"Decent" compressor water seperator - Woodworking Talk - Woodworkers Forum
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post #1 of 18 Old 10-07-2017, 08:55 PM Thread Starter
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"Decent" compressor water seperator

I just got a desiccant filter for spraying. It works great, but replacement filters are expensive, so I'd like to put a separator on the compressor to reduce the amount of a water that the desiccant filter has to remove to lengthen the life of the filter element. I don't think it has to be killer, just something to capture the initial water (and oil)

Any suggestions?
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post #2 of 18 Old 10-07-2017, 09:16 PM
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I don't use a separator at all. I just open the drain on the compressor tank a little so it drains continuously. Every separator I've ever used let a little water through. Draining the tank seems to do just as well.
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post #3 of 18 Old 10-07-2017, 10:42 PM
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Originally Posted by Steve Neul View Post
I don't use a separator at all. I just open the drain on the compressor tank a little so it drains continuously. Every separator I've ever used let a little water through. Draining the tank seems to do just as well.
I thought I was the only one that did that keeps your tank from rusting also.

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post #4 of 18 Old 10-08-2017, 09:44 AM
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I have one of these -

http://www.eastwood.com/devilbiss-ai...SABEgLBwPD_BwE

I mounted it to a cheap hand truck so it can be moved around the shop. I run full compressor pressure to it and use the regulator that's on the filter.



Note that the hose between the tank and filter is an important detail. Air right from the compressor is hot, and hot air can hold a lot of moisture. The hose gives the air time to cool down so the water condenses, making the water separation much more efficient. On really humid days I'll coil the hose in a cooler with ice.

Dave in CT, USA
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post #5 of 18 Old 10-08-2017, 11:29 AM
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Some people here have hit on important steps in getting good air. But first relates to compressor sizing. You need a bigger compressor CFM wise than your biggest use, double is a good starting point. Reason: reciprocating compressors are not designed to operate continuously. The high temperatures they reach that way will cause degrade of the oil and result in deposits that shorten the life of the compressor. Don't judge a compressor by it's HP or tank size! CFM should be stated at 90 psi, industry standard. There are a lot of "cheater" 5 hp compressors sold. It's air output you are interested in, not "hp".
Since air is heated when compressed, it can hold more water vapor. As that air cools the water vapor condenses and puts that water into your tools. Water damages almost every kind of tool and is especially bad when spraying finish. So after the compressor you need to cool the air and then separate the water. Air to air coolers are a good first step. You can buy one or make a reasonable one from fin-tube elements made for heating with a boiler, & a fan. Provide a slope and a drain at the bottom. Next is some way to remove the remaining water vapor. You can make a desiccant drier out of a piece of pipe, some SS steel screen and a few fittings, or buy a commercially made one. You can buy bulk desiccant on Amazon that changes color to indicate when it needs changing. Don't throw it away, spread it on a cookie sheet in you wife's oven and heat it slowly. You can tell when it is done by the change in color.
An alternative to the desiccant drier is a refrigerated drier. They tend to be expensive but are the industry standard. The next item you need for clean air is a coalescing filter to remove any oil or other contaminates. It is just a tube with a filter that catches the oil mist that has been condensed from the oil vapor put out by the compressor. It will have a bottom drain and a gage that shows when it is time to change filters. The last item is your pressure regulator. If you have expensive equipment, put a small desiccant drier right at the equipment also. Run you piping so there is a continuous slope to a drain(s.)
Compressed air is expensive to generate, seal up all leaks and don't let air bleed from the drain on the compressor. My shop has all of the above items serving a 25hp screw compressor and a 10hp backup. Kaiser has a good online presentation on air systems.
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post #6 of 18 Old 10-08-2017, 02:17 PM
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Question...

Quote:
Originally Posted by Maylar View Post
I have one of these -

http://www.eastwood.com/devilbiss-ai...SABEgLBwPD_BwE

I mounted it to a cheap hand truck so it can be moved around the shop. I run full compressor pressure to it and use the regulator that's on the filter.



