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The Best Way to Feed Spray Guns for Painting

01/14/2009 6:00 AM

Dear friends,

What is more effective for feeding painting spray guns - diafragm pump (Triton) or Pressure tank with agitator (Binks)

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#1

Re: Efim

01/14/2009 7:44 AM

A diaphragm pump will give a pulsating pressure, a pressure tank will smooth out any pulsation from a pump, so I think the tank is better.

Del

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#2

Re: The Best Way to Feed Spray Guns for Painting

01/14/2009 11:25 PM

At the factory i work in we paint truck trailers and have found this setup to be very good, we use a husky 515 diaphram pump regulated at 90 psi with Graco outlet filter 214-570 attached and a Graco 214-706 g series regulator attached to the output this delivers enough paint for up to 3 paintlines at 38 psi and there is no surge flow rate is approx 2.5 gpm/12 lpm delivery unregulated. we use the stainless regulator as cleaning is minimal and if it does block up cleaning time is around 5 minutes.

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#3

Re: The Best Way to Feed Spray Guns for Painting

01/14/2009 11:41 PM

Both have problems and both have benefits. The simple solution in this case is NOT the best. We run spray guns with intermittant operation and the real problems come from the system you use between the pot/pump and the guns themselves.

The solids proportion of your paint will settle in low sections of your system pipework when there is low paint flow and give you variation in colour/metalic fleck/pigment/solids content across time.

Our system uses diaphram pump with 500% capacity to the spray gun use/capability with pressure accumulator in paint line to the gun and a return path so that paint not drawn off by the gun is returned to the pot, providing constant cycling of paint through the lines and stirring by the material returning to the pot.

Thus we have the benefit of an actual volumetric pump combined with the benefits of a stable pressure supply and no opportunity for the paint to settle.

Pots of mixed paint are also independantly stirred so that solids do not settle.

Using this system, we maintain colour match for interchange components over 4 years of production where each colour may be processed 16 to 20 hours per week.

The main vats are only 30L capacity and we add 8L when there is around 10L remaining.

Both suppliers have adequate equipment to provide a good outcome, it's just a matter of making sure that you build a system (not just delivery device) that suits your paint, guns, and environment.

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#4

Re: The Best Way to Feed Spray Guns for Painting

01/15/2009 5:53 AM

Thanks for useful information!

What about use of electrostatic spray gun (Graco Pro XS 4 85 kV)?

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#7
In reply to #4

Re: The Best Way to Feed Spray Guns for Painting

01/15/2009 3:16 PM

We have tried these electrostatic guns the paint lines and guns are high maintenance and operators keeping the guns clean were our main problem it, appeared that if you dipped the whole gun into a bucket of solvent to clean them they dont work as well but the system did reduce paint use when used correctly.

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#5

Re: The Best Way to Feed Spray Guns for Painting

01/15/2009 6:22 AM

Straight forward. Diaphragm pumps will work with any paint which won't dissolve the diaphragm. They are generally the only ones for use with latex paints (emulsions to pommies & british commonwealth) as piston, lobe and the like can break the emulsion/latex. Graco pumps are pistons and so best suited to solvent based paints.

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#6

Re: The Best Way to Feed Spray Guns for Painting

01/15/2009 2:40 PM

I'm sorry, your question can not be answered in the form it is presented.

eg. what kind of car should I drive? what tastes better.

One you have a major unknown (Application), two is personal preference and three is volume/scale.

As stated all have good and bad points. Obviously you paint on a scale way beyond my normal usage. About an ounce at a time. I don't consider my self a painter but have done show cars, houses, industrial concrete floors, boats, bondo buckets and scratch built models.

I do like the recirculation system, even on models settling is an issue.

I may have little to add but I will not know until the parameters are a little less open.

Brad

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#8

Re: The Best Way to Feed Spray Guns for Painting

01/15/2009 4:08 PM

We're painting plastic parts with our system and so electrostatic guns have not yet been adopted. Sorry but cannot give you any advice there.

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#9

Re: The Best Way to Feed Spray Guns for Painting

01/15/2009 4:19 PM

We're a bit more "industrial" in our painting than most. Our "guns" look more like pheumatic valves with three lines (air in, paint in and return line for excess paint) around 60mm x 60mm x 40mm, clamped onto a stand. The parts move (on a conveyor) past the guns and the guns only spray when there is a part in front of them. The conveyor is routed such that two guns can be used for undercoat, then a drying oven and then another two guns for overcoat. (Overcoat and undercoat can be different paint)

We can paint 45 parts per minute, we have 6 pots of mixed paint (undercoat and finish coat) in the "kitchen" (flamable good store) and all 6 are running continuous circulation through the paint lines to the spray gun manifold.

Paint/colour changeover takes around 30 seconds per gun, and fixtures on the conveyor can be exchanged by operators "in cycle" so that we can do running changes for painted product.

Paint Lines are only flushed once per year for Christmass shutdown so we can shut down the pumps.

By the way, pumps are pneumatic operated due to flamable nature of the pains and solvent that we are using.

If anyone wants more info, then send me a line.

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