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Water issues with compressor and sandblasting

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Mr. Fink

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Discussion starter · #1 ·
Hi,
Looking for advice on eliminating water from my compressor system. I am getting a lot of moisture coming in to my cabinet blaster causing the gun to become clogged. I dump the tank before each session. I have tried the cheaper online desiccant filters but they clog pretty quickly. I bought a filter/regulator combo which seems to have helped but I will still have to stop and unclog the gun every 5-10 minutes of blasting. The filter and regulator is mounted at my tank outlet. Is this the best placement? I am connecting a rubber line from the filter to the cabinet. Also, what type of PPE mask/filter should I use? Any thoughts or help is appreciated.
 
#2 ·
You need a heat exchanger to cool it well before it gets to the filters. That will cause the water to condense and you can keep it from reaching the filter. You can make one from copper pipe or get a commercial one, HF has them relatively cheap.

If you're using regular sand, you need a fresh air system. Silicosis is no joke, can kill you. Other stuff can use a P100.
 
#3 ·
#5 ·
Eldon: I like your 'cooler'! Thermally insulating your air line system from your 'hot' compressor will help also. I did that and also used long sections of 'iron' pipe in the middle of my air line system to 'cool' the air a bit before the drops/drains.. and remember on long runs to slope the airlines back towards the compressor (and away from the air outlets) and make sure you have a drain there as well.

Adding another water filter at the outlet to your blaster will help also, but here in the south moisture will also collect in the media (sand or ?) that you're using. Due to our high humidity, the air here doesn't get 'dry' until late winter... and that's not a bad time to sand blast... :)
 
#6 ·
Eldon - nice setup.

Always helps to blow off your supply line before connecting implement.
Water may collect there during idle times.

2 major things from schematic below:

1 - pitch down away from compressor on ALL horizontal runs.
2 - Take offs from all horizontal runs should always be on the top
side of horizontal runs as shown.
Image


Quote below from EXAIR might also be beneficial to others:

At EXAIR, we understand the ins and outs of proper compressed air plumbing. Over time, I’ve made a list of the most common plumbing mistakes and how to avoid them.
  1. Quick disconnects: While tempting and lighting fast, these fittings can limit the amount of compressed air delivered through the orifice of the fitting. If you have performance concerns, check for pressure drops across a quick disconnect fitting.
  2. Inadequate line size: Think of the compressed air line as a water hose. If the hose gets too long or is restricted or too small, there won’t be enough force and flow to do any work. Many compressed air installations use schedule 40 pipe, and the ID and OD dimensions of this pipe are not always what you would think. Engineering Toolbox is a favorite site of mine and they have a handy chart about Schedule 40 pipe here. Always make sure the compressed air line can flow enough air volume for the application.
  3. Pressure drops: Both of the above mentioned problems are essentially pressure drop related issues, but often there are oversights such as the distance of the compressed air line. As the length of the line increases, the pressure drop will increase. Imagine trying to blow air through a 1 ft section of garden hose. Not too hard, right. Now imagine trying to blow through 50 ft of garden hose. No matter how hard you try, all the energy will be lost along the length of the hose. Double check your line lengths and corresponding pressure drops.
  4. No gauges: If you’re operating a compressed air device and you depend on that unit for proper production, it is imperative to know the operating pressure at the unit. This is why EXAIR includes pressure gauges with any kit containing a pressure regulator. There may be 110 PSIG available at the main line, but a gauge at the device will register pressure to the device, which will generally be slightly lower. (This is also helpful to locate any of the aforementioned pressure drops)
  5. Excessive piping bends: Each bend in a compressed air line (especially 90° bends) removes energy from the compressed air. Make sure the line to the point of use is as direct and free as possible.
  6. PSI vs. SCFM: When sizing a compressed air device or system, it’s important to size based on the SCFM and PSI ratings of the compressor. A compressor that produces 100 PSI cannot necessarily operate any device that requires 100 PSI. Be sure your compressor has adequate PSI and SCFM ratings for the needs of the application.
 
#7 ·
I'm surprised no one here has made one using an old refrigerator. I plan on making one that has horizontal runs starting at the top and going down back and forth so the water DOES flow with the air. Then at the end goes from the 1/2" pipe up to maybe a 2" pipe then a 2" T so the air can slow down and allow more of that condensed water to fall out of the air stream. The T goes down for the water and up for the air. To me it sounds like it will work. If the pipe is sloped upwards with the air flow, the water is bound to get blown upwards when using a lot of cfm. So slope it with the flow and catch it at the end. Just noticed that the post above says for it's number one note "1 - pitch down away from compressor on ALL horizontal runs." Makes sense to me! Otherwise the only time the water will run downhill is when you aren't using much air. Full cfm and the water gets blown uphill.

