Compressor – one big tank vs a few smaller ones
- This topic has 20 replies, 7 voices, and was last updated 13 years, 6 months ago by .
- Posts
As some of you may know, as well as my day job I do a few bits in the evenings at a mates workshop. The main problem I’m having is with the air supply. He owns a small compressor (around 8 CFM) with a 50 litre tank, and I’ve got another small unit, ~10 CFM with 50 litre tank.
When I’m spraying I’ll hook the two tanks together, so my pump works most of the time, with his kicking in when needed. It gives me enough air to run my gun well enough, but because of the high duty cycle and small tanks I get quite a lot of moisture coming through the lines. I’ve done a quick fix by putting a DeVilbiss Whirlwind filter on the bottom of my gun, but I’m looking for a more appropriate solution.
Clearly a big ass compressor with a dryer would be the ideal, but for the small amount of work I do it isn’t financially viable. Now I’ve managed to come across a 100 litre tank that I can have for free, so I’m thinking of the following set up, which should provide a reasonable solution for minimal outlay:
Hook both of the smaller compressors together as I do now, but run the outlet into some hard piping on the wall. This will be copper for maximum cooling effect, and snake back and forth on the wall to give about 20 foot or so, with drains where needed. This would go into the new tank I have, then I’d take a hose from that, through a simple water trap, to the gun.
Does that sound like a workable plan, or have I missed something obvious?
My thinking is that the air should cool pretty well in the hard pipe on its way to the remote tank, which in itself should help to cool and condense the moisture out.
I know it isn’t the ideal solution, but as I say, for the occasional job here and there its cheap, but hopefully effective.
What do you think?
Cheers,
Andy.Sounds like a good solution to me Andy – I’m working on a 1″ copper pipe cooler myself right now. I’ve got about 30′ of 3/4″ copper running into this (adding one more turn tomorrow), then it dumps down into a “T” then to a water trap.
[IMG]http://i862.photobucket.com/albums/ab189/grpA_240/copper_pipe_cooler.jpg[/IMG]
The more storage the better, sounds like a good plan.
Also another easy option would be to source a section of copper coil and solder some ends on it. Drop it in a bucket of ice and run your air through it to cool it. Getting a bag of ice before you spray might get old, but if only using it occasionally it might not be bad. Plus if you use the bucket of ice you have a place to keep your beer close and cold while you paint! :cheers
when air passes through a small opening into a larger air space it condenses – it is noticeably colder that room temperature when you spray your hand with air from the compressor.
I have an 80 gallon….. which is a whole bunch of liters…. ducted into a pair of 20 gallon tanks taken from old dead compressors. by the time the air passes through the 3d tank it is VERY dry. My big main water trap is a few feet after that, and it’s literally dusty in the bowl. nothing ever bleeds out of it. I have a dessicant dryer right before my paint line, just for good measure.
my compressor is only good for 11 CFM, but is good enough for just about everything I need it to do.
Is that a fact of physics? Or just from your experience? I’m just curious, good information. What if it goes through a small opening on to a area that’s same in size like 2 60 gal tanks?
I like the pipe cooler idea, but:
[quote=”ryanbrown999″ post=20464] Plus if you use the bucket of ice you have a place to keep your beer close and cold while you paint! :cheers[/quote]
That’s got to be the best idea yet! :rock[quote=”bobwires” post=20467]I have an 80 gallon….. which is a whole bunch of liters…. ducted into a pair of 20 gallon tanks taken from old dead compressors. [/quote]
It was a picture of your set up that gave me the idea in the first place.Cheers for the replies & ideas guys. I’m sure I can make something work now.
[quote=”sagikun” post=20472]Is that a fact of physics? Or just from your experience? I’m just curious, good information. What if it goes through a small opening on to a area that’s same in size like 2 60 gal tanks?[/quote]
It’s ‘physics’ as taught by my uncle who owned a body shop for a long time. In practice, it is a hard fact. Like I said, after 3 tanks the air is REALLY dry after running all day. I can crack open the valves on the tanks, and tank #3 barely spritzes anything out after a week of use.
