Thread: Inline air filters

The pic works for me. Excellent idea, thanks for that.
Kryn

I'm not sure what to suggest regarding the blue square, not if it's being seen by some people. I'm hosting the image on Photobucket, so perhaps it's being blocked?

Speaking of stills, yes it's precisely the same principle, except here we're condensing the water out of the hot compressed air instead of the alcohol out of the hot still gas.

Pete

The picture works fine for me Pete.

Heavy duty coolers/condensors like the DIY's shown make a huge difference.

The whole guts of the matter is that you must cool the charge to below dew point for any trap to be effective and that's precisely what these coolers do.

No more water streams out of air tools and perfect spraying conditions.

Definitely the way to go.

Rob

Try the link -

http://i738.photobucket.com/albums/x...essor/file.jpg

Nev

Originally Posted by gallegos

...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.

Thanks for the info - I was wondering what dessicant might cost. Surely smaller lots are available though? particularly if it can be dried and reused?

Originally Posted by Stustoys

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

Hi Stuart, there's the actual regulator integrated with the compressor (see this little thread about the purchase: https://www.woodworkforums.com/f65/vi...8/#post1593621), then it goes to my air hose then a little water trap/regulator thing like the link you posted immediately upstream of the plasma cutter (which I realise is really just a last line of defence). Given how much air the plasma uses (and likely volume of accompanying water), I thought the small in line filters would either a) be useless or b) be really useless. But obviously it would be great if they did work. I haven't got back to the shed to have a really good look at the plumbing of the compressor - I'm hoping that it's easy enough to intercept the air whereever I want.

Originally Posted by Pete F

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

Pete, that's great info - thanks. Have you got a thread on this somewhere? What you describe certainly make sense, and I like the idea of having something like that self-contained on the compressor. I think something like this is what I'm going to aim for. Your 1st photo came out fine for me. Could you provide a bit more detail though - is it 1/2" copper tube? What length do you reckon it is and do you reckon a shorter length would do the job (i.e. where in the coil does it get back to room temperature?). The idea of the counter current fan would probably be more of a requirement if the hot part of the coil was at the bottom, but as you have it, it is pretty much ideal. I'm guessing the cone idea is related to a cyclonic filter - but my understanding is that would only be relevant if there were two outlets (water out the bottom, air out the top).
I've no idea about plumbing fittings - could you give some details on what you used and if they're readily available?
Thanks
- Mick

Originally Posted by WelderMick

Pete, that's great info - thanks. Have you got a thread on this somewhere? What you describe certainly make sense, and I like the idea of having something like that self-contained on the compressor. I think something like this is what I'm going to aim for. Your 1st photo came out fine for me. Could you provide a bit more detail though - is it 1/2" copper tube? What length do you reckon it is and do you reckon a shorter length would do the job (i.e. where in the coil does it get back to room temperature?). The idea of the counter current fan would probably be more of a requirement if the hot part of the coil was at the bottom, but as you have it, it is pretty much ideal. I'm guessing the cone idea is related to a cyclonic filter - but my understanding is that would only be relevant if there were two outlets (water out the bottom, air out the top).
I've no idea about plumbing fittings - could you give some details on what you used and if they're readily available?
Thanks
- Mick

G'day Mick, no this is the only time I've posted regarding this as far as I recall anyway.

Yes it's 1/2", you can just treat the whole lot as if you're doing a dodgy plumbing job on the house Just make sure your compressor fittings are indeed 1/2" and simply take it from there.

I'm not sure how long it is, but basically the longer the better (within reason). As mentioned, the bottom part remains relatively cool, so it will still be working. If the coil was to heat up too much it would lose efficiency in extracting the water. I saw some copper coils that looked similar being sold in Bunnings, but didn't take much notice of how long they were. I'd say it approaches room temperature around the bottom 1/4 or so. You could make up a smaller heat exchanger setup if you worked out some way to put it in a bucket of water (preferably cold or iced if it was a critical job you were doing), but the issue with that is getting the outlet out of the bucket without running it against gravity and of course eventually the water in the bucket would heat up.

You wouldn't want the hot air coming in the bottom, as mentioned you want to keep the air and water going in the same direction, and preferably following gravity. Yes you're correct about the cyclonic action, why I mentioned spinning it against the walls. It doesn't matter that the water and air are coming out the same outlet, the principle is still the same.

Hope that helps.

Pete

thanks Pete - I'll have a good look at my compressor tomorrow and work out a plan.

The pic has appeared for me now

I would have to say you have 10m or so of pipe there, at a guess. Make sure you have a drink or 2 before going to Bunnies Mick.....the price will hurt.

Pete, is that a flexible water pipe, the braided type, you have going from the water trap to the tank?
I think i have some pipe somewhere......something to add to the "round toit" list.

Originally Posted by Ueee

Make sure you have a drink or 2 before going to Bunnies Mick.....the price will hurt.

Looks like $119 from the big B. Copper Annealed Coil 12.70odx0.91wt 18m - Bunnings Warehouse. I'll have a hunt around on price, but at least it's available!

Originally Posted by Ueee

Pete, is that a flexible water pipe, the braided type, you have going from the water trap to the tank?
I think i have some pipe somewhere......something to add to the "round toit" list.

Yes it is.

IIRC the price in Bunnings was around the $100 mark. Not cheap, and I happened to find this coil at the scrap metal dealer, I couldn't believe my luck. However compared to a refrigerated air drier it was peanuts.

