Hall Screw Oil Return Issues

[JP85]

Hi, I am having issues with a Hall Screw 2020 running on Ammonia. When compressor is running unloaded oil level in seperator is good, as soon as compressor starts loading up oil level in sperator starts dropping off untill compressor trips on low oil level fault. Once compressor is switched off the oil returns to seperator. the oil seems to be held up in compressor for some reason, any ideas?

[Tycho]

Do you have a picture of the compressor package/Oil separator?

I see this on some oil separators, when the compressor is on low load there will be oil on the max mark, but once it's running on full capacity the oil level will drop significantly.

Also a wet suction or rapid changes in the capacity can make the oil foam up and make the level switch drop, even though you have enough oil, especially on vertical oil separators.

[Greek_engineer]

send some photos.
probably problem with pressure equation between crankcase and separator.
for a particular reason the oil is transferred violently towards the crankcase when the demand for cooling capacity is high and the compressor pumps to a high degree.

[RANGER1]

Have heard of a few where internal ball bearing check valve in discharge has fallen out.
Held in by circlip or similar
Observed poor performance & little ice on suction line

[RusBuka]

Discharge pipe go high and without oil traps? )))

[JP85]

I will try get some photos over the next day or so. The capacity on this compressor is normally fairly stable as this is a holding room, not used for pulling down product. We have two identical compressor skids on this site, but only one seems to be having this problem.

[Tycho]

I will try get some photos over the next day or so. The capacity on this compressor is normally fairly stable as this is a holding room, not used for pulling down product. We have two identical compressor skids on this site, but only one seems to be having this problem.

Followup questions:
Are the two compressor units connected on the same system (common suction and discharge),
-are these two compressors running on the same system?
-are the compressors running at the same time?
-are they connected to a common suction and discharge line?
-if they are not on the same system, are there any differences in suction pressure? (higher suction pressure on the problem unit?)
-is this something that has developed, or has it been a problem since it was installed?
-Have you tried charging oil while it was running, to raise the oil level during operation?


Looking forward to hearing from you