I'd like to distribute the output of my compressor to various outlets around the (large) garage to minimise hoses everywhere when using air tools. I can easily buy 1/4" BSP quick-release air fittings, however, can I adapt these to fit onto 15mm copper pipe, and will "standard" copper pipe be OK for the
100PSI (max) pressure invoved? I'd solder the copper joints and presumibly have a compression fitting to adapt to the 1/4" BSP fitting.
The connection to the compressor would be by a short flexible hose to the wall mounted distribution system.
Can anyone recommend a source of the adaptors? Is copper pipe up to the job or should I consider something else?
There may be some regulation against the use of copper for this application. All garages/factories I have seen use glavanized steel pipes.
It may just be conservatism on the part of the installers but the penalty for using steel is so big on the install that I'm inclinded to think that there may be a safety reason. The stroed energy in even a small compressor tank is large.
There is no problem converting from 15mm to 1/2" and from there using bushes and nipplesto 1/4".
I second Grunff's vote for 25mm mdpe. I run it around two workshops and an underground run of 120' to my foundry at the bottom of the garden, and have had no problems whatsoever with it over 15 years.
In the US on various metal working use groups they get very excited that pvc shouldn't be used as it fractures and shards fly everywhere, by I think their pvc 'water line' is much more brittle than our mdpe.
PVC is a very different beast - it's completely dependant on it's plasticiser content for flexibility. Lose that plasticiser over time and you have very brittle pipes.
MDPE OTOH is very soft and ductile - I'd much rather experience a burst MDPE pipe than just about any other material.
I looked into this a couple of months ago for this application but have not implemented anything as yet.
I did some web searching and specific information seems to be scarce.
The best resource that I found was the web site and literature from a company called Thomas Wright Ltd., with branches in Lancashire and Yorkshire.
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They sell everything needed and more for compressed air systems, pneumatic controls etc. etc.
There is a publication called "Pipe Up" orderable from their web site which describes how to build a workshop airline using either Table X copper tube and compression fittings or a push fit nylon system. It gives some typical designs including the arrangements required to prevent water being carried to the outlets, how to hook up the compressor and controls such as filters/regulators/oilers.
The plastic system is rated up to 10 bar @ 23 degrees and 7 bar @ 70 degrees, whereas the copper is rated to 10 bar @ 30 degrees. Both are said to be suitable for use with compressors up to 15HP.
There are comments to the effect that plastic should not be used where there is a risk of mechanical damage.
For the copper, it does specify that compression fittings should be used. Not in this leaflet, but I remember reading somewhere else that soft soldered fittings should not be used for compressed air services, but I can't find it.
Finally, in the booklet it does mention that some users and owners of compressed air systems are responsible for complying with the Pressure Systems and Transportable Gas Container Regulations and that Thomas Wright company is a "competent person" for these purposes.
Further digging revealed that this regulation has been replaced by the Pressure Systems Safety Regulations, 2000.
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is very familiar terminology in this SI referring to "competent persons" etc.; but I could find no such definition.
I read through the SI fairly quickly and it appears that the requirement is that a "written scheme of examination" must be drawn up and executed by a competent person.
However, like quite a lot of HSE related legislation, it appears that this applies to installations in places of work. However it does include installations used by the self-employed as part of their work.
There is a paragraph in Thomas Wright's booklet to the effect that they can advise regarding the requirements.
They do also sell steel pipe and fittings, but this is not covered in the design guide.
15mm copper pipe isn't spec'd to take the sort of pressures generated by a compressor.
You're better off using flexible compressor hosing and suitable fittings. I can take some photos of how I realised a compressed air distribution system if you like
Really? I've got a (not particularly recent) IMI Yorkshire Tube data sheet in front of me. For BS 2871 Table X tube in 15mm size it says that the max. working pressure is 58 bar (when used in conjunction with Yorkshire fittings). What sort of air compressor did you have in mind...?
This subject has come up before, at least twice, IIRC. Go Google.
Bundy tube (thin wall galvanised steel) is the usual stuff for airlines under about 1/2" or so. Not only will it take the fittings without needing to adapt them, but it should be cheaper than copper. Look for any airline supplier in yellow pages or a trade directory. When copper is used for airlines, it is normal to use fully annealed copper, but that may be because copper tends to be used only where there are difficult shapes to make.
Data I have for galvanised steel pipe specifies a maximum working pressure for water that is double that for compressed air. The safe working pressure is also rated at 1/3 of the maximum working pressure. That would give 15mm copper tube a safe working pressure with compressed air of a little under 10 bar. However, my recollection is that compressed air is not one of the uses the manufacturer specifies for this tube.
I would presume it would be for any approved use. The pipes I have data for are approved for water, steam, compressed air and non-corrosive gasses, hence they have data for those.
I thought it was specifically 'gas', which I have always taken to mean town or natural gas, the pressure of which is measured in inches of water.
There's a publication on the CDA web site called "copper tube in buildings" which states, amongst many other things, that "copper tubes and fittings are also suitable and widely used for [...] chilled water & refrigeration, fire sprinkler systems, air conditioning, steam, medical gases, pneumatics, hydraulics and waste water.
I'm still inclined to suspect that the use of steel for air-lines is more to do with tradition than anything else. But ICBW.
And really imho iron / steel pipes should be avoided if only because they WILL eventually rust inside from the condensation in the compressed air. Instructions for running galv or black iron air services always used to include a 'dead vertical stub' where a vertical run meets a horizontal one, comprising a Tee with a dead stub pointing downwards to catch the rust flakes in a place they could relatively easily be removed.
"nightjar" > The data sheet refers to "gases" without being any more specific.
15 mm copper tube is approved for the distribution of gases in laboratories and hospitals. Oxygen is commonly provided to the bedside via 15 mm tube with soldered fittings.
I spoke with Thomas Wright Ltd (mentioned earlier) on this.
They sell and install systems as well as the components and told me that various pipe materials are used, including steel, copper (standard table X), nylon and more recently aluminium (also with push fittings - apparently this is popular in continental Europe.
I asked them to contrast the different methods, and they did comment that this is an industry with conservative habits.
Steel is popular through tradition and cheapness, but is hard work to install. One needs to have the ability to thread the pipes and installations have to be done in a specific order so that the pieces screw together in order.
Copper is also widely used and generally they recommend compression fittings for ease of installation - again it was what is commonly used
- although apparently there is not an issue with using solder fittings if preferred.
Nylon is used for speed and ease of installation, but not recommended where there is a risk of mechanical damage. Overall, the material costs including fittings are similar to copper if compression fittings are used with copper.
In all of the cases, it is recommended to design the system as a loop run high up around the workshop with a drop to take the feed from the compressor. A drip leg with an automatic drain is recommended for at least one corner and the pipework should be arranged to slope to this point. At each drop point to an outlet on the wall, there should be a tee pointing upwards and then two elbows to take the pipe down the wall. This avoids water running down the outlet drops. Regulator/filter/lubricators can be fitted as required.
Copper will be fine, you just have to make sure you use either compression fittings or HARD soldered (brazed) joints. That's how all the medical gases in your local hospital are piped (working pressure max 7 bar).
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