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Looking for your thoughts on a moisture trap made of pipe.

4K views 15 replies 11 participants last post by  Rick_L 
#1 ·
To help eliminate moisture from my air compressor system I'm leaning toward building a moisture trap using copper pipe. I'm not interested in anything plastic like PVC or CPVC, no galvanized, and shying away from black pipe for now. Maybe I'll rethink black pipe but I doubt it.

I'm hoping to tap into the knowledge of you folks who may have already created their own system.

My plan so far is to have a series of vertical pipes like you see in many videos discussing this option, and drain valves installed on the bottom of dirt legs where the moisture should be driven as the air flows downward before turning up into the next vertical pipe.

My questions are more concerning size than anything else, and posted here in no particular order of importance.

Can I limit my vertical pipes to 5' to take advantage of the usual length of a 10' stick of copper, or do they need to be longer?

Is there magic number of lineal feet I should use for these vertical runs?

Which is sufficient without overkill -- 1/2 or 3/4 --- to be sure I'm not encroaching on the available cfm and pressure?

Which size will be the best for eliminating heat from the compressed air and allow the moisture to condense in the pipe? This kinda also gets back to the length of each drop.
 
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#2 · (Edited)
My paint booth is about 80 feet from the compressor in my shop building. I ran 3/4" PVC underground and put a water trap and drain on the lower end. I have a water filter/trap in the paint booth, but have never got any water from that trap. It all drains to the low end of the pipe. The PVC pressure is regulated down from full compressor pressure.

I wounder if your system of pipes would work better if they were tilted just a little off horzontial with the drains at the lower ends. You could use longer runs and have fewer drains. Put a large trap on the low end to collect water so air flow won't push it up the next pipe.
 
#3 · (Edited)
I think you're overthinking this, making it harder than it is.

Just make sure that your horizontal runs of pipe are uphill past the vertical water trap pipe. This lets any condensed moisture drain back into the vertical water trap pipe. Make the water trap pipe the same diameter as the rest of your piping, just because that's easier - no different sizes to buy and no jump size adapters. A longer pipe just makes it so that you can collect more water before dumping it. For most home shops, dumping it once a day or even once a week doesn't require a long pipe.

There used to be a great generic piping diagram on the defunct tptools website. They also sold the black pipe hardware to accomplish it. There's probably other good ones on the web but I can't direct you to one, maybe someone can. Doing it with copper rather than black pipe is probably even better, plastic should work too. It's not the material for this part.
 
#14 ·
There used to be a great generic piping diagram on the defunct tptools website. They also sold the black pipe hardware to accomplish it.
Rick...I found that TP Tools is not so defunct after all :)....Here is a link with a lot of info and piping diagrams: https://www.tptools.com/

 
#4 ·
I agree with what's been posted already, and there's no reason for drains anywhere but at your compressor and wherever you add drops to 'outlets' but I'd add a couple of thoughts.

I followed the 'old Truman Industrial Products' (TIP) guidelines when I set my shop up 40 yrs ago, and followed the same when I did my newest shop 4 yrs ago. As Rick stated, it's a good guideline. If I can find an old TIP catalog, it will have the diagram and guidelines in it and I will post it.

1) Isolate your distribution system (thermally) from your compressor. I used a flexible, steel clad rubber line coming from the compressor (located outside) thru my shop wall. The compressor also has both automatic and manual drains on it (80 gallon horiz with 'old' two stage Ingersoll Rand compressor and a huge electric motor. My compressor was OLD when I bought it from a dying body shop. I put a new tank on it and it's been running the 40+ yrs since!

Compressors will get hot when running. You want the 'warm air' running into your distribution system to 'cool' before you use it to condensie out any water in the air.

2) I used 3/4" ID black iron for all my drops into my shop space, with dryers, regulators, etc coming off those drops horizontally, and the vertical pipe continuing downward to a 'cutoff' valve draining that vertical pipe. I believe the black iron stays relatively cool to help condense out moisture in the pressurized air.

3) To get from one side of the shop to the other, I used 1" ID PVC, keeping the PVC in the attic space (right above my ceiling under insulation). I made sure the closest end to the compressor was ~ 2" lower than the opposite side. The larger diameter PVC minimizes the pressure drop. The use of PVC limits thermal conductance across to the black iron pipes on the other side of the shop.

If you try to keep the black iron pipe 'cool' (relatively), then any water in the air will condense more readily and run to your drains.
 