Pete

hi Pete F, in your post above with the picture of the cooling coil, how would you fit this for a direct drive compressor?

Alos, can you please post a pic of how you connected it for your belt drive unit?

The consumable desicant ive seen has been called dry-o-lite. I think its some sort of alkalia salt tablet (they dont say what) that dissolves and is consumed as it works. Its different to the normal desicant which needs to be heat regenerated when its saturated. It seems a bit easier than having to work out when the desicant is worn out and regenerate it... i guess this might not be a big deal on a small scale.

An aftercooler is installed first on any of these systems to get the air down to room temp and get out most of the water initially but while the air isnt full of water after this it will still be 100% humidity so more water will come out if it gets any cooler like say at an operating air tool or overnight. the final desiccant or refrigerant stage pulls the humidity level lower (reduced the dew point) so this cant happen. guess it comes down to how dry you need the air in the end whether its worth going this final step.

Dengy, sorry I have no idea as to how direct drive compressors are normally configured as I've never really looked closely at one. On this compressor there was a short pipe with some aluminium radiator fins on it that connected the head unit to the receiver tank. I just replaced that pipe with the coil as shown.

Originally Posted by gallegos

The consumable desicant ive seen has been called dry-o-lite. I think its some sort of alkalia salt tablet (they dont say what) that dissolves and is consumed as it works. Its different to the normal desicant which needs to be heat regenerated when its saturated. It seems a bit easier than having to work out when the desicant is worn out and regenerate it... i guess this might not be a big deal on a small scale.

An aftercooler is installed first on any of these systems to get the air down to room temp and get out most of the water initially but while the air isnt full of water after this it will still be 100% humidity so more water will come out if it gets any cooler like say at an operating air tool or overnight. the final desiccant or refrigerant stage pulls the humidity level lower (reduced the dew point) so this cant happen. guess it comes down to how dry you need the air in the end whether its worth going this final step.

The desiccant I've used that is consumable was obtained from hardware stores and I think even supermarkets. One brand name is Damp Rid if I recall correctly, but I know there are others, designed for use around the house. However I didn't like them and I'm also not sure how they would go in this type use. The desiccant I have is blue and turns pink when it's saturated so it's pretty obvious when it's time to recharge it. To recharge pop it in a low temperature oven to dry it out. In a past life when working in marine electronics some of the sensitive equipment would have desiccant capsules built in to them. I didn't have an oven at work, so I'd just rig up a cardboard box with a heat gun on low setting to dry them out. Super agricultural, but hey it worked. As far as I'm aware there's no limit on how often they can be recharged.

I'm not sure I follow you regarding still being at 100% humidity. Once compressed, the amount of water within the air then fixed, varying on any particular day, as is the pressure, it becomes a closed system so the humidity (ie saturation point) is then dependent on the temperature of the air. However even at 100% humidity, there is no issue with the air, it's when it drops below its saturation point (ie the water condenses out) that issues may arise. A dribble of water from an airtool may just be annoying, and not do the tool any good, a dribble of water from a spray gun can spell disaster. You're quite right however, in cold conditions the air MAY still drop below it's saturation point, but in all honesty I have never seen any evidence of water at the end of my spray guns, powder coating guns, or air tools. It must be remembered that the the air starts and finishes at roughly the same temperature. So assuming it's raining and 100% humidity, the compressor takes that air and compresses it, in the process raising the temperature. While it's still hot you pull a heap of water out of it by running it against a relatively cold surface (the walls of a copper pipe), it cools in the pipe, in the tank, lines etc back to ambient temperature. However clearly if it went "in" to the system at 100% humidity and a heap of water was pulled out of it, at the same temperature on the way out it must be considerably below 100%. Hopefully that all makes sense? About the only scenario I could imagine where you may see water in your lines with an arrangement such as I described would be if it was a hot and humid day and you shut the system down. During the night the temperature dropped below the saturation point of the air remaining in the lines. When you first started the following day that water could be pushed out. However it is considered good practice to always have your lines running "uphill" as they leave the tank or a water trap. You then put a drop in wherever you need it but don't tap the drop at the very bottom. Any water in the lines either runs back to the tank at night (or preferably a water trap) or falls to the bottom of the drop where you can drain it off periodically.

As mentioned previously, I have a couple of jars of desiccant and a water filter holder sitting on my bench, and it would take only minutes to plumb it in. Yet I've never seen a need. Of course I will eventually, why not, Murphy's law will be the first time I see water coming out of my gun will be on a critical job, but so far so good.

Pete

Originally Posted by Pete F

The desiccant I've used that is consumable was obtained from hardware stores and I think even supermarkets. One brand name is Damp Rid if I recall correctly, but I know there are others, designed for use around the house. However I didn't like them and I'm also not sure how they would go in this type use. The desiccant I have is blue and turns pink when it's saturated so it's pretty obvious when it's time to recharge it.

Yeah, I've seen that damp rid stuff around, but my preference would definitely be for the rechargeable gel. My plan is to rig up the copper pipe idea between the compressor and the tank and continuous drain point as you've shown, then have a dessicant filled filter at the other end of the hose. They say for plasma that the drier the air is, the better and I can see no downside to using the dessicant apart from needing to recharge a batch every now and then.
I've still got to get out to the shed (a rented one about 10 minutes away now), to have a good look at what I've got to deal with in terms of fittings, etc.
- Mick