LVLP adjustment

[islandjj]

I've just brought a LVLP gun. I'm spraying high build primer, I set the gun pressure to 22 psi.
When I spray for the first few seconds I get a reasonable volume of paint then I get less paint delivered. I've set the regulator with the trigger pulled. The pressure does drop significantly when the trigger is pulled, but down to 22psi as set.

I'm thinking that the viscosity is too high, the paint in the gun chamber being delivered then less as more paint has to get through the inner filter, or could it be the air plug at the top of the pot, or do I need to up the pressure ?

The supplier said i didn't need to thin the paint but I'm not so sure. Any advice would be much appreciated

 

[richie00boy]

Unless you have large bore hose and only a couple of metres max between the gauge and gun, you are probably below pressure. You should have a gauge on the gun really.

Also presume you have 1.8mm tip if you are spraying primer. If it'd smaller that will be an issue too.

 

[pedrobedro]

Are you letting air into the pot via the plug in the lid ? If not you will get a vacuum and stop the paint flowing.

 

[islandjj]

Thank you for the prompt replies.
I've got a 1.8 tip and the gauge is on the gun. What should I set the regulator on compressor at should it be max ?. I'll try taking the plug off the paint pot and see if it makes a difference. I'm trying to avoid using thinner

 

[richie00boy]

If you have no air hole in the lid then that is probably the problem!

I run compressor regulator about 60psi then a filter regulator near the gun set to what the gun needs via a gauge on the gun.

 

[islandjj]

If you have no air hole in the lid then that is probably the problem!

I run compressor regulator about 60psi then a filter regulator near the gun set to what the gun needs via a gauge on the gun.

Thanks, I've a regulator and gauge on the gun , I'll set the regulator on the compressor at 60 psi. Do you set the pressure at the gun with the trigger pulled ?

 

[steveo3002]

look up a tech sheet for what you are spraying , most stuff needs thinning

 

[pedrobedro]

look up a tech sheet for what you are spraying , most stuff needs thinning

As above you need the correct mix, unless it is supplied ready to use it will most likely need thinning. I have had "ready to use" cellulose paint that needed more thinners before and high build primer I've used has always needed thinning.

 

[islandjj]

can I use standard cheapo thinners with high build ?

 

[steveo3002]

yeah it should mix with standard thinners , try to avoid the gunwash spec stuff if you can

 

[richie00boy]

You should use 2k thinners with 2k products. A 5 litre tin of basic 2k thinners costs about the same as cellulose thinners, why risk it?

Do you really have a regulator on your gun? Those blocks with a gauge attached are just an air choke not a regulator. So you don't have a filter regulator on the wall or even screwed to a bit of wood?

 

[keithski122]

Thanks, I've a regulator and gauge on the gun , I'll set the regulator on the compressor at 60 psi. Do you set the pressure at the gun with the trigger pulled ?

Yes, with the trigger pulled.
If you have a pressure adjuster on the gun set the compressor at max and reduce at the gun with the trigger pulled.

 

[the snooper]

the reason the gun is doing this is airflow, while you are not using the gun the pressure will build and you will get more paint flow initially, I would be looking at the regulator, is it a cheap one ? if so some have a terrible cfm rating

 

[islandjj]

I've got a regulator , water trap onthe wall, it was quite cheap. Is there a way of approxamatly checking the airflow ? (I've also got quite a long hose to the gun)

 

[the snooper]

I've got a regulator , water trap onthe wall, it was quite cheap. Is there a way of approxamatly checking the airflow ? (I've also got quite a long hose to the gun)

if you have a regulator on the gun you could try removing the first regulator and see how it performs if its better you have found your restriction

 

[islandjj]

Taken the longer hose away and regulator. Not sure if the compressor is keeping up with the gun as it gradually loses pressure. The gun needs 4.5 cfm at 22 psi but the compressor delivers more than this. 50 litres 2.5 HP. I've another compressor which I was using for the air feed mask , I could try coupling them together is this possible ?

 

[richie00boy]

I use a 3HP 50 litre compressor with a similar gun and also one that takes more air. You should be fine. Check your gun for air leaks. Sometimes the nut on the trigger comes loose.

 

[the snooper]

Taken the longer hose away and regulator. Not sure if the compressor is keeping up with the gun as it gradually loses pressure. The gun needs 4.5 cfm at 22 psi but the compressor delivers more than this. 50 litres 2.5 HP. I've another compressor which I was using for the air feed mask , I could try coupling them together is this possible ?

did removing the regulator cure your initial problem ?

 

[RaceDiagnostics]

Taken the longer hose away and regulator. Not sure if the compressor is keeping up with the gun as it gradually loses pressure. The gun needs 4.5 cfm at 22 psi but the compressor delivers more than this. 50 litres 2.5 HP. I've another compressor which I was using for the air feed mask , I could try coupling them together is this possible ?

Yes you can couple them together, that's what I did, I also coupled the electrics but that's not really necessary.

 

[islandjj]

did removing the regulator cure your initial problem ?

Its improved it, there was also a small tap on the compressor which i opened right up , the compressor is just about keeping up but its running all the time so presumably this will cause water problems !