HVLP sprayers

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  • leehljp
    Just me
    • Dec 2002
    • 8429
    • Tunica, MS
    • BT3000/3100

    HVLP sprayers

    What is the basic operating differences between these two types of HVLP sprayers? (Gravity feed vs All in one setup) I know one uses the air compressor (gravity feed) and the other (all in one) uses its own large hose. But in terms of production, ease of use and cleaning up, which is overall more effective?

    Gravity Feed automotive:

    Gravity Feed spraygun with regulator:


    VS

    Spray Gun Kit (all in one)


    I bought the all in one back in 2000 for about $50. and have used it twice. It works well once the right balance in viscosity is reached. It is a little difficult to clean but works well if the set up is prepared beforehand - i.e. accessible to all sides easily with the sprayer and hose.

    What is your opinion of the effectiveness and ease of use and cleanup? I sure would like to know. I hate the cleanup of the all in one but I really like the results of “Sprayer” painting over brush painting or spray can painting.
    Hank Lee

    Experience is what you get when you don't get what you wanted!
  • twistsol
    Veteran Member
    • Dec 2002
    • 2892
    • Cottage Grove, MN, USA.
    • Ridgid R4512, 2x ShopSmith Mark V 520, 1951 Shopsmith 10ER

    #2
    Hank,

    Gravity feed vs suction feed is independent of whether the spray gun is driven with a compressor or a turbine. You can get gravity or suction feed guns either compressor or turbine driven systems.
    • Suction feed works throught bernoulli effect that causes suction when air moving at high speed passes over an opening. Air from the turbine or the compressor is passed over the tube that goes into the finish cup and and sucks up finish and mixes it with air on it's way to the needle and cap the air / finish mixture is atomized.
    • Gravity feed is just that, the cup is on the top and the finish is pulled through gravity into the air stream where it is then atomized. Some have a tube that goes tot he gun cap to add some pressure to the finish cup to assist gravity.
    What makes a sprayer HVLP is how it handles the air. In the old non HVLP compressor driven guns, the pressure used was fairly high and the finish came out the end of the gun at high speed which meant most, in some cases up to 80% of the finish bounced off. HVLP uses lots of air moving slowly so a much greather percentage of the finish lands on target.

    HVLP guns that are driven with a compressor are often called conversion guns because they convert the high pressure air into low pressure in the gun and then it passes on as it would in any HVLP system. There is a problem with this though. When that pressure is lowered it gives off two things, heat and condensation so you're now spraying with cold wet air. These aren't significant issues in most cases. But consider the condensation already in the compressed air, especially in humid areas and you add that to your finish.

    Turbine driven systems are just blowers that feed large amounts filtered air through a larger tube. Since their is no conversion of the air at the gun, it is drier and warmer.

    Personally, I like the gravity feed guns since they are often smaller and let you spray at odd angles by repositioning the cup, e.g. uspide down under a table if necessary. As far as cleaning, I much prefer the gravity feed. I rinse the cup with water or solvent if I'm not using a water based finsish, then spray a cup of the soapy water or solvent through the gun, and then if using solvent spray soapy water through the gun. It takes 10 minutes and I've never had an issue with any of my guns.
    Chr's
    __________
    An ethical man knows the right thing to do.
    A moral man does it.

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    • leehljp
      Just me
      • Dec 2002
      • 8429
      • Tunica, MS
      • BT3000/3100

      #3
      Thanks for the information. I am thinking of getting a gravity feed and giving it a try. But, I think the real problem is the set up and clean-up is more time consuming than my mind has adjusted to so far. And, clean up requires immediate action. Not good when LOML and texts and phone calls interrupt.

      Still, I like the difference of spray over brush 10 times over. I just need to mentally allow for set up and clean up. Thanks for your experience!
      Hank Lee

      Experience is what you get when you don't get what you wanted!

      Comment

      • twistsol
        Veteran Member
        • Dec 2002
        • 2892
        • Cottage Grove, MN, USA.
        • Ridgid R4512, 2x ShopSmith Mark V 520, 1951 Shopsmith 10ER

        #4
        Hank, cleanup dosn't reaqure immediate action. A good spray gun is airtight. I often spray a coat, leave the the finish in the gun and come back in a few hours to to spray the next coat. I once left my Fuji gun over a week becasue I forgot and had no issues although I wouldn't recommend that as a standard practice. I do always close the air hose valvle when I set down my gun.
        Chr's
        __________
        An ethical man knows the right thing to do.
        A moral man does it.

        Comment

        • cwsmith
          Veteran Member
          • Dec 2005
          • 2737
          • NY Southern Tier, USA.
          • BT3100-1

          #5
          For several years all I had was a "spotting" or touch-up gun. This is a small siphon-feed gun with a 6-3/4 ounce container, and the actuator is an over-head trigger mechanism similar to using an air brush which I was most familiar with at the time. Usually these siphon-feed guns can use slightly more viscous (thicker) paint. I often just watered down latex to use with it and never had a problem.

          The gun itself was a Ludell and I bought it at my local Tractor Supply store for about $18. I used this little thing for a number of years, and used it to spray poly, lacquer, and, as I mentioned, latex paint. Refinished a couple of old Lane walnut tables with it, spray some trim, doors, etc. Still have it and it still works. HF sells a duplicate of this for around $35, IIRC, (HF item 66871).

          Basic reason for my use was that all I had at the time was an Energair twin-tank wheel-barrel type unit that my employer (I-R) made available to employee purchase at the time. It was marketed out of our Davidson, NC plant back about 1976. So it was not a big volume unit, only providing about 7 cfm at 40 psi. All the gun required was about 5.0 cfm @ 50 psi and I generally ran the gun at 40 psi.

          I have a larger siphon feed Campbell-Hausfeld that I used to spray the finish on my deck, as well as a couple of other projects. But at 45 psi, even my 33 gal, 150 psi oil-less Craftsman can barely keep up. I did buy an HVLP "auto-finish" set from HF a couple of years ago when it was on sale, but honestly I have yet to use that.

          I much prefer to spray finish if I can. It's much faster and uses a lot less finish than a brush. Much depends on your need though. You certainly aren't going to use a spray finish inside and even out side you better be very aware of the wind conditions and the neighbors. ( I once parked my brand new at the time, 65' VW in a parking lot, not realizing that an adjacent parking lot was having its light pole sprayed. I ended up hand buffing with polishing compound to get the thousands of silver specks off that sea-blue finish, taking several hours to do so.

          So, I've brushed, ragged, and sprayed finishes like poly and for me the spray was the easiest. Three to four coats by brush and/or rag was the most intense and perhaps the most enduring as it was in layers with sanding in between.

          CWS
          Think it Through Before You Do!

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