Flushing and Draining AAA Fluid Hoses

How to get hoses clean and prepped for the next day's work. January 27, 2007

To those who use the Kremlin Airmix and other AAA pump style systems, how do you purge the material out of the fluid lines before cleaning? With our old pressure pot system, we would drop the pressure from the pot and cover the tip with a rag and trigger the gun, forcing air to blow the material back into the pot. Is this possible with the pumps? It would seem a waste to just wash out with thinner without draining the fluid line in some way.

Forum Responses
(Finishing Forum)
From contributor G:
Are you using post-cat or pre-cat? Because when we used pre-cat, we would leave the paint in the gun all week till Friday, then turn the fluid pressure down to about 15 to 20 psi, then pump the excess back into the can, then turn fluid to 0 when the majority of the paint was out, then put the feed line into thinner bucket to flush. Now with post-cat, you can't save the paint, so it just goes into 45 gallon drum for Safety Clean to pick up.

From the original questioner:
We are using post-cat, so we need to clean out the lines for even short shut downs. Can you just pull the pickup out of the material and run the pump till the line is dry? I was/am reluctant to do that, as it seems like it would be hard on the pump.

From contributor T:
I use a C14-AAA pump system from CA Tech. Standard purging is done after every day's use. What I do is: Move the fluid siphon hose over to a bucket of wash lacquer thinner (if you're spraying pre-cat or post-cat, that is). Remove the cap and tip. Turn the fluid pressure down to near nothing so you only get a very slow piston movement when triggered. Aim the gun tip into your material can and start spraying what is remaining in the fluid line back into your material can. The pump will speed up slightly (due to it pulling thinner, which is less viscous, so requires less work of the pump) and your spray out of the gun will sputter a little. When that happens, aim your spray back into the thinner bucket/can, as this is now thinner flowing through the line. Keep the trigger held for a minute or so (basically you want 3 passes of thinner through the fluid hose). I'd label that can of thinner as "dirty thinner," which means it is what you'll use to basically wash the lines out.

The final step is to put the siphon hose now into fresh, clean thinner and let it flush through the line one time so you are leaving only clean thinner in the line. Then leave the fluid siphon hose in the clean thinner, leave the tip and cap in a small cup of thinner and you're done for the day. Don't forget to leave the piston in the down position so air doesn't dry up the finish that is on it, otherwise it'll be very crusty the next day and get pulled down into the pump. Not good. The next day, or when resuming spraying, just throw the siphon hose into your new batch, spray the thinner into your dirty thinner bucket and when it starts to spray material, you're good to go - clean the tip and cap and reassemble and have a productive day! I do this daily and the baby is spraying as good as the first day I got it.

From contributor G:
Contributor T is totally correct. One other thing, you don't need to flush for short shut downs, only when you clean up for the end of the day. Just leave the lines under pressure - it won't harden up, just clean the end of the tip after a shutdown period, make sure the agitator is working and start spraying.

From contributor G:
Forgot to mention: never drain the lines dry, always have either thinner or paint in them!

From the original questioner:
Thanks - that is just the kind of info I needed.