Issues with air plumbing and filtering options

[pierre]

I ran copper pipe in my garage before I found this site and started to learn the right way to do things.

I ran my drops with a T straight down from the main top line, not the up and over which I gathered is "proper". I still put a drip leg at the bottom, and the hose is T'd to the side. Should I really go through the hassle of correcting it? I don't get any water out of the drip legs (from either one of the 3 drops) so I'm not sure if there's any advantage in changing the setup.

The compressor is a Quincy QT-5 with a home-made aftercooler. The output pipe to the tank is at ambient even if the pump runs for several minutes continuously. From the tank I have a coarse filter / water separator, the regulator, then a motorguard TP style filter. From there it rises up vertically to the main pipe then to the rest of the drops around the walls. It's just me, I only use one drop at a time.

I'm having a problem with moisture, especially on hot (90+F) days. It only comes out of the tool, the drip legs are dry. That's why I think individual "point of use" filters probably won't help any. Is my only other option a desiccant or refrigerated dryer? Desiccant at the beginning of the line should protect all the drops against moisture right?

I actually have a sharpe 3 stage desiccant system made for paint guns - I just hate the thought of using it because the desiccant stage runs the air through what looks to be a 1/4" tube that is even more restrictive because there is a screen at the end of it. I hate knowing I'll have to turn the regulator up to overcome this restriction and waste compressor output. I seriously doubt its 30cfm rating with the way its constructed. Unless I can find another one cheap or maybe a DIY desiccant container with bigger lines...

 

[akdiesel]

Being that you already used copper and have the "T's" in place it would be fairly easy to go over the top as you mentioned with just a little extra tubing added.
I for one have the same set up you have now only it is stainless. I don't have any water issues, so I don't think the two different metals have that much of difference.
What I do have is a secondary knockout drum down stream of the compressor tank and before the main distribution header. My theroy is that this helps to aid in the JT factor and droping out any liquid before it gets to the lines.
I have seen both set ups (over the top and off the bottom of the headers)with no water in either one, and that is because of desicant system and then an air receiver. I feel it is better to get the water issues taken care of at the start of the run.
Keep in mind also that you will want to keep the air lines away from hot areas. The heat can conduct to the air lines and then cool off down the line and make water droplets.

 

[tcianci]

I know we would all like to have the perfect air system. You didn't mention the type of tools you were running. It sounds like you have a good setup for painting and if you are using HVLP guns and they work well, then your Sharpe desiccant system must be capable of significant volume for the gun. Some guns use more air than an impact wrench! Having some moisture come out of the tool exhaust is not exactly the end of the world. I have seen well lubed air tools run for years on some less than perfect shop air. While you are correct in your observation of the up-and-over style for your air take-off points, if you are not seeing any water in the drip legs, I wouldn't worry about it. It may simply be that you have some moisture in the air being supplied to the tool and it is finally cool enough for it to condense only at the tool it self.

 

[pierre]

Many thanks for the responses!

I use an impact, die grinder, DA, plasma, probably soon to be ratchet and hammer/chisel. Don't paint, don't plan on it either.

Your right, some moisture isn't the end of the world, it just got annoying when I was doing some sanding and having the moisture spray onto the piece and then the dust fall on top. Plus, when I fire up the plasma I don't want to worry about it.

The sharpe desiccant system says 30cfm but not at what psi. I remember hooking it up and it caused a 20+psi pressure drop, whereas the current filtering setup I have only causes a 10psi drop (this is testing using a DA at full speed in the air without load, regulating to 90psi). I'll have to hook it up again to see. The desiccant stage /container is a PITA to deal with, bulky and hard to work on. I've seen some people use DIY desiccant driers here but haven't come across any detailed plans.

Let's say I do put a desiccant drier before my first drop - this will protect all drops right since the desiccant physically absorbs the moisture from the air? I don't have to worry about any more temp change the air goes through as it travels through additional pipe? The pipe runs along the walls and ceiling, not next to anything particularly hot or cold. Only outside temp influence will be coming from ambient surroundings. Reason I ask - all the desiccant systems I've seen are Point Of Use, haven't really spotted any "whole system" desiccant driers.

 

[tcianci]

OK, now I understand a little more about how your system works...The reason the desiccant systems you see are all point if use is that desiccant dryers are limited by how much water they can absorb. Typically it doesn't take much water to saturate the material and then it needs to be replaced. The good news about small desiccant dryers it that some of them allow for the material to be changed and the saturated material can be dried out and used again. I had set up a system like that for supplying very dry highly filtered air to a machine that employed a large air bearing. The internal clearances of this bearing were in the tenths of thousandths of an inch. I had a desiccant dryer that had a polycarbonate, see-through housing and the desiccant changed color when it was saturated. I would change out the saturated material with fresh stuff and then dry the old stuff in a microwave and store it in an air tight container till next time. Because my system used a very small volume of air, I finally installed a self purging desiccant dryer. This device consisted of 2 desiccant chambers, the air passed through one chamber and the output from that chamber was routed to both the machine I was supplying and a portion of the air was fed to the other chamber. The desiccant in the other chamber was dried by virtue of the fact that super dry air from the first chamber was passing through it and then just vented. The timing mechanism in the dryer would shift the air flow through electrically controlled valves and then the cycle would begin again with the chambers reversed. This made for a very handy small volume air dryer. You can probably find them on line somewhere and you can see if there is a unit that will meet your air flow and pressure requirements. Typically we use refrigerated dryers for high air volume installations.

 

[kbs2244]

The up and over design assumes a large diameter horizontal run with smaller diameter drops.
This does two things.
It lowers the air speed through the horizontal run.
And it lets you take “dry” air off the top of the pipe because the moisture has fallen out of the air stream and now flows along the bottom of the larger pipe.

