Thread: Inline air filters

Originally Posted by WelderMick

Hi guys, I've been looking around on line for air line filters to trap water/oil between my air compressor and plasma cutter. If anyone has any tips for online suppliers, or some suggestions for a home-made model it would be greatly appreciated.
Thanks
- Mick

This is what I use. DIY out of water pipe.

Air micro die grinder

Works excellently.

Lowers the dew point, traps about 95% of moisture, and then goes into a regular Schrader drier/trap which basically has next to nothing in it.

It's just a cut down version of water trap/pipe network that most garages use - same principle.

Rob

Nice one Rob, I can see how that would very effective. I suppose there's no reason that a multiple shorter pipes wouldn't work either (but would cost more with more drain taps and fittings). I was hoping for something a bit more compact, but I certainly like the simplicity of it.

Good one Rob, just what I have been looking for

the suggestion above is probably the cheapest and easiest option...

the professional options in order of increasing effectiveness are:
1. air cooler followed by water trap and coalescing filter (basically whats proposed above)
2. consumable desicant dryer (as per http://www.airless.com.au%2FPDF%2FSp...e%25202012.pdf page 43 & 44)
3. refrigerated dryer
4. regenerating desiccant dryer

I have been toying with the idea of building a consumable desiccant dryer but at $200 for a 20kg bag of dessicant i haven't been able to justify it yet. The other idea was using and old bar fridge to make a refigerated dryer... this is probably a better as I have a fridge thats just hanging around getting in the way.

I'm sure Rob has linked that site before......but i know how hard it is to get the search terms right!

When i was a cabinetmaker we had copper air lines throughout the shed, and every outlet had a trap just like that. The lines came down the walls, the outlets where at maybe 1500 high (with reg, water trap etc) and then they continued to about 500mm off the floor ending in a stop cock. Of course one of the apprentices jobs was to empty these every week. It was amazing just how much water came out sometimes.

Which is better for removing the heat, copper piping or standard galv water piping as shown in the link?

What's the desiccant used in the consumable desiccant systems???

Copper has better heat conduction characteristics

Sillica gel is usually used as a desicant (can be re-generated)

Michael

Originally Posted by WelderMick

Nice one Rob, I was hoping for something a bit more compact, but I certainly like the simplicity of it.

You can easily go more compact.

Instead of running through cold pipe, go to the wreckers and get the air conditioning condensor out of a car (that's the unit in front of the car radiator) and plumb through that.

They are rated at over 200 PSI. Cut off the connectors and use compression fittings or braze to copper pipe. Orient the condensor so that the tubes are horizontal to allow water condensate to flow through the unit.

You still need to run the outlet into a large cylinder type water trap with a drain cock before going to a commercial filter.

You don't need a fan on the condensor as convection air circulation will be enough to dissipate heat.

I could have gone this way, but I didn't have a condensor handy at the time.

Either method works well.

Rob

Hi Mick,

Where is your pressure reg?
I've only even seen tiny inline water traps.

Or are you just talking about another one of these?
AIR FILTER REGULATOR control unit[WATER TRAP]NEW 150 psi | eBay

Stuart

I needed quite dry air for powder coating and went through this process a while back. Instead of placing the condensor on the outlet of the receiver tank, it will work far more effectively if it's placed between the compressor head and the receiver. The idea is to get the walls of the pipe below the dew point of the air passing through it, and this is more easily done while the air is hot. I originally wanted to use an air conditioning condensor as it would have looked neater, but in practice after trying a few I found the tubes extremely difficult to silver solder. In the end I used a coil of copper from the scrap dealer. Bunnings sells the same, but not at the same price!



After the copper coil I modified a very cheap regulator I had lying around. I took the regulating part out (obviously you don't want that between the head and the tank) as all I wanted was the water trap. What you want is a self-draining water trap, otherwise it will fill too quickly. When the unloading valve opens at the end of the compressor cycle the water trap drains and dumps the water and oil into an ice-cream container under it, just to stop it making a mess. The copper coil is stiff enough to be self-supporting, and the air path such that it is continuously down so any water will run in to the trap. I just used a standard plumbing hose to run up to the receiver as it was rated for these pressures and the air is by then quite cool ... and I just happened to have it already! A rigid pipe would probably be better if you wanted the whole lot to be better self supporting. The water traps as most people install them BTW are completely useless. All they will do is somewhat prevent condensed water in the lines being blown through to the gun or whatever is at the end of the line (and why they should be up at the end of the line, and again not where most people put them on the outlet of the compressor. When I had one installed in line I didn't ever collect a single drop of water out of it!

In use it is very VERY effective, and a significant amount of water is collected on each cycle. The top if the coil is too hot to touch, but the bottom quite cool, even when running continuously. The reason it's left as a coil (it's supposed to be a cone in fact) is to spin the air against the walls of the tube as it passes down. I had intended to weld up a supporting frame and hang a fan pointed up so the air passes through the cone and wired in parallel to the compressor motor, but in practice haven't found it necessary. It all looks a little bit of a bodge at present as the whole lot will be moved to a completely different location, and the compressor mounted in a sound-proof enclosure. I will probably mount the coil properly outside the enclosure then. It's a classic case of making something to see if it will work, and then going back to the reason it was made in the first place! I have no idea why that crappy plastic air coil is plugged in, and didn't know it was until looking at the photo myself, it would be going up to the sandblasting cabinet though. The main outlet is out of shot and goes to my existing plumbed air, but as I say the whole lot will be changed around when I get some more time.

If you want REALLY dry air, I have a water filter housing with 1/2" fittings that is filled with desiccant. However I can't say how well it works as I haven't even had a need to use it (the air is currently very dry) and it's just sitting there until the rest of the workshop is plumbed properly with irrigation pipe (a cheaper way to buy air line BTW, it's the same type of plastic). Using desiccant as a primary means of water removal however is not recommended. The amount of moisture in the air is quite surprising, and you'd be continually battling to recharge the desiccant as it was overwhelmed with moisture. I'll eventually put mine in as it was cheap to buy and will also act as a filter.

Hopefully that's of some use as I found it works much better than I could have ever hoped.

Pete

And where exactly does the alcohol come out

Good write up Pete.......but can we see some pics please?

I agree Rob, just tell me where the 12yo single malt comes out and I'm there......

Originally Posted by Ueee

Good write up Pete.......but can we see some pics please?

Sorry I don't understand? I posted a picture, is it not working?