Drying compressed air for a sand blaster
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  1. #1
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    Default Drying compressed air for a sand blaster

    Any tips out there for dehumidifying air for a crushed glass blasting operation? Most of the moisture condenses in my compressor tank when it's cold so I'm fine for the first 20 minutes or so, but as the pump head and air tank start heating up warmer air makes it's way down my air hose and into my blasting gun. The result is a wet, sandy sneeze all over my parts and a clogged nozzle.

    Should I look into constructing some sort of intercooler to help drop the air temperature? Or would a moisture trap placed right after a pressure regulator (drop in pressure = drop in temperature = condensed water) be more effective? Is a renewable desiccant something I should even consider for this application?

    Thanks.

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    The really effective water removers use refrigeration to cool the air ,but thats costly,and a centrifugal/swirl water separator as near to your bead blaster as possible should stop slugs of water disrupting your process. ..Paintspray needs more than this ,so if you paint as well ,your system will need to be geared to the requirements of painting.

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    I've only ever had luck with refrigerated air dryers. The various other cheaper products don't work well or long. Desiccant filters are a PITA with constantly changing/drying media. In a blasting application it will be saturated in a few hours.

    Regenerative desiccant dryers are great but are better suited for getting extremely dry air after a refrigerated dryer, and are also more expensive than a refrigerated dryer.


    I recommend getting a refrigerated dryer sized to your compressor and plumbed in between your tank and everything else. Anything you run off of air will benefit being dry.

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    A good inter cooler will help.
    Got one on mine and it is good enough for blasting.
    It will help any thing else you do work better

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    Copper coil in a bucket of ice water? Cheap and easy. 20ft of 3/8 refrigeration coil, two 3/8 compression by 1/4" FIP couplings, some air fittings and a moisture trap. Just add snow!



    The question then becomes whether I would need a heating stage afterwards - since the pressure drop at the gun will drop the temperature even more, leading to additional condensation. Another coil situated in front of a space heater?

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    Getting the hot air coming out of the pump back down close to normal room temp
    Does wonders, quite a bit of the water comes out and stays in the tank.

    Looks much like an ac radiator between the pump and tank.

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    I have never done it myself but I have seen inexpensive setups with a copper coil in a discarded refrigerator. I wish I could remember how the condensate was handled but I can't. The one I saw most recently was in the shop of a luthier who was spraying lacquer and needed very dry air. It probably had 100 feet or so of 3/8" copper coiled inside the refrigerator. It had a solenoid valve mounted at the bottom but I can't remember or ever knew if the valve was on a timer or was manually activated from time to time to purge the water. It worked however and completely stopped the lacquer from blushing.

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    Quote Originally Posted by 72bwhite View Post
    Getting the hot air coming out of the pump back down close to normal room temp
    Does wonders, quite a bit of the water comes out and stays in the tank.

    Looks much like an ac radiator between the pump and tank.
    RIGHT! And it costs nothing in terms of energy usage. Also, run the tank pressure up, and regulate down to the delivery pressure.

    These measures help but, as mentioned, the expansion of air happening at the nozzle cools the air and will allow water to condense - refrigerated dryer is the only sure-fire fix.

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    I have checked the drain fitting on a number of compressors and have found the pipe fitting often goes too deep into the tank. Careful shortening, or adding a parting wheel notch to the amount going into the tank can be a big help to not having a pool of water in a tank.

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    This won't solve your blasting problem, but you really need an automatic drain on your tank to get the most life out of your compressor.

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    Run the air intake for your compressor outside. Your outside air probably has a lower dew point than anything you can get from a refrigerated dryer. Won't work in June or July, but it will work now.

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    What is your budget?

    In another thread I mentioned decent performance by a HF refrigerated dryer



    Compressed Air Dryer - Save on this Compressed Air Dryer


    400 bucks

    I cannot vouch that a new one is going to last as long as one bought 18 years ago


    Do remember if you go DIY that you need to get the water out of the system once you get it to condense.

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    Dyers shmyers. You don't need anything but a properly installed pipe system and a few cheapo water traps.

    I have many years and hundreds and hundreds of hours of mostly cabinet blasting under my belt and practically have never had water issues. The only things I've always had are a properly installed pipe system and a few cheapo filter/water traps.

    My old garage system was galvanized pipe. My new shop system is copper. Here are some examples of takeoff points including ones high in the rafters with pull string valves (from McMaster) to operate the drains remotely. The systems always carry a slope too. (1/8" /ft example)

    So... two or three basic (meaning low cost) water traps and properly installed lines and your troubles are over.

    By the time the air enters my siphon cabinet it has seen 2 filer/water traps. My other pressure pot cabinets will have seen 3. Compressor outlet/sandblaster area takeoff point/pressure pot input. These are basic filter units that practically last forever.

    Look up TP sandblasting. They have installation outlines that show proper water trapping piping systems like I'm talking about. I've seen these types of system outlines elsewhere too. A hose running across the floor doesn't cut it.

    And yes I know... I'm a hack solderer.
    Attached Thumbnails Attached Thumbnails air_1.jpg   air_2.jpg   air_3.jpg  

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