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  • Mist coolant system air

    I know next to nothing about mist coolant systems and in fact I have never actually seen one of the critters in captivity, only in catalogs. No where, web sites or printed, that I can find gives the air requirements for one of these things, anyone know the CFM required for a small unit? Do these things work ok?

  • #2
    The balance between settings of the coolant nozzle and the air line pressure can vary quite a bit. That makes generalizing air requirement pretty hard, I would think. That said, I have a Koolmist PortaMist, 1-nozzle unit that was run off of a 7-gal. Craftsman compressor (THIS) one, and it was a fairly equal match. In other words, the compressor had "just enough" CFM to run constantly at 60 PSI line pressure but continually keep up with the requirements of the PortaMist. So using that as one data point, you might estimate 2.4 SCFM @ 100 PSI per nozzle. That is the rating of that particular compressor. Which, by the way, I would not recommend. Running constantly is neither good for your hearing or sanity! Some say not good for the compressor either Hope that gives you some point of reference?
    Last edited by Arthur.Marks; 03-13-2013, 09:15 PM.

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    • #3
      I built my own mister and it runs on 10-15 psi, i ran it off of a small dewalt air compressor with a 15gal tank and it would not only keep up but actually catch up and shut off. I have not used any other mister besides mine but what i was told on this forum is that in general misters don't us much cfm to operate.

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      • #4
        Originally posted by quadrod View Post
        I built my own mister and it runs on 10-15 psi, i ran it off of a small dewalt air compressor with a 15gal tank and it would not only keep up but actually catch up and shut off. I have not used any other mister besides mine but what i was told on this forum is that in general misters don't us much cfm to operate.
        Can you post some pics of the mister?

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        • #5
          Originally posted by digr View Post
          Can you post some pics of the mister?
          I was just about to ask the same thing.

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          • #6
            there are some good threads here if you do a search. its worse than not having one if it just fogs the shops....iirc key's to not having it fog are pressurized coolant and nozzle size
            .

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            • #7
              I got the brass tubes from an RC hobby shop, found a small tube that fit inside the large tube, pressurized air flow out the inner tube and coolant flows out the outer tube. Air pressure is supplied to the filter housing and regulated down to 10-15psi, coolant is picked up in a hose that runs to the bottom of the filter housing and flows into the mister block and is regulated by an adjustable needle valve. I made all the hose nipples and the needle valve, used an oring from a faucet repair kit from the hardware store.
              http://s157.beta.photobucket.com/use...tml?sort=3&o=0

              http://s157.beta.photobucket.com/use...tml?sort=3&o=1

              http://s157.beta.photobucket.com/use...tml?sort=3&o=0

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              • #8
                Originally posted by Mcgyver View Post
                there are some good threads here if you do a search.

                I tried that first, I love this site but since the change the search feature is nothing but an exercise in frustration, basically worthless.



                :EDIT: Well I tried the search function again (searched "mister" same as yesterday and it brought up results this time. Yesterday all it would do is bring up the usual "Sorry - no matches. Please try some different terms".
                Last edited by radkins; 03-14-2013, 09:51 AM.

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                • #9
                  quadrod, Thanks for the pics and the info, now I have a new project for the weekend!
                  Last edited by radkins; 03-14-2013, 09:50 AM.

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                  • #10
                    I use this one from Ebay .
                    works on my grinder. plan to make a couple more.
                    Rob

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                    • #11
                      My Mister

                      A 10" water filter housing makes a good starting point. A piece of 3/4" pvc pipe is a tight slip fit on the center spigot and makes an easy coolant pick up. I use a ball valve (for quick on and off) and a needle valve (for fine adjustment) on both the air line and coolant line. An air regulator is used on the incoming air line to drop pressure to aproximately 10 psi. This assures that the air and coolant are delivered at the same pressure. Turning the coolant ball valve off first helps when you need to fiddle with something else and don't want the extry oil when you are not actually cutting.



                      The nozzle end is more difficult to construct so that it works properly.


                      the basic concept is that the oil is injected downstream of the air inlet which carries the oil down a larger tube and recombines it in droplets near the injector tip. I back drilled a mig nozzle and soldered it to a small copper tube to do this. The dimensions that Bjur uses are contained in their patten. I would really like to know how their mixing valve works. The Magic Arm camera mount works well for positioning the nozzle where you want it.
                      This system is 10 X better than the venturi type misters but it still results in smoke when you are taking heavy cuts. I mostly run WD 40 for the nice finish on Aluminum. I have used the water solubles for steel but mostly revert back to the brush or the squirt can. I have two roll up doors to venelate the shop. The fog from the venturi type misters was literally making me ill.
                      Byron Boucher
                      Burnet, TX

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                      • #12
                        I think after reading up on these things I am having second thoughts about using one mainly due to the problem of fogging up the shop. I will be working in a relatively small area and significant ventilation would only be practical during warm weather so maybe this is not the system I need. The problem is I bought a Seig mini mill that has a DRO that uses the digital caliper type scales that are not coolant proof and there seems to be no practical method of mounting them that would keep them dry. I have to wonder about the accuracy of these things anyway so I might just scrap them and go to a flood type system.

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                        • #13
                          I have a Bijur Fluid-Flex unit. It runs on about 30-35 psi. Although expensive, I don't particularly recommend the Bijur.

                          Bijur's directions say there should be no visible mist. The cooling comes from the refrigeration effect of the coolant evaporating into the airstream, and the cold air is what does the cooling. If you stick your finger in the airstream and slowly open the coolant valve you can feel the sudden drop in air temperature when the coolant starts flowing and evaporating. The coolant valve should be open to the point that a few small drops of coolant should condense out on your thumbnail if you hold it in the airstream. So says Bijur.
                          ----------
                          Try to make a living, not a killing. -- Utah Phillips
                          Don't believe everything you know. -- Bumper sticker
                          Everybody is ignorant, only on different subjects. -- Will Rogers
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                          • #14
                            I have coolant system only on my band saws. Soluable oil is a great purpose coolant.
                            if you can't take criticism, do the right thing.

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                            • #15
                              As far as fogging up the shop goes, If you are getting fog then you are flowing way to much coolant. When i am using mine i turn the coolant flow down to the point that i just see a few droplets form on the work or on my finger. As SGW says, the cool air does most of the work, it's not about using tons of coolant.

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