Yammering noise when unloaded Atlas-Copco GA122 (30hp)

by GreyBear
(Seattle. WA)

Have an Atlas-Copco GA122 (30hp). Builds pressure just fine, and unloads at the correct set value. When it hits the unload setting (116psi) and starts dropping down to the load (112psi) setting, it "yammers" very loudly as it loads back up to the unload value - back and forth cycle, consistently - any thoughts?
__________________
Bill says...

Way back when, when cars had distributors and points, you could get point chatter when they didn't sit properly (worn). Sounds to me like you have something like this going on in your pressure switch.

After you cut off the power and dump the air, pull the cover off the switch and have a look at the points (where they connect when the switch pulls in). If they are worn or burnt, you need a new switch.

Cheers,

Bill




Comments for
Yammering noise when unloaded Atlas-Copco GA122 (30hp)

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Mar 17, 2011
 Yammering Rotary Screw
by: Anonymous

good evening Greybear. By the looks of your setpoints (116PSI unload and 112PSI Load) you are 'rapid cycling' the compressor, the minimum between setpoints is 10PSI, you are putting undue stress on the inlet valve opening and closing and it may be causing (pardon my language) a 'farting' sound when it loads. Get a service done - change air, oil, and air/oil filters to rid the unit of any undue pressure differential, adjust your setpoints. From there, check the sizing of your storage, when running a rotary screw compressor in 'load/unload' the larger sized tank the better.

As for the yammering noise, my best guess is that the you have a 'cavitating' airend when the unit unloads - this is air sneaking past the inlet valve or past the shaft seal causing a pressure difference in the airend when there is no load on the unit.

Hope this helps

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