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Posted: Sep 11, 2009 10:50 PM
Whats everyone using to apply coating?

I have a Graco GH833 which is fairly slow. I was looking on You tube and there are several applicators that look like they are applying at 4-5 times the rate that I can with silicone.

Is the GH 733 that much faster?

What else is out there that I should be look at?


Dennis Davidson
Posted: Sep 14, 2009 08:49 AM

GH833 - 4,000 psi, 4gpm
GH733 - 3,500 psi, 3gpm
A GH833 "should" be able to run circles around a 733
Are you using a transfer pump to feed the 833 or are you using a siphon tube?
If using a transfer pump, what size is it and what size is the hose?
What size spray hose are you using?
What gun and tip are you using?
What is the solid volume content of the silicone your using?

Posted: Sep 14, 2009 08:06 PM
Hi Dennis

I am only using the standard siphon that came with the unit when I purchased. What type of drum pump should I be using and will it help?

My hose is 1/2 inch with a 3/8" whip.

I am using between a 619 to a 631 on the spray tip and it is a standard Graco Sprayer that came with the unit with an extension.

We moved from West 465 which is around 68% to Bayblock, which is just over 60%.

If my 833 should be doing 4 gpm, which is a little more than a square a minute, we are at least 5 minutes slower than that.

Should I be using a larger tip?


Dennis Davidson
Posted: Sep 15, 2009 10:14 AM

There's most of your problem, no transfer pump.
I've had a LOT of debate on this subject. Without a transfer pump your main pump is doing double duty. It's having to not only create and maintain the pressure requirements but also to pull (siphon) the material through a small hose/tube. The hose and tube that comes with every pump is designed to siphon paint or low viscosity products. And gravity feed isn't a good idea either. (I'm sure someone will debate that point). I know the idea is to not need an aircompressor, but it doesn't take much for just a transfer pump. I use a 5:1 Monark drum pump with a 3/4"X20' hose. The hose needs to be rated a min. 500psi, 1,500-2,000psi is better. I use a 1,500psi transfer line as a safety in case something gets lodged in the main pump's lower ball. This creates back pressure that can (and will) rupture a weaker hose. 1,500psi is also a good safety rating because the foot valve on the transfer pump will blow off at that pressure (had it happen a few times), which is much better than a hose rupture.
The material your using should not be a problem unless it's cold. I don't think you'll have that problem in your area.
Your hose should be larger, atleast the first 50-100'. The longer the hose the larger it needs to be.
Tip size: I use a 631 for just about everything. It's the perfect size. You don't get extremely high production, but what you do gain is control and consistency. I've sprayed side by side with other applicators who used larger tips and at the end of the day I had more done using less material. Accuracy counts!
Brian Bothun
Posted: Sep 07, 2011 08:33 PM
I have a GMAX 7900 can I run a transfer pump with this sprayer also to up my application rate?
Dennis Davidson
Posted: Sep 09, 2011 05:15 PM
The one thing you need to remember is that the transfer pump's function is to "transfer" or supply the material to the main pump. So, under normal conditions, adding a transfer pump will only increase the production or flow rate of the main pump if there was insufficient flow of the material being supplied to it in the first place.
Posted: May 01, 2012 11:57 AM
How does some of the air powered sprayers compare to the 833 or 733? A guy we've sprayed with a couple times swears by his...i think his is a Bulldog? I haven't seen it in action yet. We're getting ready to upgrade from a smaller unit and want to get the best one possible. Problem with air powered is I think we would have to upgrade our compresser as well, and always keep our spray rig on site. 833 looks like a better option for less money than the 733 but some reps swear by the 733. I'm guessing because of lack of experience with 833.

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