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  • HVLP How to avoid explosions?

    Hi all,

    I know some of you have used/own HVLP systems, I have my woodworking shop in my garage and I have tools everyone one have: TS, jointer, planner, router, radio, floor fan etc.

    I don’t have any appliances, like water softener, refrigerators, water heaters, air-conditioners and so on…
    That all said, I am interested in buying a HVLP but after reading some comments about explosions I am very concern.
    My question is very simple: How can I avoid, any chance of explosions while using a HVLP?. I really don’t want to have an explosion proof fan, and I do want to spray stains and Poly (Oil base)

    Any advice would be appreciated.
    Olilugo

  • #2
    use just plain old fans if you have a entry door rhat leads to the outside.make a 2x4 frame work that can hold 2 or 3 box fans that can be placed in the door opening with a screen on the front,if that is not an option and you have roof vents place one fan so it is pulling freash air in and another so it can be pushing bad air out.the biggest reason for an explosion is the air gets thick with fumes and then a skark happens butif you keep the air moving with fresh air coming in and bad air being forced to leave the chance of an explosion it reduced by about 91% the fact that you dont have any of the other things in you shop reduces it another 8% witch leave just one percent of human error(like lighting up a cigg to starting a power tool)and the fans.
    9/11/01, never forget.

    Comment


    • #3
      Generally speaking, an environment subject to explosion has to be fairly laden with flamable mist or fumes. In such cases, a non-explosive proof fan on the exhaust end of the vent system would definetly be a source of igniton, as fumes would be passing over and through the motor. Of course this only applies if you're loading the air faster than it can be moved. So make sure that the volumn of the air exchange is such that there will be no build-up of fumes and spray mist. Otherwise, you should use the fan on the upstream end of the system where only fresh air will pass through the motor. (When selecting a fan, consider it's cfm in relation to the size of the room.)

      An HVLP system should have much lower mist in the air than a conventional spray gun. The whole idea of the HVLP is to put more product on the object with less overspray. For health's sake, a good resparator is vital.

      Any equipment in the spray area should be turned off and certainly you don't want to have a woodstove, exposed electric heater, pilot light, or even an electronic ignition source in the area.

      I hope this helps,

      CWS

      Comment


      • #4
        CWS is right, a non explosion proof fan on the outlet side is not good. Also, a fan could actually make things worse by pumping air in that would create a mixture that falls between the upper and lower explosive limits of the substance being sprayed. W/O the fan the product concentration may be so high (ABOVE the UEL) that it could not easily ignite. Certainly you would have to be doing some heavy duty spraying to get in that situation, but its possible I would think. I have thought about a HVLP sprayer also, but the quantity of work I put out in a home hobby type woodshop does not warrant it I think once you factor in the safety risks, added costs for PPE, a make-shift spray booth, some type of ventilation, on on and on. It's kinda like having a wood burning stove. The stove is cheap enough its the pickup and chain saw and everything else you need to cut wood that adds up.
        ---------------
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        Comment


        • #5
          So, reading this I wonder. Is the solvent in the paint the flammable item or the solute? Once the pigment and binder have left the mixture, is it the remaining solvent fumes that are flammable? I have never sprayed anywhere buy my garage with the door wide open, so I have yet to develop this issue, however I am planning a 16X20 out back in the next few years (appears the Missus wants the garage for a family room) so I want to make sure that I accommodate ventilation as a part of the design. Now, I shoot water base primarily, any concern other than the obvious paint respirator?
          Only a surfer knows the feeling. Billabong ca. 1985 or so

          Comment


          • #6
            Normally, the solvent which is volatile and evaporates (and mixes with the air) is the first flammability concern and is also the one that can become explosive in nature. However, a point often overlooked is that the dried overspray is also extremely flammable. The resin component of most paints (the part that holds all the color pigment together and provides characteristics like gloss and water -proofing, etc) dries as part of the coating but will burn. Overspray provides a lot of surface area for the material to have contact with oxygen in the air. This will let it ignite readily (cigarette ash, static spark, etc). Even iron (which isn't "flammable) will burn in the form of iron filings as will steel wool if you add something acidic (how many use steel wool with Barkeepers Friend?). The solution is to use cheap plastic drop cloths or newspapers and dispose of them in a closed metal can (galvanized trash can, etc) as soon as you're done spraying. That goes for all your thinner rags, etc, altho those are more safely disposed of by putting them in a can full of water as the heat generated from the thinned paint as it dries can cause spontaneous combustion.
            HTHs
            Practicing at practical wood working

            Comment


            • #7
              Ok! I am very concern now.
              I read some very deep opinions which I find it very hard to follow. Sorry I am probably not the smartest woodworker.

