Hi guys. I'm looking for advice on setting up my compressed air supply.

I want some decent quality air out of it, which is not what you get out of a compressor.

I want cool, clean and dry air. At the moment, its hot, dirty and wet.

Does anyone apart from Moglite have any input on this subject?

I have heard that a good way is running copper pipe (for cooling) - possibly through finned tube, probably at least via a convoluted path - maybe through an intercooler, then a particle filter (or this first?), and a decent dryer then out to me tools (no oil needed in this case).

The cooler the air is by the time it hits the dryer, the more moisture I'm going to condense out of it, and the happier I'm going to be.

Does anyone have a decent air dryer they would recommend (that doesn't cost the earth, preferably)?

How about your setups - anyone using coolers? Filters? Driers?

Any input would be great, this is all new to me.

Thanks guys. Al.

The length of copper pipe i have means i get pretty much no water in my seperator, i don't have a dryer though.

I also have a 300L tank, that's quite a lot of steel acting as a heat sink.

cold air, should generally be dry air,

what size tank do you have?
what sort of duty cycle to you imagine? - having the compressor on all the time is going to produce hotter air to start with.

Hi Luke - for now I have a 150 ltr tank & 3 HP motor. The duty cycle would be 100% if the compressor could give it. Therefore the air will be HOT.

I'll need to upgrade to something less DIY, but even then I want the cleanest dryest air I can get for non-silly money.

Ebay is just Sealey and Draper and stuff, which is probably ok, but I'd like to aim a little higher. Typically Harbour Freight have some well priced dryers in the States, but we don't really have an equivalent here (Machine Mart is much worse).

I'm thinking of a primary passive cooler of a looong loop of copper pipe along a wall and back, and then into a cooler made from an old fridge I happen to have lying around (a fridge from Fridge, in fact ). Immediately out through a water separator, and then maybe have a secondary tank at the output end.

All that lot could be entirely separate from the compressor, so I could upgrade that later on (looks like I'll need to).

Any idea what pressure copper tubing is rated to (when used with air)?

Anyone know about separator types? the obvious one is a centrifugal one, as most people have, but I wonder if there is a better type, and preferably one which doesn't run through consumables like the dessicant or 'loo-roll' type ones?

Anyone have a secondary air tank they don't need?

Cheers, Al.

Hyphose sell all the various air prep equipment for industry, I'd suggest a squint at their catalogue next time you're in the country. Some could be booty fabbed but I suspect it'd be more practical to buy the majority of it - not least because otherwise you'll never ever ever get round to building you truck!

Next time I'm back in the country, I'm back for good Mr Fridge! Yeeeehaaaa!

Aha! Do they now - I'll check it out, t for the pointer. Anything is better than what I'm finding on fleabay.

Ta, Al.

P.S. I have a truck...?

A normal filter will produce nice air, as long as the incoming air is cool.
I bought a filter from Norgren with everything in it, charcoal and a coalesing filter. I discarded the charcoal element when I replaced the filter some years ago; the cost of replacement filter elements is sometimes more than the filters cost! I bought a large coalescing filter from ebay for my plasma for less than the cost of a new element for the filter on it..

I have a receiver about 6 feet long and 2 foot diam then 30 feet or so of metal tube before the filters. The compressor has finned intercoolers between stages, this produced good enough air to spray.

I ran a large hydrovane road compressor for blasting and water was a real problem. The answer was to cool the air. The coolers we used were from the scrap at an airconditioning place, a pair of coolers was close to a metre cube and we found a large water tank to put them in. the air ran into our unit and then to a pair of the largest 'drip leg drains' norgren made; the bottoms of the drains was left cracked open and a steady stream of water shot out of them. The blasting media stayed dry.

The air conditioning place had loads of the condensors scrap.

Get a modern Ingersol Rand hydrovane compressor - some of the higher spec models some with a dry air function

Or get down to your local HGV breakers and get yourself a truck air dryer, buy yourself a brand new Volvo one and its covered for mechanical failure anywhere in europe for 2 years IIRC

Got a catalogue and price list from these guys recently
http://www.shiremoorcompressors.co.uk/

Has compressors and all the drier bit in there. Makes a nice read.

Steve

15 bar springs to mind, I did check, and found it high enough for what i want, the relief valve i'm using is 10 bar.
edit: this spec sheet for copper pipe rates the pipe itself at 58 bar - well over-spec'd, the fittings will obviously be the weak point.

