I was phoned last week by a site engineer who was having issues with his liquid ammonia pumps cavitating.
After much discussion, I asked whether he had been away recently?
As I was coming to the conclusion that his system was short of refrigerant
His stand-ins have caused issues before.
No! Was the answer.

"But I have changed oil" (Clavus 68 is no longer available as we have discussed before.)

"And I was oil draining for at least 4hrs the other day. I cannot remember when I last removed so much oil!"

When told what oil he had changed to the penny dropped.
In the past I have noted issues with Mobil Gargoyle oils.
Because they contain a cleaning agent for want of a better word. Which is very good at cleaning / scouring systems.

I have reached the conclusion that the new oil is flushing the old oil. With so much being drained that the surge drum working level has dropped to the point where the pumps are being starved of refrigerant.

I have suggested that more ammonia is added and see if the issues are resolved.

Has anyone else experienced similar?
It strikes me that changing the oil in any system can have a huge impact on how it performs.
Grizzly