              So that I can understand, I have a shop in my garage, it is a three car garage and it has a big two car door and a one car door.

              If I plan on having all the doors open, no other tools running when spraying, live in Texas, and I am only planning to use the spay in oil stains and Poly.
              I also have to say this is just a hobby, meaning I would only spray one cabinet every two – four months… not very active.
              Question: where would I put the HVLP unit and where would I put a fan.
              I am looking for something like: open the two garage doors, right outside the small door put the turbine. Locate the cabinet so that you face towards the big door, not towards the house. Behind you point to the outside put a fan.
              And so on…. Continue to run the fan for about two hours after spraying so that all the fumes go and everything is safe to close the garage.

              The HVLP I am looking at has a 25’ hose, and I could only image I would only spray for about 10 to 30 min or whatever it takes to do a one pass stain, wait a day or two apply first coat of poly or sealer. Wait for another day or two apply second coat and so on… nothing fancy.

              Thanks to everyone for trying to educate me, however I am a bit dense and I need easier directions since I am not up-to date with the entire woodworking/painting lingo.

              I hate to say it but I don’t really want to build a explosion proof room nor would I want to rebuild my garage so that I have a bunch of stuff I don’t use in a regular basis.
              It might be the real answer is to continue to apply my stain and poly by hand which is fine however everyone talks to much abut the HVLP units and they say it is an excellent investment and I am building a big unit( L shape desk that the top expands 75” long) which it will make it a bit difficult to just do it by hand, not impossible just difficult.

              olilugo

              Comment


              • #8
                Olilugo,

                Frankly, for what you have described, I don't thing you have anything to worry about.

                The question is whether there is any other equipment in your garage, like a heater, hot water tank, etc. that may provide and ignition source while you are spraying.

                I have two places in our new home where I plan on doing woodworking. One is the two-car garage and second is the basement where I have two rooms joined by a double door. However there is a hot water heater and the furnace in the adjacent basement area.

                I have no problem working in the garage with the double-door open. My compressor will be in a room built on the side of the garage and I'd probably put a fan in the window there, simply to provide some minimum air flow on a still day.

                Only concern with working in the garage is spray drift to the neighbors'. I don't want any complaints because their car has spray drift.

                In the basement, I won't do any refinishing at all. I don't want the smell drifting into the living quarters. With the water heater and furnace in the ajacent area, I don't want to worry about that either. So all oil-based thinner, poly, paint, etc. will be in the garage.

                Biggest problem I think you and I will face in the garage, is dust getting into the finish as we work. So we need to deal with that, and I would have to see how much a fan is really going to be needed. For what you described: with the doors and/or windows open, and no ignition source, I'm not sure that a fan would be required.

                When the work is completed, I'd probably leave a window or door open slightly, so that the fumes can vent.

                I hope this is helpful and less confusing,

                CWS

                Comment


                • #9
                  olilugo: For what you are planning and the amount you are intending to spray, what you describe should be fine. (I would protect stuff against overspray with dropclothes, etc). To keep the dust down, you will probably be okay with just the downwind door open, as it will cause a bit of a vacuum effect and help pull out the fumes. Wait to open the other one until the coating surfaces appears to dull or do it manually (don't use the electric door opener and disable the automatic feature so someone doesn't hit the switch while you're working.)
                  This is all supposing you don't live where they just caught that 23 foot alligator (between Athens and Palestine, TX). If you have those hanging around, you may want the doors closed and just stay with hand application
                  Practicing at practical wood working

                  Comment


                  • #10
                    Thanks you all.

                    I feel more at ease to know I don't have to spend so much more just to spray a couple of cabinets.

                    However I will improve on my respirator, I will protect everything before I start spraying.

                    Dust is not so much of a problem for me. I am a clean freak, I think I spend more time cleaning that actually woodworking.

                    I am probably planning to by the fuji Mini 3 stage for abot $500.

                    No aligators in Austin.

                    Again, Thanks to everyone.

                    Regards,
                    olilugo

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