Compressed air and PEX

[beech1948]

I have moved house and need to restablish my workshop. I have had access to compressed ait for the last 15yrs running through 22mm copper pipe with soldered joints which has been run upto about 120lbs pressure.

I was reading a US web site ( Garage Journal) and came across several threads about the use of standard PEX called PEX Boundary pipe overhere for running compressed air. Stopped me in my tracks as my first thought was it would be unsafe.

A little research shows that PEX is tested at upto 18 Atmospheres or around 215 Lbs/squ inch which again sounds a little out there.

Has anyone used PEX pipe and fittings to distribute air around a workshop. It must be cheaper/easier than copper or black pipe and more safe than PVC which I would not use.

 

[shed9]

When PEX is used for underfloor heating it is held under high pressure using an air compressor when first installed in the screed so in an indirect way it is kind of manufactured for compressed air to some degree. If I remember rightly the manufacturer install instructions recommended it (don't quote me on that one).

I ran an air compressor at well over 6 bar through several hundred meters for well over 48hrs without a hitch.

 

[Fitzroy]

At such small diameters the burst pressure of piping/tubing is huge, it'll be connections that are the weak point. For example refinery instrument tubing 12mm diameter with a wall no thicker than copper plumbing pipe, granted made from stainless steel, is good for hundreds of atmospheres of pressure. For fun I once pumped a plastic 500ml coke bottle upto 150psi before it popped, now that was a bang!

F.

 

[dynax]

For fun I once pumped a plastic 500ml coke bottle upto 150psi before it popped, now that was a bang!

F.

many years ago, i had a dozen or so 2 and 3 litre pop bottles that i made into air tanks for airbrushing,( i didn't have a compressor at the time and the cans of propellant were useless), i used to fill them at the local garage with free air,

 

[dzj]

Pex-Al-Pex variety are good for 10 bar and 95C.

 

[n0legs]

Haven't used PEX but went with some JG nylon and their fittings for a small install.
Absolutely gorgeous stuff to work with and quick, go on ask me about quick :lol:
Only down side it is a little expensive, but hey ho savings made in time and simple tools needed.
http://www.sturdyfluidpower.co.uk/Produ ... 0900020023
http://www.sturdyfluidpower.co.uk/Products/0049000a0015

 

[beech1948]

Ok then. Stand down all. 3 Pex manufacturers have refused to agree to allow their product to be used for compressed air and their tech documents clearly state NOT for air.

In any case further research reveals that nylon pipe is available with fittings for less than PEX so I'm going tp fit out the first wall of three air fittings with this nylon stuff.

Thanks very much for all replies

 

[shed9]

Ok then. Stand down all. 3 Pex manufacturers have refused to agree to allow their product to be used for compressed air and their tech documents clearly state NOT for air.

To be fair they wouldn't commit to a use beyond the stated purpose anyhow, however I would reiterate my note up there ^ that when it's laid for underfloor heating the pipe needs to be kept under air pressure and this is not unusual.

In any case further research reveals that nylon pipe is available with fittings for less than PEX so I'm going tp fit out the first wall of three air fittings with this nylon stuff.

Given the price of PEX can't say I'm surprised that there are cheaper alternatives.

I'd be interested in what you end up using and your opinions on it when you get it installed and eventually use it.

 

[RobinBHM]

John guest air pipe is available from toolstation

http://www.toolstation.com/shop/Power+T ... hop/sd2791

Ive had this installed for about 10 years no issues at all.

The system was extended a few years back with standard plumbing push fit and had no problems with that either. The hydrovane air compressor works at 8 bar and the system is generally on 40 hours a week.

 

[beech1948]

RobinBHM,

Thats good news then as that is the brand I have decided to go with. I would prefer more rigid pipe though than TS has on their web site.

 

[Robbo3]

Compression test of push fit fitting (spoiler alert = 750PSI)
- https://www.youtube.com/watch?v=I59OeSwrhEc