Screw compressor (ATLAS GA510)

[AndEdtec]

The compressor runs and makes air, so the suction box is open allowing air into the screw. Air filter is good. Seperator is good oil filter is good.

The problem is than when the compressor is unloaded the temp builds up and cuts out on over temp. When the compressor is loaded it seems ok and holds its temp.

So I think the oil is not going through the cooler? But why?
Is there a bypass valve?

A friend said it sounds like low sump pressure! But I haven't got the knowledge on compressors to fix it. Please help me find the info I need.__________________
Andy :-)

[Andy]

The compressor runs and makes air, so the suction box is open allowing air into the screw. Air filter is good. Seperator is good oil filter is good.

The problem is than when the compressor is unloaded the temp builds up and cuts out on over temp. When the compressor is loaded it seems ok and holds its temp.

So I think the oil is not going through the cooler? But why?
Is there a bypass valve?

A friend said it sounds like low sump pressure! But I haven't got the knowledge on compressors to fix it. Please help me find the info I need.__________________
Andy :-)

Wouldn't know much about air compressors, but there should be a thermostatic valve to control the oil temp, these go faulty if overheated (wax element)

Kind Regards Andy

[NoNickName]

Insufficient water cooling or clogged intercooler.

[Mickvee]

I am not an expert on air compressors but have worked on them a little with engineers as thay have air dryers. From what I can remember thay have a thermostatic value in the oil curciut so when the oil is below 70 degrees the oil bypasses the oil cooler.
Maybe when air is flowing down the lines it has a cooling effect on the Air/Oil exchanger

[US Iceman]

I don't know anything about the screw compressor model you mentioned, however, I can tell you it can be common for the oil cooling load to increase on screw compressors when they unload.

The amount of air being compressed decreases as the compressor unloads. At the same time the amount of energy being added to the air (that is being compressed) increases at a very high percentage. This causes the oil injection temperature to increase (along with an increase in the required oil cooling load).

If the oil injection temperature increases, the discharge temperature will also increase.

I would investigate the oil cooler to see if it has a three-way valve that controls the oil flow into the cooler.

Does the compressor have an after-cooler? This may be part of the problem.

If the oil cooler is water cooled, does it have a water regulating valve to control the oil injection temperature?

[Andy]

Insufficient water cooling or clogged intercooler.

As Nick says fouling of the cooling surface is a good starting point.

Also check if it is water cooled that enough and cold enough water is going through the oil cooler

Kind Regards Andy

[md.tanwir]

Dear, I think that when the compressor is un loaded then there is little pressure built for the oil return, there fore the oil solenoid valve is not working properly, check it.Otherwise check the solenoid valve near the plate Heat exchanger or water cooled heat exchanger, whether it is working properly or not. I hope this will solve your problem

Have a nice day

[Tejbir Singh]

The compressor runs and makes air, so the suction box is open allowing air into the screw. Air filter is good. Seperator is good oil filter is good.

The problem is than when the compressor is unloaded the temp builds up and cuts out on over temp. When the compressor is loaded it seems ok and holds its temp.

So I think the oil is not going through the cooler? But why?
Is there a bypass valve?

A friend said it sounds like low sump pressure! But I haven't got the knowledge on compressors to fix it. Please help me find the info I need.__________________
Andy :-)

although I don't know much about the but it seems that 1) oil pump is not working
or
2)there is no oil pump
and oil is being pumped due to differencial pressure . either suction pressure is sucking the oil or discharge pressure is pushing the oil.

if its the second case its normal as you maybe running the compressor unloaded for a long time.

incase of first case get oil pump checked from a qualified person

Tejbir Singh