Note that the hose between the tank and filter is an important detail. Air right from the compressor is hot, and hot air can hold a lot of moisture. The hose gives the air time to cool down so the water condenses, making the water separation much more efficient. On really humid days I'll coil the hose in a cooler with ice.
I see quick couplers from the compressor to the filter and on the filter. Why would you need those ... other than the obvious need to
have direct air from the compressor, no filter? Wouldn't you get more volume with a direct line/hose since the couple reduce line size by at least one 1/8"?

I wonder if an transmission cooler with a pressure rating of 150 psi or greater would work for an air cooler? Also if a flared fitting copper line coiled in a water bucket would work pretty well.

I should probably eliminate the couplers from my main feed line at the compressor since I rarely disconnect it. I run one line and switch between full tank pressure for air tools and the air gun OR regulated pressure for spraying. I could just run 2 permanent" lines equally well. I use more air tools than spray guns except on a automotive restore project, but that's just me.

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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post #7 of 18 Old 10-08-2017, 02:20 PM
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Get one of these, you will have to solder on fittings to reduce the line size to what you need this particular drier hold 4 "cores" that would give you 192 cu inches of desiccant, that would last a long time and when it does get full, just cook them as stated earlier. There is a way to make them dry out with out cooking them, but you would need a big ball valve for a rapid depressurization

http://www.ebay.com/itm/Sporlan-C-19...cAAOSw3ydV0OxH
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post #8 of 18 Old 10-08-2017, 03:32 PM
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I thought I was the only one that did that keeps your tank from rusting also.
It might help but I've got a commercial Ingersol Rand compressor in my shop I can't use because of a hole in the tank. It did last for about 20 years before going out. I can replace the tank but have to take off work and go 40 miles to get one.
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post #9 of 18 Old 10-08-2017, 06:00 PM
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Originally Posted by Steve Neul View Post
It might help but I've got a commercial Ingersol Rand compressor in my shop I can't use because of a hole in the tank. It did last for about 20 years before going out. I can replace the tank but have to take off work and go 40 miles to get one.

Check with an LP gas dealer in your area, you can buy "salvage" tanks pretty cheap, they will work fine but some tank makers built the spec tag out of regular steel and after the years it rusts over so they can't read the specs of the tank so they won't fill them (Just a way to hose you more)

99% of them are fine, Trenton sells 250 gallon salvage tanks for $105. What they don't sell the ship to Mexico to have them sand blasted hyrdotested repainted with a new stainless steel spec tag

The air will smell for a while, or you can fill it with water and dump it a couple times and it will go away
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post #10 of 18 Old 10-08-2017, 07:45 PM
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I try to do as much as I can to keep the water from getting in the tank first.

I also run a big enough compressor, and use it enough that I don't want a continuous air leak, that makes no sense to me, you are adding unnecessary wear to the compressor head and motor.

I built a cooler out of copper pipe that has air pulled across it by the compressor head pulley/fan, it's over 8' of pipe in a 1'x1' grid. It feeds into the tank, but that union has a drop leg fitting with a drain valve, a lot of water comes out of that valve.

From there I feed into an output valve with another drop leg to drain water off, then into a separator with an auto drain that feeds the shop airlines. That separator was about $100 or so. Then each outlet in the shop has a cheap HF separator. I have NO moisture in my air, my media blast cabinet is very sensitive to moisture, I don't do any compressed air paint spraying though.
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post #11 of 18 Old 10-08-2017, 08:14 PM
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Quote:
Originally Posted by Catpower View Post
Check with an LP gas dealer in your area, you can buy "salvage" tanks pretty cheap, they will work fine but some tank makers built the spec tag out of regular steel and after the years it rusts over so they can't read the specs of the tank so they won't fill them (Just a way to hose you more)

