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Air regulator/separator/drier options?

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  • #16

    Re: Air regulator/separator/drier options?

    the ones I sometimes have to fix have sort of a baghouse that separates the fines and it has a sort of a pot that collects the sand and some air settings that sort of change how it recollects. It's a bit like how a carberator may be tuned to work but here are finer adjustments that affect it's performance. instead of mixing gas and air it mixes sand and air. there are different types of sand too and some are more expensive. Likely it has some factory procedure to tune it up. Ive had this one run into a situation where the hopper below the blast cabinet got too full of sand and if I recall there were some settings that affected that. sometimes I'd have to get the sand out of the big hose down into he bottom of the blast cabinet as it sort of choked itself and then I'd get air and not a lot of sand until I took some out from the pipes below the blast cabinet. there was sort of a 6" hose down there and I found I was needing to empty it, likely because the mix ratio was not correct. I never tried measuring the moisture but I bet that's possible too. If I recall right garnet sand was about a buck a pound so it could likely be dried if it's getting too moist?

    some of the outdoor units dont recollect the sand so I assume they use cheaper sand too. I went to an outdoor place a couple of times where they just charge you by the bag of sand and let you go to it, but you wouldn't want to live or even park near the thing, it's a very gritty place. It would be nice to have one to clean up wheels and things that I want to restore. when they work right they save so much time and do a great job.

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    • #17

      Re: Air regulator/separator/drier options?

      The problem with sandblasters is the volume of air required. I have 18ish CFM available (delivered) with a 60Gal tank. I also run my air through 2 coellesing filters, 1 near the compressor (10') and 1 after about 30' of black iron pipe.
      Running more than 10 mins, I will easily start spraying water out my sandblaster, even though the nozzle tip on it is supposed to be 12CFM when using the siphon blast cabinet.

      My compressor can keep up, but the air begins to heat and my filtration cannot strip enough water out of the hot air fast enough to keep up, even though my filtration is rated to match my compressor on paper, reality is different.

      I have a dessicant filter, but it really only gets used for painting because even it would get overwhelmed with 30 mins of sandblasting and Id then have to reprocess the dessicant pellets which is a PITA.

      Blasters might not need "clean" air, but it has to be dry. Ive modified my cabinet to work with an external pressure pot, which helps cut down on air consumption over the siphon cabinet. I can get considerably more run time out of the pot, but its a PITA to have to stop and refill whereas the cabinet keeps recycling the media.

      There are kits out there to update the standard siphon system used on the Princess Auto / Harbour Freight cabs that is supposed to work but I havent tried it yet. Ive spent too much on this thing already! https://www.amazon.com/Skat-Blast-Ca...28a25aefc50bde

      https://www.youtube.com/watch?v=GOBbpZcwF7M

      Honestly I think Im probably going to just go with wet blasting from here on out. If you have a 4gpm pressure washer you can too.

      I also might be considering a refrigerated dryer to solve this problem once and for all.
      Last edited by scooby074; 11-22-2021, 08:50 PM.

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      • #18

        Re: Air regulator/separator/drier options?

        Originally posted by scooby074 View Post

        I also might be considering a refrigerated dryer to solve this problem once and for all.
        I used to work at a large rental equipment company. We rented compressors from dual tank wheelbarrow sized to 500+ CFM Atlas Copco monsters along with pressure pot sandblasters of small to ridiculous sizes. One thing we always stressed with renting out the pressure pots and air compressors is that if someone was going to be blasting for more than 20 mins at a time (ie: near continuous duty blasting) you needed to rent a dryer as well. The pressure pots would accumulate enough moisture in a fairly short period of continuous use that they'd start to 'gum up', ie: nozzles would start to plug with clumps of sand. The large driers we had for rent were mounted on trailers and had refrigerant coolers.

        If I can get my post compressor air temps down from the ~160F+ (measure with an IR temp gun on the outlet pipe) I'm seeing now to under 90F I'll be happy. The DIY articles and videos that have measured before and after the transcoolers are seeing up to 100F reduction in temps.

        Wet blasting isnt an option for me. My shop is too small for an indoor wet blast area, and I have 4-5 months of below freeing temps. Hence why I got the blast cab at an auction.

        I'm not quite ready yet to rig this all up But I'll try and remember to update this thread with my findings.

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        • #19

          Re: Air regulator/separator/drier options?

          Originally posted by cstephens2 View Post

          I used to work at a large rental equipment company. We rented compressors from dual tank wheelbarrow sized to 500+ CFM Atlas Copco monsters along with pressure pot sandblasters of small to ridiculous sizes. One thing we always stressed with renting out the pressure pots and air compressors is that if someone was going to be blasting for more than 20 mins at a time (ie: near continuous duty blasting) you needed to rent a dryer as well. The pressure pots would accumulate enough moisture in a fairly short period of continuous use that they'd start to 'gum up', ie: nozzles would start to plug with clumps of sand. The large driers we had for rent were mounted on trailers and had refrigerant coolers.

          If I can get my post compressor air temps down from the ~160F+ (measure with an IR temp gun on the outlet pipe) I'm seeing now to under 90F I'll be happy. The DIY articles and videos that have measured before and after the transcoolers are seeing up to 100F reduction in temps.

          Wet blasting isnt an option for me. My shop is too small for an indoor wet blast area, and I have 4-5 months of below freeing temps. Hence why I got the blast cab at an auction.

          I'm not quite ready yet to rig this all up But I'll try and remember to update this thread with my findings.
          Having run blasters for work, Ill say this : There is nothing more satisfying than a sandblaster that is working right, and there is NOTHING more frustrating than one that isnt!

          At work, we had dry ice blasters (nice, no real mess to clean) which were great. Our air was pretty good, we had a huge air compressing and processing plant in the plant. I suspect that by its nature, dry ice blasting isnt nearly as unacceptable to water contamination as sand.

          We also had Guysons. They were centrifugal shot blasters. No real air consumption. Items were placed on a table then spinning centrifugal "shooters" threw the steel shot at the items. Like a million little slingshots shooting shot. So nice to use.Set the timer, push the button. Done.

          I think people buy blasters without a thorough understanding of how much air they need and the quality (dryness) of air required AT that volume. I met specs on paper but reality is different. I probably would need my system sized for 30cfm+ to be able to deliver 12cfm continuous to the gun without oversaturating the air and dryers.

          As far as dryers go, Harbour Freight offers a refrigerated dryer thats supposed to do 21 CFM for $450USD, but who knows what it really will do! Reviews seem OK. If I had easy cross boarder access Id consider it but I think Id likely go with a more reputable brand like an IR.

          Of course before you install the refrig dryer, you should run the air through conventional air filtration to knock out water and dirt first.

          Im also going to make an Aftercooler from an automotive Transmission Cooler like you suggest, that will help drop the air temp a few degrees as well. Ill likely do this before i do the refrigerated cooler, cant hurt.

          Keep us in the loop with whatever you come up with. Its a good topic.
          Last edited by scooby074; 11-29-2021, 10:35 PM.

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