I’ve also brought up drying the air going into the compressor head – a coil of copper wire, a single drip leg, and you’ve got some dry air before it even hits the pump.
Yes, it’s part of a Vapor-Compression Cycle like what is found in refrigeration. Compressed air leaves the main tank (similar to expansion valve) into the larger diameter copper tubes which causes flash expansion leading to a cooling effect on the air. Damien
Thanks for the technical explanation Damien, but I look at it with layman’s logic – the air gets hotter when we compress it, so surely it gets colder when it expands 🙂
There may be a further development to this story however.
I’ve almost convinced my mate to buy a bigger compressor that’s up for sale locally. Around 30CFM with a 500 litre tank (~130 US Gallons I think). We’re hoping to house this in an outside store at the back of his premises. Due to the sloping nature of his site the pipework will then come straight up around 20′ to reach inside the main building, where I’ll then put the smaller 100 litre tank and some kind of distribution piping.
That should sort it!
copper isnt cheap these days so i have been toying with the idea of using a domestic central heating rad as a condensor ,run the air in at the top then fit a watertrap the oposit and lower end ,the internal length will be fare longer and the coooling effect far greater plus to degrea it will also act as a reserve tank
the other way is to use an old intercooler off a car or aircon radPaul
Not sure about the car rad or intercooler Paul, as neither are built to take that much pressure really.
Domestic rad might work well though. You’ll basically have a small reservoir/tank with a large surface area, so it might do the trick if it can hold the required pressure. Clearly the same volume of copper pipe would have a greater surface area and thus provide better cooling, but as you say, copper isn’t cheap these days.
Ended up buying a second hand one of these:
[img]http://www.abac-support.co.uk/individualmodels/Beltdrive/B741_24.jpg[/img]
Slow running two stage pump with a 270 litre tank. 10 HP motor, with an FAD of 33 CFM
The air is cooled between the stages, then again afterwards before entering the tank, so ought to help with the CAH issues a bit.
http://www.abac-support.co.uk/individualmodels/Beltdrive/0070NS928,%20B741_270.htm
Just need to get it installed and sort out the plumbing :rock
That’ll do. Now just braze up that 1″ copper pipe and you’re good to go!
I’m actually considering something like the Sealey Fast Fit Air Supply System.
I know of a few people that have used it, and have seen two systems installed and it looks ideal. The push-fit connectors are designed for use with their own nylon pipe, but that can quite easily be substituted for copper. Sealey only offer 15 or 22mm O/D piping, but a similar system includes 28mm O/D too. Those are the three most popular sizes for copper tube over here, which is handy 😉
The main advantage for me is that these systems can be taken apart and reconfigured easily. Ideal since there may be a change of premises coming up, and they can easily be extended/expanded as the need arises. It also includes some very handy water trap Tee pieces, which allow air to pass down the supply drop legs, but not water.
[url=http://www.toolbox.co.uk/link/1/AIR%20RING%20MAIN%20SYSTEM.pdf]LINK[/url]
[quote=”Andy T” post=20611]Not sure about the car rad or intercooler Paul, as neither are built to take that much pressure really.
Domestic rad might work well though. You’ll basically have a small reservoir/tank with a large surface area, so it might do the trick if it can hold the required pressure. Clearly the same volume of copper pipe would have a greater surface area and thus provide better cooling, but as you say, copper isn’t cheap these days.[/quote]
take a look at a lot of compressor aftercooler units ,they are very much the same thing as intercoolers and oil coolers on cars
i would also say that to configure copper pipe to achieve the same lengths and surface area as those involved with a average domestic radiator wouild be a plumbers nightmare especialy a double panel convector, an old rad would also be financialy more viable ,it could also be dropped into a vat of cold water for added effect
im pretty sure my son who is gas safe registered said they should be capable of some 10 BAR plus ,however if fitted post diaphragm regulator you would not require any more than 4CFM for spraying purposes anyway ,as the fitting will be standard BSP and airline compatable it would be an easy enough excersize
- You must be logged in to reply to this topic.