct ones and few parts stores can carry the massive $ needed to fill all markets.

One of the things we were taught is that air brake tubing is not "DOT"certified for fuel. There is a different spec and sae standard for it. I have bookmarked the catalog pages for you to review. Poly hose for fuel is rated and stamped differently. Yes, I know it works and is a quick fix but not the right stuff.

I don't mean to argue but just inform. If the wrong hose leaks and causes a fire, guess what is the first thing looked at....

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Our fleet of busses have been using DOT approved poly hose for decades now as the main fuel and return lines. Never had a leak that I saw in 24 years there. This is the same hose as the air supply hose. It will say DOT approved on the hose. We had 500 foot reels of the stuff in the back supply room.
Also when I worked at IHC in Tukwila WA. all the 1978 and newer trucks came with DOT air hose for the fuel lines. That is where I got the idea in the first place to convert my vehicles that had rusted fuel lines.

juanprado said:

I was in parts for 20 years and attended many vendor "tech" clinics. When I sold weatherhead for Napa, I attended a clinic as Weatherhead has hoses and fittings from A-Z. The number of sku's for fittings is unreal. It is really an art to know fittings and sell the correct ones and few parts stores can carry the massive $ needed to fill all markets.

One of the things we were taught is that air brake tubing is not "DOT"certified for fuel. There is a different spec and sae standard for it. I have bookmarked the catalog pages for you to review. Poly hose for fuel is rated and stamped differently. Yes, I know it works and is a quick fix but not the right stuff.

I don't mean to argue but just inform. If the wrong hose leaks and causes a fire, guess what is the first thing looked at....

Click to expand...

When you compare the hoses you will see the only difference is the color. The specifications are all the same.

When the Poly hose is plumbed on trucks for the air brake system, it stands to reason that it is immune to petroleum products, as it is subject to all kinds of leaks around the engine & transmission. Knowing that, I first plumed a farm tractor's fuel system some 20 years ago, and its still running strong.

The poly hose fittings are just about fool proof too, & one just doesn't find the fittings leaking. Suprizingly, it even stands up to extreme cold, as in -40 & -50F.