#5 ·
With a nod to those with more technical knowledge than I about this subject, I'll let you know how I put mine together just a couple of months ago since it seems to be on point with your question. I made a series of three legs of 1/2" copper (Type L), 4' per leg (for no other reason than because a 10' joint would yield two 4' pieces plus some extra for the short cross legs and other misc short pieces) and put a ball valve at the bottom of each leg. I realize that a true dirt leg would normally need to be on the downwind side of the leg...but that's not how it worked out. The last up leg leads to a regulator/auto drain drier, joined with a union on either side, from there up at a severe angle to feed the shop and other drops. The main run around the shop continues to fall backwards toward the main drier - the two main shop drop feeds both have their own regulator/driers.
Gas compressor Machine Gas Cylinder Boiler

Wood Floor Flooring

Two of these pictures apparently decided to load 90* out of orientation - you'll get the idea, though. The line from the compressor tank is a high pressure rubber hydraulic line with a swivel end that travels through a 3/4" ball valve, straight down and curving toward the beginning of the copper run to the cooling lines, running downward to the first ball drain valve.
Electrical wiring Technology Wire Cable

My experience so far - this has been an unusually humid summer. I leave the tank valve closed and the compressor switch off when not in the shop. Before opening that valve to the system I open the drain valve at the bottom of the tank - this removes 98% of the moisture that was created during the previous use. I begin to slowly charge the system from the main ball valve, and immediately cycle the ball valves at the bottom of the cooling lines - usually get a small splash of water from the first valve, sometimes a little spit out of the second valve, and almost never anything from the third valve. Again, I open the system slowly to give any moisture a chance to exit those valves rather than blow past them. Have rarely seen any moisture from the drip valve on the drier. This is a set up that was 'planned', but not really engineered, so others might have suggestions to improve it; but I have no complaint whatsoever about how it's performing so far. JR
 
#8 ·
With a nod to those with more technical knowledge than I about this subject, I'll let you know how I put mine together just a couple of months ago since it seems to be on point with your question. I made a series of three legs of 1/2" copper (Type L), 4' per leg
That looks like a pretty fancy/efficient cooler/trap setup. It also looks like the same regulator/filter/separator that I have. Inexpensive but it works great.

Last time I emptied my clear trap (I forgot about it for a LONG time) it had maybe a tablespoon or so of water in it and an oily residue. I'm guessing my antique compressor is using a little oil, however the oil level has not changed in 5 years.
 
#7 ·
Way overkill bud. I built my system similar to the TP Tools diagram. I ran 3/4" pipe for the main trunk with 1/2" pipe drops and a "clean out" valve at each drop. The system was installed in '06. I will crack open the clean outs every so often, when I think about it... Very rarely does any thing come out but air.
The main line on my system is about 40' long. The only drops I get ANY moisture out of are the two drops closest to the compressor, under 20'. The others never blow water.
This is just 40' of black pipe, nothing special and I have no issues with water. I was spraying fenders the last two evenings and the regulator/filter was dry after almost 45 minutes of spraying...
Mark
 
#9 ·
Thanks for all your suggestions.

After looking through a lot of threads even remotely discussing this subject I did run across the latest version of the tptools diagram, as well as photos someone posted of their soldered copper version of the risers that diagram uses to create individual drops rom the main pipe line.

My garage shop air consists of two smaller compressors tied together. One is only an 8-gallon unit and I still move it where I need it on my property depending on the small job I need to handle -- like an air nailer. When I want to use air tools in my garage I hook them together feeding one into the other with quick connect hoses and have one discharge for as much volume as this mickey mouse system will create. So far it works for what I need and at minimal expense, but does seem to create a significant amount of moisture. I haven't done any yet, but the only painting I plan to do will be epoxy primer.

My garage and where these compressors (and electric feed) are situated looks very much like 55Madman' shop --- tucked into the corner by the garage door.
I don't have the need to run lengths of pipe around my garage to provide numerous drops that would also serve to remove moisture and heat. So far all my tasks only involved a 50' length of rubber air hose, and I could probably get by with a shorter hose in many instances to help eliminate some of the expected pressure drop.

The dehumidifying system I was considering is very much like 55Madman's, and I plan to include a regulator plus oil and moisture filters at the end of the copper.
I'd like to get rid of as much moisture as I can before I overwork the moisture filter.
I noticed 55Madman recognized the dirt legs would probably be best installed at the bottom of the down-drops which I believe would take advantage of the velocity of moving air to force moisture from the air, as well as the better method for condensed moisture to drain to the dirt leg. I'm considering use of 45's instead of 90's on the lower horizontal segments to avoid any possibility of moisture lying on a virtually flat section. Since this will all be from scratch, might as well build the better mouse trap.
He also had the same consideration I had -- getting the most of a 10' stick of copper without involving additional couplings.

I'm wondering if 1/2" would be better than 3/4?
Obviously cheaper for all components involved, and would the smaller diameter force the air to travel at more velocity to expel moisture into the dirt legs?
Probably minimal performance difference at best when discussing velocity to forcefully expel moisture.....

But ..... 55Madman -- has the 1/2" provided sufficient cfm and pressure from your compressor, or has it caused a noticeable restriction where 3/4 would have been a better choice?

For what it's worth --- speaking with a seasoned plumber he tells me the usual fittings you find available are all the same as M copper -- so if you think this type of dehumidifier is what you want to build there isn't much reason to step up to L copper pipe for presumed extra strength. Weakest link and all that.
 
