Air in the workshop

Hi All,

As I have a portable compressor, but only want to move it when outside, I thought I would put in some permanent piping to areas where my machines are, I also have an airbrush booth. What would be the best 4to use considering the pressure would be no more than 60psi?

I thought of either plastic water pipe with push in fittings or 15mm copper qnd associated fittings.

What are your thoughts peoples?

Cheers

Roger

Edited By Roger Clark 1 on 30/05/2017 12:16:43

Metal pipe or rubber hose. Never plastic!! I'm now going to duck for cover because there are those who will beat this to death....

Pete

There is plastic push-fit pneumatic piping (I have used some in a couple of boxes to allow cargo rollers to rise out of the floor) and that's OK up to 100 psi. See no reason why water pipe of whatever diameter you find cheapest shouldn't do just as well. Copper pipe is more expensive, but capillary fittings are cheap & effective. Plastic pipe is cheap, but the fittings more expensive. How hot does the compressor tank get? That might be the thing that determines your material choice. If too hot, wouldn't want plastic.

Regards,

Richard.

The biggest problem with standing piping is condensation so ensure water traps and filters. A fixed line can be the specialised plastic and the mating connections( I have only seen a Blue colour pipe) Normal 15 mm copper as well. The longer the run the more condensation you will get. You need to make sure the lay is not flat but leads down to a drain tap. having the compressor outside can also lead to problems with the cold air.

There are air piping and filter suppliers so a visit is worth while.

Clive

Depend on the plastic doesn't it?. High pressure Gas Main is plastic.

regards Martin

Push fit Nylon Pneumatic is cheap enough, you can go the extra mile and fit the blue ridgid airline by the likes of John Guest but a coil of the Nylon hose and fittings are easy enough to get from e-bay or Toolstation do teh John Guests Nylon stuff. I recently made up a small manifold for running my engines at shows with the Nylon.

Peter, it would be interesting to know why we should not be using plastic rather than just saying "don't"

Edit. PVC changed to Nylon.

Edited By JasonB on 30/05/2017 15:43:14

Common grey PolyPlumb et al water pipe and fittings have a rated maximum pressure of around 18 bar (just over 200 psi). Pipe carries more. 100 psi is a commonly advised test pressure for complete plumbing installations. Seen suggestions that 10 bar (140 psi) should be used for testing. So it ought to be up to the job. Can only be got in smaller bores tho' which won't worry you.

The big no-no is PVC pipe as that shatters when damaged sending sharp plastic shrapnel all over the place if you hit it when full of compressed air. Nasty. It can also let go of its own accord if it develops a weak spot. Repeated changes in temperature can cause such. Weakens rapidly when warm too. So don't use drainpipe despite folk saying they have used it for years. Was once allowable if buried or completely covered but that was a heftier pipe than you'd find now.

If the runs aren't that long worth checking relative price of ordinary flexible air hose. Could be cheaper to string some of that around the place, maybe doubled up for more flow, than doing a proper plumbing job. When I looked into doing my, rather large, workshop a simple recoil hose system was lots cheaper than properly plumbing in. So thats what went up "for now" to be done right when all the machines were in. 12 years and counting its still not been done over.

Clive.

Like it or not 25 years ago I plumbed out my garage using Hep2o piping, which was brown and called Acorn when I did it. Since then I have had zero leaks and can't fault it in any way. The system runs at about 90-110 psi and I use snap on air fittings. I may change over to euro fitting as these have a larger aperture for the same size of fitting.

https://purplemotes.net/extras/diver.jpg

I plumbed my workshop out with 15mm copper & brass fittings its burst pressure is 852 psi when i checked it, its been up without issue for years in my mates place and around a year in mine. all the fitting etc were readily available at my local builders merchants

Tony

To allay potential confusion there is a considerable difference between flexible "PVC" hose and rigid PVC pipe.

Flexible PVC hose is processed and blended differently, eg PVC-nitirile blend, and often has an extra layer of a different plastic to protect it from mechanical damage. Often with reinforcing braid. Sold as air hose and clearly safe to use as such. Personally I find it on the stiff side for flexible hoses and prefer rubber.

Its the rigid pipe that must not be used.

Clive.

Not an expert in this subject but would suggest checking that the pipe/tubing used is suitable for use with compressor oil as there will, no doubt, be some carry over.

One other concern is the flow required which will be limited using the above blue small bore plastic, ok for for air gun blowing, drills and grease guns. Few years ago was spraying with mini spray gun 50-60psi Soft Touch clear and constantly fighting reg pressure and gun flow rates. Turns out it was the feed of the flexy coil with bore 1/4". Regulators are 3/8" to 1/2"BSP in line so not much of a restriction to the flow. 1/4" there will be.
Have similar with bead blaster always up and down when use the small coil, 1/2" bore no problem.

Just modified existing layout about 4 weeks ago, I used the 15mm copper with various U bends built in, stop cocks, regulators and quick releases originally done about 7 years ago to plumb in my old compressors tank.
Copper pipes cheap and can use the ready soldered elbows, T connectors etc or the compressable ones. Leftovers come in handy for repairs for central heating and water repairs.
Next year additional tank will be moved in to another building with bead blaster and hard wired in underground which should cool the air down.

