TheSamba.com :: View topic - What does "At the cap" setting mean on HVLP guns?

Thu Nov 23, 2006 11:50 am

Hey all, quick questions: the spec sheet on the DCU2021 I am using says the air pressure should be set at 8-10 PSI at the cap on HVLP guns. I have an air regulator on my gun, mounted at the base where air enters the gun. When I squeeze the tigger the air pressure goes down. Is that the setting I am looking for? 8-10 PSI with the trigger depressed? It make sense to me but I would like some confirmation from people who know what they are talking about, which is not me.
Thanks,
--Dan

Thu Nov 23, 2006 8:31 pm

I don't paint for a living but my understanding of "at the cap" means
the pressure reading with the trigger pulled.
Yes, it will drop, if it doesn't, your gun is plugged.

Thu Nov 23, 2006 9:35 pm

Each gun has a specific inlet pressure that will achieve 10psi at the tip. For instance, a Sata spray gun will require 50psi inlet pressure to get 10 psi at the tip. Having no more than 10psi at the tip is one of the main requirements to be HVLP. What kind of gun do you have? I could problably tell you what inlet pressure you will need to get 8-10.

Thu Nov 23, 2006 9:43 pm

BIG MAC wrote: Each gun has a specific inlet pressure that will achieve 10psi at the tip. For instance, a Sata spray gun will require 50psi inlet pressure to get 10 psi at the tip. Having no more than 10psi at the tip is one of the main requirements to be HVLP. What kind of gun do you have? I could problably tell you what inlet pressure you will need to get 8-10.

Hey Big Mac, its a Devilbiss FLG3. So, I measure the PSI with the trigger depressed, right?
--Dan

Thu Nov 23, 2006 11:15 pm

Braukuche
I have the same gun as you. Everytime I use it, I end up setting the pressure around 35-40 psi and it seems to be about right. I dont know if its the correct way to tell but when I squeeze the trigger the pressure on the gauge drops to about 10. Also when spraying heavy primers it seems to work better if you raise the pressure by a couple of psi then use the adjustments to get the gun to flow right.... I know this isn't the right way to use a hvlp gun but I don't have a 1.6 or 1.7 tip for mine.
BTW
Devilbiss sells a kit that you plug into the cap and it has a pressure gauge on the end of it.

Fri Nov 24, 2006 8:17 am

Jeremy wrote: Braukuche
I have the same gun as you. Everytime I use it, I end up setting the pressure around 35-40 psi and it seems to be about right. I dont know if its the correct way to tell but when I squeeze the trigger the pressure on the gauge drops to about 10. Also when spraying heavy primers it seems to work better if you raise the pressure by a couple of psi then use the adjustments to get the gun to flow right.... I know this isn't the right way to use a hvlp gun but I don't have a 1.6 or 1.7 tip for mine.
BTW
Devilbiss sells a kit that you plug into the cap and it has a pressure gauge on the end of it.

Thanks for the info. I am using a 1.5 tip per the specs from PPG for the material I'm using.
--Dan

Fri Nov 24, 2006 11:11 pm

An flg3 will require 23psi inlet pressure to get 10 psi at the cap. When you plug your gun inline, your gauge should read line pressure. Pull the trigger on your spray gun and watch the gauge, it should drop to regulated pressure. Now just turn the knob until you reach 23psi. Always set your pressure with the trigger depressed, but to 23 psi not 10 psi.

Fri Nov 24, 2006 11:57 pm

BIG MAC wrote: An flg3 will require 23psi inlet pressure to get 10 psi at the cap. When you plug your gun inline, your gauge should read line pressure. Pull the trigger on your spray gun and watch the gauge, it should drop to regulated pressure. Now just turn the knob until you reach 23psi. Always set your pressure with the trigger depressed, but to 23 psi not 10 psi.

Thanks for the info, Big Mac.
--Dan