And a question about steel pipe, If I want to change something in the middle of a run, is there a way to add a union without having a pipe threader? Or do you just cut it where it's easy, remove each side, and get pipe cut and threaded the proper length to fit a union?

I'll mention that my early 70's compressor had water in the oil recently. The compressor has it's own bleeder valve that depressurizes the compressor to tank line. Anyway it is built into the compressor and works on centrifugal force. Well that system didn't just let the air out into the atmosphere, it leaked into the compressor, along with condensation. I was overdue for a new pressure switch and motor contactor/start switch and got a pressure switch with the bleeder valve built in (like most these day have). So no more compressed air leaking into the crankcase. A bonus is that it doesn't sound like air brakes on a tractor trailer everytime it stops! A much longer and quieter "hiss".
 
#8 ·
I accidentally made a great dryer by running about 80 feet of PVC pipe underground from my compressor to my paint booth. I put a sump at the low end. I never get any water in the water filter at the booth. Now, when I sand blast, I run a hose back to my shop to sandblast and I can blast for hours with no clogging.
 
#9 ·
If you're doing alot of blasting the HF refrigerator drier in post #3 will give you ZERO water and dry air. Its spendy but flat works. I use mine daily for last 6 years. You can spend money on something that will work or spend it on an unknown then have to spend more in the end.

You need you cabinet hooked to a shop vac with a good filter. Mine I then have exhausted outside. With that you don't need an PPE. But DON'T USE SAND. Use crushed glass or coal slag. TSC sells coal slag as black diamond. The free silica in sand will get in the air from blasting and you won't get it out of your lungs. Even wearing the best mask filter you can buy. Unless you have a forced air hood to wear you'll get it. I own a blasting company and blast for a living.
 
#10 · (Edited)
55 Tony said:
I'm surprised no one here has made one using an old refrigerator. I plan on making one that has horizontal runs starting at the top and going down back and forth so the water DOES flow with the air. Then at the end goes from the 1/2" pipe up to maybe a 2" pipe then a 2" T so the air can slow down and allow more of that condensed water to fall out of the air stream. The T goes down for the water and up for the air. To me it sounds like it will work. If the pipe is sloped upwards with the air flow, the water is bound to get blown upwards when using a lot of cfm. So slope it with the flow and catch it at the end. Just noticed that the post above says for it's number one note "1 - pitch down away from compressor on ALL horizontal runs." Makes sense to me! Otherwise the only time the water will run downhill is when you aren't using much air. Full cfm and the water gets blown uphill.
Click to expand...
Just coil 1/2'' copper inside it. Set it to 35-38*. With inlet and outlet at top. This is how must all Ref driers are setup. Water drains out of a Tee right out the end of the outlet copper coils. Air up water goes down. Have enough drop to collect the water or have an auto blow off. I would also have a bypass at top so if it freezes up you can still work around it. But last I check copper coil was $150 for 1/2'' so not cheap. That's a 1/3 of way to the HF air drier and you haven't even bought or done anything else vs unboxing and pluging in the HF one.



55 Tony said:
And a question about steel pipe, If I want to change something in the middle of a run, is there a way to add a union without having a pipe threader? Or do you just cut it where it's easy, remove each side, and get pipe cut and threaded the proper length to fit a union?
Click to expand...
Most good hardware stores will thread black pipe. If not HF sells a thread set pretty cheap. This is one reason I don't use black pipe vs off shelf air lines I can cut and install anything in 5 mins with Rapid air kit. And don't even get dirty.
 
Discussion starter · #11 ·
Thanks for all the suggestions. I will read back through tonight and try and design me a better system. I could tell the piping near the compressor was hot to the touch, but my gun was slightly cool so I would say it is a condensation issue. I will also check out the TSC black media. Right now I am using just play sand so I will stop using that.
Thanks again,
Ansley
 
#12 ·
The simplest but probably the most expensive solution to water problems with blasting is to get a bigger compressor, preferably a 2 stage. Bigger is better, and incremental steps will help. If you use a cabinet, changing the media often will help, as the stuff you blast off your parts will hold more moisture than clean media, reducing clogging.
 