Soldered fittings will be better than olive/compression, but i don't have a torch and compression joints haven't caused me any major problems, especially as i isolate the pipework at the tanks when not in use. If i don't, small leaks will drain the 300L to atmospheric in about two weeks.

if you look at the photo, the red valve you see was intended to be a water draw off for the vertical pipe, directly beneath the vertical run up to the regulator. I have never drawn off enough water to quantify - maybe a puff of mist in the air.

The air i get is cool, in fact, as it expands at my impact wrench the handle gets too cold to touch, the 200tdi's crank bolt proved that one.

When I start looking at spraying, i will get better filtering, but that'll be after I've moved, so not in the near future.

I'll be interested to see your solution

Al,

I think your options are, in ascending order of DIYness:

1) Buy an oil-free compressor system, as above
2) Buy the relevant industrial add-ons to make your existing setup dry and oilless
3) Use truck/bus bits with their cheap and cheerful driers and dessicant filters (this is what I'd do I think)
4) There's a "new" oil-free compressor in Professional Engineering this week, it's a high speed DC brushless motor with a turbocompressor nailed to one end - you could make something like this? It probably wouldn't be very efficient at the volumes you're asking for though.

Do you want the air for spraying or breathing? It's all going very Moglite...

I used to have trouble with water droplets getting past the drier when using a high pressure spray gun for painting . I was using a portable (13 cfm) compressor, but with our hot weather the drier wasn't really doing a great job. The simple solution was to use a short length of copper pipe (about 1 metre total) wound in a tightish coil that I could connect in series between the compressor outlet and the drier, and submerging the copper coil in a bucket of water. This cooled the air really well and the drier performed faultlessly after that. It was also completely portable like the rest of the equipment (and cheap). I just used ordinary Ryco snap couplings to connect it up.


Paul

Hi guys, thanks for the inputs on this. I've been researching, and today I started getting bits / sticking them together.

I'm looking to run a triple 'Franzinator' with intermediary copper coils, followed by a refrigerated coil and final water seperator / dryer.

A 'Franzinator' is a vertical tubular vessel into which compressed air flows at the mid point, water vapour condenses on the sides and flows down the walls to a drain tap at the base.

All piping will be 22mm copper.

Now for my recent dilemma: I went to the local plumbers supply place today, and they couldn't tell me diddley-squat about the rating of their 22mm copper pipe. Whats more, the pipe is actually cheaper in Homebase!!! They claimed it was because they only use British copper, so the costs were higher... (Do we have any working copper mines???)

Anyway, so, will the homebase stuff, at 16.50 per 3m length be up to it? Any suggestions for cheaper copper pipe?

Any recommendations for the final dryer?

Cheers, Al.

LandymanLuke, can i ask how you connected your compressor to them copper pipes and what fittings were used.

Its a great idea by the way.

Thanks

Gav

they're all just standard plumbing/gas fittings, the valves screw into the tanks, there's flexible hose on the 50L tank, the 300L tank goes straight to 15mm copper after the valve.

so luke, you use a small compressor linked to a big tank, therefore saving about 600quids on buying a big compressor.... how intelligent..

i'll look at my compressor set up tomorrow and post pictures

id very much like to know why you need such dry cool air... mine is always cold and dry, but my 250lt tank cools it well. and its condenses all the water inside, so i have to drain it daily, sometimes i get about 2 pints out of it when ive been spraying.

Don't forget the fridge compressor, that's an important part too I hardly use the 50L compressor.

The problem is of course, you can't run continuously if you're using up an air reserve in a big tank. If you need it to run for a decent period, you need to be within the capacity of the pump. Good plan for small jobs though.

If you're asking me about the need for dry air, its for a plasma cutter - I want to get the best cut quality I can out of it and the air condition is very important, unless you're just lopping bits off in roughly the right place and not too worried about cut angle / kerf / dross etc.

Al.

Al - Jez's compressor is a standard Machine Mart jobby with the default filter / separator and it's used for spraying and plasma cutting with no great problem. Sure a little moisture gets through every so often but adding another standard drier to the setup would sort that if you had a concours paint job to do on something.

I think you may be overcomplicating this (just for a change), try running with what you've got before you decide it's all crap and must be replaced with some vast network of pipes and tanks. Anyone would think you were trying to divert effort form finishing a truck

As I say John - its fine for 'general chopping', but thats not the aim here.

There's nothing very complicated about running the air through a few pipes to sift out the water vapour before you use it, and it makes a big difference with a 'proper' plasma system.

There's no great rush - I'm fine running it as is for now, this is part of the CNC plasma project.

Al.

Considering you've not built that yet to see if you actually need drier air, why worry?

Others have, I do. Its not a question.