Thread: Using poly (pressure) pipe on Air Compressor

You seem to have your pipe material terminology wrong. You mention having glue but polyethylene or poly is not glued as it has a resistance to solvents. Poly can be fusion welded or use compression fittings. Polyvinyl chloride or PVC fittings are solvent glued and if used in high pressure applications such as an air line will not last well in a workshop environment (PVC is brittle) or even explode like a pipe bomb.


Poly pipe for pressure applications such as air is easily recognisable by the light blue colour and as it is denser than poly water pipe so it comes in straight lengths not rolls. Gal pipe is a bit more difficult to install but assists condensation occurring before air line/tool. Poly fittings are expensive so design to reduce their number.

Don’t use air hose as fixed lines even if only going 5 meters. The fixed line needs to have a larger diameter to limit volume/pressure loss due to friction i.e. 32mm longer main lines and 25mm for branches. Take main fixed line direct from tank or a T off before tank regulator and use a flexible connector or motor vibrations will break the join. Fall main line towards the air hose end and finish with a vertical drop with a gate valves at the end to drain of condensation and horizonal T off above that with a regulator/filter/water trap for the air hose. Use 10mm (not 8mm) air hose and keep length to a minimum or better still fit regulator at tool end.

You need Blue Line Poly - PN12 (170psi) or better - It's mechanical, not solvent weld joins (blue/green glue). The pessure rating is MAX working. Burst is generally 2-3 times this amount. You can use White PVC Pressure pipe, in PN12 or better, which can be glued, but poly is a better choice for your application.

You'll need to do a short run of something metallic (Gal/brass/copper) from the compressor outlet to the poly pipe (as a heatsink), as the temperature at the compressor outlet will cause the poly pipe/fittings to fail ... poly or PVC is NOT suitable for high temperatures.

A LARGER pipe will give LESS pressure loss (friction loss), and get you MORE pressure at the working end .... this is dependant on FLOW RATE ... the more CFM you want to move, the BIGGER the pipe needs to be to minimize the pressure loss.

Also, if using blueline PN poly, remember that the dimension quoted is OD, so a 32mm pipe is actually only 25mm ID ... so, if you want a 32mm pipe, you need a 40mm pipe. You roughly loose a size due to the wall thickness of the pipe in PN12/16 grades.

OK, I have got the nomenclature off the side of the poly pipe, which is:
- Iplex S1 PVC PN15
It is hard, white and is in 6 metre lengths.

I can see that it might be too brittle for air lines.....

Originally Posted by blitz

Why not use hard drawn 19mm copper tube?

copper isn't to expensive, easy to solder and it is probably more commonly used than any other medium for this purpose.

as your in the Adelaide hills I can give you a hand fitting it if you want.

If you know about copper pipe and how to solder it, that'd be excellent.

I don't have any gas welding equipment, but I do have a TIG welder, and I gather you can use this on copper. I'd have to get some of the proper welding rods though.

I am in Balhannah, on Greenhill Road, so about 2 or 3 Kms from Hahndorf.

Originally Posted by cockie55

Don’t use air hose as fixed lines even if only going 5 meters. The fixed line needs to have a larger diameter to limit volume/pressure loss due to friction i.e. 32mm longer main lines and 25mm for branches. Take main fixed line direct from tank or a T off before tank regulator and use a flexible connector or motor vibrations will break the join. Fall main line towards the air hose end and finish with a vertical drop with a gate valves at the end to drain of condensation and horizonal T off above that with a regulator/filter/water trap for the air hose. Use 10mm (not 8mm) air hose and keep length to a minimum or better still fit regulator at tool end.

I was planning to put the regulator close (1m away) from the compressor on the shed wall.

Then run 2 or 3 lines out from the regulator to 2 or 3 snap fittings placed around the shed.

If the regulator is 5m from the snap fitting, willl this give me inaccurate pressure over this distance? I'd have thought the pressure would be constant along all 2 or 3 lines (no matter the distance - within reason), so wondering why a regulator at the tool is better....

Originally Posted by spudboy

I was planning to put the regulator close (1m away) from the compressor on the shed wall.

Then run 2 or 3 lines out from the regulator to 2 or 3 snap fittings placed around the shed.

If the regulator is 5m from the snap fitting, willl this give me inaccurate pressure over this distance? I'd have thought the pressure would be constant along all 2 or 3 lines (no matter the distance - within reason), so wondering why a regulator at the tool is better....

So what are you going to run? As mentioned pressure loss comes from flow through the plumbing. So it really depends on your flow rate, and pipe size. The difference in pressure between your tank and the regulator will depend on the distance and flow rate. If the reg is at the tank your flow down the lines will cause a pressure drop from the reg, losing pressure at the tool. Does it matter? Probably not of the line is big enough.

With your reg by the work station your pressure drop from the tank to the reg may be insufficient to make a difference at the outlet. That is because the reg's job is to maintain a constant outlet pressure regardless of flow (within its limits of course).

Personally I would have a reg at each outlet (if needed) as they rob pressure at flat out rates anyway.

Originally Posted by spudboy

If you know about copper pipe and how to solder it, that'd be excellent.

I don't have any gas welding equipment, but I do have a TIG welder, and I gather you can use this on copper. I'd have to get some of the proper welding rods though.

I am in Balhannah, on Greenhill Road, so about 2 or 3 Kms from Hahndorf.

Amongst other things I teach soldering copper pipe for a living, I am a Refrigeration Trade Trainer and yes I have all the gear you need and i am happy to help you and teach you how to solder if you want as well.

i dont have the pipe but i can come and have a look at what you want and work out what you need to do it for you.

Originally Posted by blitz

Amongst other things I teach soldering copper pipe for a living, I am a Refrigeration Trade Trainer and yes I have all the gear you need and i am happy to help you and teach you how to solder if you want as well.

i dont have the pipe but i can come and have a look at what you want and work out what you need to do it for you.

Go for it Blitz, help him make a decent main trunk, remember compressed air pipes like a bit of fall back to the best drain point, and air should be taken from upwards facing junctions with u-turns down to the outlets. When I silver soldered my house sprinkler system I tended to use flare or compression fittings at 19mm or under because they are cheap and easy to modify.