HVLP FAQ - Frequently Asked Questions

Here are some commonly asked questions about HVLP (High Volume Low Pressure) sprayers and the answers, such as fluid set size, dilute latex and stages. There are some not so common Q & A that may benefit you as well.

Questions

Answers

What cleaner should I use to clean my HVLP sprayer?

Typically you should use whatever the thinner is for the material you are spraying, for example:

Latex = Water
Oil-base = Mineral Spirits
Lacquer = Lacquer thinner

How often should I clean my HVLP sprayer? After every Use! And thoroughly!
How often should the Air Filters be cleaned? The turbine filter must be clean at all times to provide sufficient air flow to cool motor and atomize the fluid. Check the turbine pre-filter daily for cleanliness. Check the main filter weekly at a minimum.
When do the motor brushes need to be replaced? The motor brushes should be replaced either every 600 hours of use or annually. Failure to replace the motor brushes will cause motor failure
What size fluid set should I use? This depends on what you are spraying:
  • #2 Fluid Set - Inks, dyes, non-wiping stains, automotive finishes
  • #3 Fluid Set - Auto finishes, lacquers, stains, enamels, epoxies, urethane, varnish
  • #4 Fluid Set - Lacquers, stains, enamels, epoxies, urethane, varnish, primers
  • #5 Fluid Set - Enamels, epoxies, urethane, varnish primers, industrial finishes, latex, multi-spec
  • #6 Fluid Set - Industrial finishes, latex, multi-spec, butyrate, oil wall paints
  • #7 Fluid Set - Industrial finishes, latex, multi-spec, butyrate, oil wall paints
What is the difference between the different sizes of fluid sets? The larger the needle and fluid nozzle, the greater the flow of paint from the paint cup or tank will be. The larger the air cap, the greater the volume of air there will be to atomize that paint. In general, thinner paints should use a smaller fluid set, while thicker paints will need a larger number.
What is the maximum Turbine Hose length allowed for my HVLP Sprayer. This answer will depend on who the manufacturer of your HVLP unit is.
If you have a Graco HVLP Unit, the maximum lengths are as followed:

HVLP 2500........................................................................... 40 ft (12 m)
HVLP 3800 .......................................................................... 60 ft (18 m)
HVLP 4900........................................................................... 60 ft (18 m)
For more detailed information on hose lengths, sizes, and what is compatible for your HVLP system, contact the manufacturer of the system, or give us  a call at 1-800-542-8300

How does the air from the gun eliminate overspray? A cone of air, produced by the gun, carries and directs the paint from the gun to the surface, minimizing overspray and increasing transfer efficiency.
What is the G40 Gun, and what machines are they used for? The G40 Gun is specifically designed for Graco's FinishPro paint sprayers. The gun Allows you to spray Fine Finish materials at lower pressures in air-assisted airless mode – resulting in an exceptional finish AND allows you to spray a full range of paints, primers, and other heavier materials in airless mode. It also has a bonded air and fluid hose which are permanently welded together, eliminating the
need for fasteners or ties that can get caught on the jobsite
I'm in the market to purchase a Graco 4900. In my internet research it appears Graco does not suggest a method to determine proper viscosity for diluting paint other than cut the paint until it drips one drop per second. Before I make a major investment I would like to know if there is a more accurate way to determine the viscosity for the high end Graco products.

The most accurate way to test viscosity is with a Zahn cup. For most finishing materials you would want a #2 Zahn cup. You can usually get them at an automotive paint store or a store that sells ink and supplies for printing presses.

In a nutshell... while holding your finger over the hole in the bottom, you fill the cup with a specific amount of material. Then while watching a clock with a second hand or using a stopwatch, you slide your finger off the hole and let the material flow out and as soon as the stream has stopped, note the time; don't wait for it to drip every last bit of material, you want to stop counting when the stream breaks.

Here is some info on which Graco fluid sets to use based on #2 Zahn cup results;

Inks, dyes, non-wiping stains, automotive finishes
14-16 seconds

Graco part # 245591 (Special sized set for light viscosity materials)
Graco part # 244123 - Fluid set #2
Graco part # 245592 (Special sized set for light viscosity materials)

*

Automotive finishes, lacquers, stains, enamels, epoxies, urethanes, varnish
16-20 seconds

Graco part # 244124 - Fluid set #3

Lacquers, stains, enamels, epoxies, urethanes, varnish, primers
21-30

Graco part # 244-125 - Fluid set #4

Can the same sprayer be used for poly & varnish as well as lacquer?

Can it be cleaned well enough to avoid cross contamination, particularly in lacquer?

Is an extra spray gun and hose a good option to help in the cross contamination, or are there other options?

Yes, but...
You will have clean your sprayer very very thoroughly after each use and...

You should have one hose just for the lacquer and one for the polyurethane & varnish. At the least, you should also have a filter set (gun and pump/manifold) for each material and these should be 100 Mesh.

Preferably you would have one gun just for lacquer and another for the varnish and polyurethane.

Ideally you would have one sprayer for just lacquer to avoid contamination.

Also, if you were to throw latex into the mix, which we don't recommend if lacquer is in the mix, you may want a hose, gun, tip and filter set for that as well.

Lacquer thinner is a fairly "hot" solvent that will soften, loosen and/or dissolve most other materials that were not cleaned out of the system and will contaminate your lacquer, plug filters and tips. That being said and if you must use one sprayer for all materials, you may want to store your machine differently when it is not in use, a way we don't recommend as it will ruin your pump packings and other seals in your sprayer and that way is;  with lacquer thinner with a few splashes of engine oil in it.

What is the difference between a Turbine HVLP and a Compressor powered HVLP?

Turbine units use fans to produce a large volume of air at lower pressures. The more fans (aka blades), the more power that the HVLP will be able to generate. These blades are called stages, and currently 2, 3, and 4 stage HVLP units are produced. Thinner materials, such as stains, will be able to be sprayed with fewer stages, while thicker materials, such as oil-based paints, will need more power to be sprayed. The greatest benefit to a Turbine HVLP is that it is portable, and much more lightweight compared to a compressor-HVLP.

Compressor Powered HVLP units use an air compressor to provide the amount of air needed. You may use a home air compressor to help provide to air (however you must make sure the air supplied matches the air needed for your HVLP unit), however many HVLP units (such as the Graco FineFinish 9.5 HVLP sprayer ) have a built in on-board air compressor.