99% of them are fine, Trenton sells 250 gallon salvage tanks for $105. What they don't sell the ship to Mexico to have them sand blasted hyrdotested repainted with a new stainless steel spec tag

The air will smell for a while, or you can fill it with water and dump it a couple times and it will go away
I don't know, it sounds like a lot of work to me. On a compressor tank it has a plate to mount the motor and pump. It has an outlet for a check valve and a place for a drain and outlets. It's probably painted on the inside where the propane tank maybe isn't. A new compressor tank runs about 400 but I can quickly transfer the parts over.
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post #12 of 18 Old 10-08-2017, 11:04 PM
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If you are in a situation where you need dry air get a refrigerated air dryer, not cheap, but bargains do come up on Ebay, plan to spend several hundred dollars, it will be worth it.

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post #13 of 18 Old 10-09-2017, 11:01 AM
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Quote:
Originally Posted by woodnthings View Post
I see quick couplers from the compressor to the filter and on the filter. Why would you need those ... other than the obvious need to
have direct air from the compressor, no filter? Wouldn't you get more volume with a direct line/hose since the couple reduce line size by at least one 1/8"?
Versatility, since my compressor serves multiple purposes ranging from filling tires in the driveway to running an airbrush in the workshop. I like to have it mobile and configurable. Someday soon I'll build a big one that'll be permanently plumbed in the garage. But yes, I'm sure I lose some flow with the connectors.

Quote:
I wonder if an transmission cooler with a pressure rating of 150 psi or greater would work for an air cooler? Also if a flared fitting copper line coiled in a water bucket would work pretty well.
A coil of copper pipe inside a mini fridge works very well. My DIY coiled hose and Styrofoam cooler with ice is surprisingly effective.

Dave in CT, USA
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post #14 of 18 Old 10-09-2017, 11:11 AM
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Quote:
Originally Posted by Steve Neul View Post
I don't know, it sounds like a lot of work to me. On a compressor tank it has a plate to mount the motor and pump. It has an outlet for a check valve and a place for a drain and outlets. It's probably painted on the inside where the propane tank maybe isn't. A new compressor tank runs about 400 but I can quickly transfer the parts over.

Mount the compressor/motor assembly remote on a concrete slab and pipe it to the tank. An LP tank is 1/4 thick, quite robust

And also it would get more run time per cycle, so it would get the compressor up to operating temperature. If a compressor is over sized it doesn't get a long enough run time to heat it up good enough and that causes moisture to condense in the oil, making it milky causing it to have to be changed more

Last edited by Catpower; 10-09-2017 at 11:15 AM.
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post #16 of 18 Old 10-09-2017, 03:51 PM
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bold type face and underlined?

I guess you wanted us to hear you?

Why does every straight run drain back into the compressor? Each time a tool is used all the residual condensate still "draining" will be forced out the line into the tool. That makes no sense to me.

A drop tube with a release valve at the bottom in the lines sloping away from the compressor makes more sense, but what do I know?
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post #17 of 18 Old 10-10-2017, 08:59 AM
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Please excuse the "bold" typing, did not realize it was till I posted it. Never heard of bold print creating a negative tone before. What I said is simply what I did and with good outcome. Common sense tells me that unless I am using air continuously which I do not. Any condensation will run back to tank. I do have a drain on each vertical line. I would not want the lines to run towards the outlets. I like any water to be in main tank and disperse w/ auto valve. It works for me and just offered it as a suggestion to original post.
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post #18 of 18 Old 10-10-2017, 09:52 AM
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If that works for you, great!

It doesn't make sense to me however, for the reasons I stated. A web search brought up this diagram:

http://www.sharpe1.com/sharpe/sharpe...+Piping+Layout




I

In the interest of full disclosure, it also bought up this image:


This arrangement does NOT allow the moisture back into the tank, but permits draining it before it gets there. Moisture in the tank, whether in the liquid or vapor form is just not a good idea and any thing you can do to reduce it would be advantageous.... just my opinion.

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
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