Pulsing Airstream

[buckey55]

I have a Craftsman 25 gallon, 1.6 hp compressor that I would like to use as an air source. I recently replaced the regulator due to its age and the fact that it was hard to adjust. The replacement regulator is a Craftsman part similar to the original with a built in particle and moisture trap.

I have sprayed acetone through a dual action Pasche and a DeVilbiss gun and both guns pulse. The pulse rate increases and decreases with pressure. The higher the pressure, the faster the rate.

Obviously, this is unacceptable for painting. Is this a feature of the regulator? Any suggestions?

Thanks,

Jeff

[ABD]

Never heard of pulsing with a comp that has a big tank...I'd guess it's in the regulator, something faulty ..But just a guess.

[buckey55]

It has got me confused too. The new regulator and the old one both do the same thing.

[Strictly Attitude]

make sure your fluid tips are tight they will cause that problem also

[AndyW]

All I can suggest is exercising the regulator a few times, wind it all the way up blat air through wind it down, could have an obstruction in the inlet to the reg, or are you using a manifold for your hose, it could be your hose as well as the problem has occured in both regs, the hose could be collapsing internally.

[buckey55]

Thanks for the suggestions. I believe the tips are properly adjusted, but will double check. I was wondering if the hose might be damaged. I will try and clear out all the lines if the main hose doesn't prove to be damaged. I guess the only way to clear the lines is to remove the regulator assembly and turn the compressor on.

I'll continue troubleshooting this evening when I get home from work.

Jeff

[buckey55]

Followed all the advice and am totally confused. I half to admit, I don't know what I am missing here and what to try next. I have to believe I am dealing with adjustments on both guns.

1) I took off the hoses and hooked the Pasche and the Devilbiss directly to the regulator. This eliminated the hoses and couplers. Tried a variety of pressures and gun adjustments. Both guns still pulsed.

2) Removed the regulator and attached both guns directly to the tank. Pumped the tank up to approximately 40 - 50 psi based on run time. Both guns still pulsed.

3) Pulled out a SCUBA tank and hooked up a bleed of the first stage high pressure and a regulator. Ran pressures between 30 and 60 psi on both guns and tried every conceivable gun adjustment. Both guns still pulsed.

4) Took both guns completely apart and verified they are squeaky clean and no ports are blocked or mechanisms binding. Hooked them both up again and both pulse.

Since I have two completely different sources I am no looking at the guns. I can definitely get the pulsing to vary on both guns by playing with the needle adjustments, but can not get the pulsing to disappear regardless of pressure settings.

The problem has got to be me and my ability to make proper adjustments to the guns. I am at a loss right now.

Jeff

[Frog]

VENTURI EFFECT your sucking air in through the nozzle assembly. Strip nozzles assemblies down and check for damage, clean and reasemble with some beeswax wiped on all threads. Dont over tighten.

[sharonsstudio]

either what Frog said.. or you may have a hole in your hose..

[buckey55]

The culprit with the Pasche brush turned out to be a cracked Aircap Body (as listed in the Pasche parts list). When tightened down, the crack opened up allowing air to back flow into the gun. The crack is not visible when the part is not on the gun, only when tightened down. I had a spare cap and it is not cracked. The gun does not pulse with this cap holding the Aircap and Needle in place.

I still don't know why the DeVilbiss gun is pulsing. I have to assume it is also related to the gun set up since the Pasche is working properly again.

Thanks to eveyone for your suggestions and help.

Jeff

[AndyW]

Nice to hear you have one going again, at least that eases the frrustration a bit.

[buckey55]

It sure is less frustrating and fun to get going again.

Thanks again,

Jeff

[JimmyG]

follow the same trail on your devilbiss Buckeye....

[buckey55]

Will do JimmyG. Now that I know what the mechanism is that caused the pulsing. I should be able to figure it out.

[danieljink]

VENTURI EFFECT your sucking air in through the nozzle assembly. Strip nozzles assemblies down and check for damage, clean and reasemble with some beeswax wiped on all threads. Dont over tighten.

beeswax? will that help with the hose? its leaking air. i was thinking of teflon. but wasnt to sure

[AndyW]

beeswax? will that help with the hose? its leaking air. i was thinking of teflon. but wasnt to sure

I would think Teflon on the hose connections, the beeswax is for the business end of the airbrush, for the fluid nozzle etc.