At work we use 12/15 mm as mains into a machine and 6/8 mm from valves to actuators etc up to 8 bar, its perfectly safe and doesn't harden or fracture, it can be got in a variety of colours, Black, Red and Dark and light Blue in 30 metre rolls from any Pneumatic stockist along with the Pushin fittings. If you use copper then put a couple of drops in the line with drain taps on the ends to catch the condensation.

Martin P

Jon, the flexi Nylon can be had upto 16mm OD x 13mm bore, which is no smaller than 15mm copper. John Guest stuff goes larger.

No need for joints in long runs, no risk of flux left from jointing causing corrosion inside the pipe, push fit makes it east to alter and adapt

I would endorse Jason's comments. when I did mine I used rigid nylon tube and fitted it inside the 2" square conduit carrying the power supply. I made a ring main and dropped down at convenient points and fitted a quick release coupling at each drop, and all my pneumatic equipment has the matching fitting so can be plugged in where required. The right tube and fittings are available everywhere all to the standard sizes and they are cheap as chips, easy to install, no heat required, so why use something not designed for the job?

Chris Gunn

My workshop is fitted out with 15mm copper, half hard with all joints soft soldered so the copper is not annealed at the joints (some would suggest brazing the joints however this anneals the copper and therefore reduces the pressure at which it can safely be used - in addition, excessive heat can severely weaken the copper in the area immediately surrounding the joint).

Someone earlier mentioned using 'ready soldered' joints. These are commonly termed 'solder ring or Yorkshire' fittings. In an airline I would strongly suggest avoiding these. The swaged area which contains the solder ring can, if not properly soldered, create a weak void in the joint. I advocate the use of end feed fittings in air lines. When correctly soldered, we have proved that these create a mechanically superior joint to solder ring fittings.

In order to create a strong joint, ensure the pipe and fitting are thoroughly cleaned with wire wool. Use only the bare minimum of flux (I have seen joints fail because flux was plastered on like butter, excess does nothing to assist in the joint and will over time corrode the copper and the solder causing premature failure). Heat the fitting and the pipe so that the solder flows easily (don't heat the solder directly)

All of my joints are made with lead free solder and a non aggressive flux, the entire system was flushed with a flux remover to remove any residue.

I have tested my system both hydraulically and pneumatically to 20 bar (almost 300psi) and run it happily at 10 bar.

I have a chiller/condensation trap between the compressor and the 150 Litre accumulator tank, all of the horizontal runs have a slight fall on them and end in condensation traps/drains with the outlets tee'd off above the traps. At each drop there is a pressure regulator with its own water trap and automatic drain valve, and the outlet for the power drawbar has a water trap and automatic oiler.

This may all sound a bit of overkill but I have 6 machines running a mixture of conventional and fogbuster type coolant systems and power drawbars on the 2 mills plus a pressurised coolant system on the cylindrical grinder so having a fully plumbed in shop air system was a need to have.

With a copper pipe installation ensure that the pipe runs are correctly supported, horizontal runs should be supported at no more than 1.2 Metre intervals, vertical at 1.8 Metres.

One thing to keep in mind about soft plastics as used in tube is that any impact can cause the pipe to partly collapse and yield. If you see white marks at a kink or impact site the tube has yielded. The strength at such a yield site is a small fraction of the tube's normal strength. In home workshops space is often limited and things get banged into other things and heavy sharp objects get leaned against things. If these "things" are tubing under air pressure there could be a kinking/yield problem. If the tubing is never damaged it seems safe enough (as well proven in the pneumatics/automation industry) for pneumatic service in small diameter sizes say 8 mm or below up to 150 psi pressure but I have heard of industrial incidents with larger dia compressed air tubing failing shrapnel style and causing injuries.

Do please remember that the strength of soft plastic tubing falls off rapidly over 80 deg C or so, with many types of soft plastic starting to melt at 130-150 deg C. Compressed air straight from the compressor can be very hot.

Most soft plastics as used in tubing have tensile and impact strength a fraction of the strength of even low quality copper, aluminum, or steel / iron at 20 deg C.

As stated before in other threads I have long experience designing, making, and testing plastic parts in industry, and my opinion is that no plastic, hard or soft , is suitable for use as a pressure vessel for steam service at any pressure regardless of whether a woven stainless jacket or other covering is applied or not. Going further, I don't trust it for hot domestic water under pressure either, even though it has been lobbied for and accepted into building codes in some areas of North America. Even cold water under pressure has caused problems with soft plastic tube in domestic water supply plumbing here in North America, when installed carelessly with resulting kinks in the tubing. The only real reason manufacturers lobbied for its' adoption for water supply plumbing was lower manufactured cost (higher profit margin for the manufacturer) and faster installation (higher profit margin for house builders). I predict many flooded basements, long legal battles with insurance firms, and product recalls for plastic water supply tubing systems in future.

My vote goes to 3/8 or 1/2" NPT threaded black iron pipe for compressed air systems (with frequent condensate draining), and soldered 1/2" or 3/4" copper for water systems. Plastics are fine for drains not under pressure.

Just my $0.02 worth. JD

When our new hanger was built in 1966, we plumbed in the air supply with 1/2" galvanized water pipe, it seemed to work OK.

Ian S C