If you don’t have the large diameter horizontal run then the air never slows down enough to allow the moisture to fall out of the air stream.

I am guessing this is your problem, since you say you don’t have any moisture in the drip legs.

You need some place for the air stream to slow down.

 

[pierre]

The horizontal run is 3/4, the drip legs / drops are 1/2". The T's are set so 3/4 to the left, 1/2 down, and 3/4 to the right. The last drop at the end uses an elbow that's 3/4 on end and 1/2 the other.

Two of the drops use 3/8" rubber hose, the third is a 1/4" polyurethane coil hose.

That being said, if I'm not getting moisture in the drip leg then the up and over approach wouldn't make a difference if I follow your logic correctly right kbs2244?

tcianci, that self drying system sounds nifty, but doesn't that mean a portion of the air is wasted? Also sounds expensive, unless I happen to fall upon a "steal of a deal" type of sale. I'm trying to get the most useable air out of this that I can. I don't mind drying desiccant. The sharpe system does allow for this, its not cartridge based. Problem is, the internal 1/4" tube is about 2 feet long, with a screen at the bottom, dropping flow.

Any other examples of DIY desiccant driers here with detailed assembly pix? I found Vicegrips.

 

[tcianci]

Well it is "wasted" in some respect but it does go to drying the air out. You will be consuming some sort of energy in either refrigerating the air to condense the moisture out of it or using some sort of heat to dry out your dessicant. At least the flip-flop dryer is hands off. I can't remember what I paid for it or the volume it was rated for either, but then again, I can't remember lots of things!

 

[Jeepguy]

your concern with the sharpe dryers 1/4" inlet tube is silly, 200+ cfm desicant dryers use small inlets and outlets with about 5 psi pressure drop and zero volume restriction. restiction through filters should be addressed at linlet with a regulator, plus, pressure drop through a filter is no different than through a 30' section of 3/8" hose you have hooked up to your tool.

the only problem with desiccant dryers is their inlet temperature limit. which means you need about 30' of radiant cooling pipe before you can filter the air. most cases there isnt enough room to do that and still have the dryer effect the entire piping system.

the bigger question is why are you getting moisture in your tool, but not your drip leg? (unless i am just missing the point on your description) But Yes, point of use filters will absolutely catch that moisture. especially if it is already condensed. and if its not already condensed you can go with a .001 micron coalescing filter at your points of use to catch the water vapors.

 

[pierre]

Jeepguy,

With the after cooler between the pump and tank, the air going into the tank is at ambient. The sharpe manual lists the 6760 desiccant stage at max temp of 150F, so the air temp is not a problem.

When I had the full sharpe 6760 setup (5 micron 1st stage water separator, 0.01 micron 2nd stage coalescing, 3rd stage desiccant, then regulator) hooked up between the tank and copper plumbing, the pressure drop was 15-20 psi. With my current setup (milton 1/2" water seperator, 1/2" regulator, then motorguard filter) the pressure drop was 10psi. That's 10 psi difference of air "saved" by not going through the sharpe desiccant. I'm measuring this by setting the regulator, using my DA at full speed w/o load, then watching the regulator gauge. Maybe I'm being a bit vain, but 10 extra psi percentage wise is a pretty big chunk seeing as the goal is 90.

You are correct, with current setup I'm getting moisture out of the die grinder exhaust but not on the drip leg for that drop. This was on the last drop of the chain as well, some 40-50ft of 3/4" pipe away from the compressor). I was a bit surprised too. This was on a hot (90F?) day. Only explanation is there was still vapor in the air that the aftercooler, seperator and motor guard filter didn't drop out.

The problem with the desiccant stage of the sharpe filter isn't the inlet or outlet, those are 3/4" reduced to 3/8" for the regulator. The problem is the tube (18-24" ?) inside the unit is skinny. I believe if I had a desiccant can that was more free flowing, the extra 10psi difference could be made up for. This is a residential 2 car garage. Something like 20x20? I put in 3 drops because I didn't want hose all over or to use reels - 2 of my hoses are about 10ft 3/8, the other is a 1/4" poly coil hose for the smaller jobs. That's the one I was using with the grinder.

 

[Jeepguy]

I am familiar with that sharpe unit, the pressure drop shouldnt be that much through those 3 stages. although those are made to be mounted inside paint booths and regulated down to about 40 psi on the outlet (so most people wouldnt notice the drop), and not meant to supply treated air to an entire system.

there are a few options of in line desiccant "torpedo" type dryers. Beach being the largest maker of them, pretty much just a two piece canister, with a desiccant pack in the middle. they are full flow usually 1/2" inlet/outlet. Or you can always just remove the prefilters from that sharpe unit, and put that inline by itself, though you do run a desiccant carryover issue.

the other thing is you could just spend a little $ (still pretty expensive) and get a refrigerated dryer. since you have an after cooler you wont need the really expensive high inlet temp dryer, just a standard refrige.

sorry for the rambling, i do this all day at work.

 

[pierre]

although those are made to be mounted inside paint booths and regulated down to about 40 psi on the outlet (so most people wouldnt notice the drop), and not meant to supply treated air to an entire system.

A-ha! that could explain its behavior. I will try the desiccant stage on it's own to see what will happen. There shouldn't be any carryover issues - the air is forced through the desiccant, then a bronze filtering element before it enters the tube and exits the canister.

Don't be sorry! Glad your willing to share your thoughts & time. I've started investigating refrigerated dryers, perhaps even used. I'll also look into the "Beach" brand desiccant cans.

 

[Jeepguy]

no problem, glad i could help, if i actually helped at all.