Hard oil in ammonia system

Hi all,

This system has now been offline since November and we have been running temporary chillers at a stupid cost per week since then.

I was called by a customer who told me there plant had tripped on oil pressure fault, they told me there was no oil level in the sightglass of the compressor. They added oil and the plant ran happily for about 36hours.

The plant then tripped on oil pressure with what seemed to be 100% level in the glass, so curiosity got the better of me, I vented the compressor down and inside was a hard, wax like oil mixture. I spoken to the customer and they had put in Castrol 2284 instead of the Castrol 2294 the system uses. (it's an ammonia/propylene glycol PHE plant running 8 chill coolers [-6 glycol temperature])

Obviously I cleared as much out and both compressors have been taken away for inspection, I need to replace so much of this system now including separator, oil return pipe work, filters etc that I was wondering what caused it to happen in the first place.

I spoke to Castrol Technical who said mixing of those two oils would not have caused this problem, although mixing of oils is not recommended.

Any suggestions?

Hi Scotty.
I have not got access to all my data as I am working away, however as far as I can tell the 2 oils are not compatible with each other.
2284 being a Alkobenzene 68 and suitable for flooded evaps and ammonia.
2294 is a polyalphiaolefin and not suitable for flooded evap systems and I cannot see mention of it's use in Ammonia systems either.

I would assume you have created Waxing by mixing 2 incompatible oils?

For some reason I cannot load the data I have extracted from castrols site, however if you google the 2 you will see what I mean.

Grizzly

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