- Question Title: Atlas Copco GA5 loading valve problem
- Asked by: Guest
- Asked On:
- Answers: 4
Hi.
I have spent a lot of time trying to figure out the root cause to my compressor problem, but without luck. So I´m now turning to this forum for help.
The inlet valve does not open fully when magnetic valve activates. It sort of hesitates and this results in very little or no air supply under 4 BAR, over this pressure it works fine.
I have changed the wear parts in the loading valve assembly and checked the function by using an external pressurized air supply, and it opens fully when pilot air supply to loading valve exceeds 4 bar. So there is no fault to magnetic valve or loading valve assembly as far as I see.
I kind of think that the pilote pressure needed to open the intake valve is to low? This pressure pipe is taken directly from the secondary side of the screws.
To build more internal pilote pressure I also tried to increased the springforce on the check valve on outgoing air from the compressor unit, but without any improvements. Oil level is OK and I have tested both lower & higher levels without any noticeable difference.
The compressor is pumping fine if I force open the intake valve.
I bought and rebuilt compressor unit a with new screw bearings a few years ago and it worked fine for two years before this loading valve problems began to be a big problem.
I would be grateful for some ideas as I´m at the end of the road here.
Thanks in advance
Thomas, in northern part of Sweden.
Answers & Replies
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Hi Thomas,
4 bar should be more than enough to operate the inlet valve. I think around 1.5 bar should already be enough to operate most inlet valves!
Since this inlet valves operates in the mode 'control pressure = open', 'no control pressure = closed'
It means that from completely dead startup (no pressure at all), there's a little by-pass hole so the compressor always sucks in a little air to built up the internal control pressure. Inlet valves that work with this system usually can operate at quite low pressures already.
Did you also check of there are any vent holes that are plugged? So that compressed air can move out of the other side of the control piston when it's needed.
Other than that, sometimes it's just bad luck and only a replacement of the whole inlet valve will fix it.
What make and model is this compressor?
Thanks, Cas
Sorry, I now see this is an Atlas Copco GA5.
From what year is this model, or what is the serial number?
Is this the older model with the separate solenoid valve, or is the solenoid mounted directly on the inlet valve?
Is the pilot valve OK. Is it not leaking internally, is the small spring there?
Test this: Apply control pressure and check the following (maybe remove the inlet valve from the compressor if it's easier):
Hope this helps!
Thanks Cas for some refreshing new ideas! The GA5 is a 1995 model with the solenoid directly on the intake assembly. It evacuates air end pressure fine when unloaded, but I will take a closer look at the own generated pilote pressure and if the small suction passage is open so that it can generate pilote pressure as intended. Very useful info that 1,5Bar should be enough for the valve to open fully. I will get back with some results later. The unit is a full featured one with air cooler so it is great when running. Thanks.
check minimum pressure valve, or any leakage sealing issue