#10 ·
This installed at air compressor outlet. https://www.harborfreight.com/38-In-Desiccant-Dryer-with-Oil-Removal-Filter-69923.html

This at paint gun https://www.harborfreight.com/disposable-inline-moisture-filter-68224.html These you can use a few times and toss in trash.

Make sure to drain compressor tanks daily of water.

With those you shouldn't get any water, with a paint gun. The desiccant needs to be changed or dried when it turns color.

Cheap, easy, and works just bolt on today and enjoy.


Painting your not going to make that much heat vs say blasting, it may make some water on a humid day but I wouldn't paint anyway if it was that bad. The disscant will work fine for low CFM of a paint gun.

If you need to run more lines 3/8'' is fine line psi/cfm wise with little compressors, 50ft, and painting (not a real big CFM draw anyway). Make sure to check PSI at tool with a gauge and simply adjust pressure reg to get the pressure you want at tool itself you'll get some pressure drop even with short hoses. CFM drop really won't be noticeable unless using a tool that needs alot of CFM like a blaster.
 
#11 · (Edited)
A lot of considerations and options to deal with. As I was pondering all of the issues you highlight, I reached a point to where I had to admit I was over thinking it, and needed to just put something together and get back to work - realizing what I was going to put together was way better than average and most likely as good as I'll ever need. Here are my thoughts on your comments:

As I'd said before, the overwhelming majority of condensation is created within the compressor tank. I'd always thought one wants a larger tank for additional volume, which is absolutely true; but I hadn't considered that a larger tank provides more opportunity to cool the compressed air, and condense the moisture. This became obvious to me as the more the compressor runs, the more the tank drain expels...exponentially more. The cooling drops also expel more, but only slightly more...the tank is doing the bulk of the work. When I'm at the blasting cabinet for example (or using a d/a, paint gun, whatever) it seems the cooling legs do help, but the air is moving so fast through them the regulator/driers wind up doing more. Perhaps an argument for moving the cooling legs several feet downstream; or going to 3/4" or larger pipe up to them... the options begin to boggle the brain. But here's my conclusion - with a blast cabinet about 15' downstream of the legs, on the hottest and most humid day, I have had no perceptible presence of moisture clogging the flow of media...so - success. I don't use a spray gun to paint very often, and that drop is 30-odd feet downstream on another run (more cooling opportunity), with another regulator/drier, I'd still use one of the point of use driers at the gun - cheap insurance.

Other thoughts - remember that where air flow and restrictions are concerned - your most common one is the quick disconnects. Larger diameter piping helps overall, but your flow will be subject to the capacity of any quick connector. As in the case of hooking two compressors together...you increase volume and perhaps pressure, but you put a restriction right in the middle of it all. Will it make a real world difference? Depends on what tool you're using. As for using rubber hose, just keep in mind that a good rubber hose is essential, but it is also an insulator. Best practice is to get the moisture out before it gets to the hose. I use a 50', 25', and a 10', with the shortest one to do the job being my choice. Less to walk/trip over, and I'm surprised how little I use the longer ones. My dirt legs are not on the ideal side...I think that was the product of doing the soldering at midnight or later. Decided to just go with it, and in practice doesn't seem to have made a significant difference. I'd do it different if doing again. I decided that 45's instead of 90's was, indeed, overkill for an amateur shop and increased the complexity of the design and number of joints I'd have to sweat together. Same thoughts as 1/2 vs 3/4...overkill for what I was going to need. L vs M - I had the same thought - the fittings are the same, so what's the advantage. Also, what does the effect of thicker walls have on heat migration to the exterior of the pipe...again, I reached the point of overthinking and just grabbed the thicker...was only a couple of bucks more. Good luck putting your system together; I'd be willing to bet you'll be very satisfied with what you wind up with. JR
 
#12 ·

Compressed air air line installation guides
1 - 1 inch pitch down for each 10 feet of horizontal run
2 - take off lines are taken of the top of the run
3 - a down run at end of each run with shut off valve
to exhaust water out of the system
4 - a short run below air hose quick connect with shut off
valve to exhaust water out of vertical down run
5 - At the output of the compressor tank
- a shut off valve
- a tee
- a down run with shut off valve
this will help to prevent run back of water into the compressor tank
and you can exhaust water out of that vertical line
 
#13 ·
My thanks to all you folks for your input.
You've given me a lot to think about, and certainly some points that I overlooked as I hatched this idea.

I'm certainly learning something new every day, always finding something new to research before I walk a path, and reminding myself of one of my favorite phrases, "You don't know what you don't know."

As I read the list of contributors to this thread I recognize many as folks who also contributed to many other threads that have served me well as I slowly (very slowly) walk myself through this long overdue project of bringing my 57 back to life.

Thanks for routinely looking at this forum and providing your opinions.
 
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