#13 ·
Mr. Fink said:
Thanks for all the suggestions. I will read back through tonight and try and design me a better system. I could tell the piping near the compressor was hot to the touch, but my gun was slightly cool so I would say it is a condensation issue.
Click to expand...
Any compressor large or small makes water if the ambient air has even the smallest amount of water in it. As the air is compressed it gets hot, and hot air holds alot more water then cool dry air. So even if compressor is big or small IF the compressor is running its making water. The water is in the air, it just condenses in the tank as most times the tanks are cooler. All the water that collects in the tank does is displace air so your 60 gal tank now becomes 55gal for example. Plus it rust the inside of the tank this is why you must drain them daily.

You want your compressor sized to your blast nozzle to reduce the amount of time its running which reduces wear and tear on the compressor and electric motor etc. Most small 60-80gal 15-25 cfm compressors will struggle with even #2 or #3 nozzle which most cabinets are #2's (1/8'') usually but still use alot of air. But they will work, but will need a drier of some kind if blasting over 10-15min at a time.
 
#14 ·
BO185 said:
Just coil 1/2'' copper inside it. Set it to 35-38*. With inlet and outlet at top. This is how must all Ref driers are setup. Water drains out of a Tee right out the end of the outlet copper coils. Air up water goes down. Have enough drop to collect the water or have an auto blow off. I would also have a bypass at top so if it freezes up you can still work around it. But last I check copper coil was $150 for 1/2'' so not cheap. That's a 1/3 of way to the HF air drier and you haven't even bought or done anything else vs unboxing and pluging in the HF one.



Most good hardware stores will thread black pipe. If not HF sells a thread set pretty cheap. This is one reason I don't use black pipe vs off shelf air lines I can cut and install anything in 5 mins with Rapid air kit. And don't even get dirty.
Click to expand...
I have some Rapid Air lines ran as an extension, but they leak a bit. Any cures for that?
 
#15 ·
ETriggs said:
I have some Rapid Air lines ran as an extension, but they leak a bit. Any cures for that?
Click to expand...
Is it the ridge line or the soft 3/8'' line? Make sure the cuts were straight then i use a little lube like diluted soapy water when installing them so the orings don't get pinched.
 
#16 ·
#17 ·
BamaNomad said:
Eldon: I like your 'cooler'! Thermally insulating your air line system from your 'hot' compressor will help also. I did that and also used long sections of 'iron' pipe in the middle of my air line system to 'cool' the air a bit before the drops/drains.. and remember on long runs to slope the airlines back towards the compressor (and away from the air outlets) and make sure you have a drain there as well.

Adding another water filter at the outlet to your blaster will help also, but here in the south moisture will also collect in the media (sand or ?) that you're using. Due to our high humidity, the air here doesn't get 'dry' until late winter... and that's not a bad time to sand blast... :)
Click to expand...
I will be adding a series of 3 fans over it to help cool the piping. I'm still getting a bit of water through. But here in Auburn, its so humid you can pull a fish out of the lake and it won't die.
 
#18 ·
Mr. Fink said:
Thanks for all the suggestions. I will read back through tonight and try and design me a better system. I could tell the piping near the compressor was hot to the touch, but my gun was slightly cool so I would say it is a condensation issue.
Click to expand...
Compressing the air creates heat. When the air expands in the gun, it gets cool, which (which with water in the air) causes condensation. My die grinder for instance gets so cold that it's uncomfortable.
 
#19 · (Edited)
I spent $1000 for a Zeks refrigerated air dryer 14 years ago that was the same price as my 80gal 5hp 2-stage, and it has been worth it. No water ever, even running wide open!
Draining the tank every time you fire it up is important. I know one car dealers shop that their 80 gallon compressor quit because it had 80 gallons of water in it. Any water pooled up in the bottom of the tank will vaporize as the air gets warmer. Humid weather makes it much worse.
And always shut off your compressor when not using. Just last week, a filter drain didn't close, and my compressor ran all night raising the temp in my shop 10 degrees, because I forgot. Lucky it wasn't worse.
 
#20 ·
55 Rescue Dog said:
And always shut off your compressor when not using. Just last week, a filter drain didn't close, and my compressor ran all night raising the temp in my shop 10 degrees, because I forgot. Lucky it wasn't worse.
Click to expand...
I put a large relay/contactor from an air conditioner unit, in the line to my air compressor, that is controlled by the shop lights. When I turn the lights out, it opens the circuit to the compressor.
 
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