Rust in Ammonia Compressor???

[lonestar]

Hello all. I am writing to understand what could be the cause of a darkening of the internal parts of an ammonia compressor. The darkening is almost a rust like color. The ammonia is not 100% free of water(like most big industrial systems) and the oil running in the system is a Synthetic PAO/Alkybenzene blend. The oil has 6000 hours on it and the machine came down because of a bearing noise. In fact, the alignment of the machine was off 1 millimeter.This is the main problem but the secondary problem is that the oil is in very good chimacl state apart form being dirty, but the interior parts of the machine are rust colored. This coloring has appered again before in other machines without any bearing damages and has been explained that a coloring of the surfaces could take place because of a reaction between the oil and water and ammonia. I would like any insight for any other tech person. One last note the coalesecent filters were opened and were full of this rust like color. This could depend more on the rust being carried with the ammonia other than it being carried in the oil.

I have many photos and oil analisis if necessary.

Thanks for any help Lonestar

[Segei]

What kind of machine do you have? How old is the plant? For the rust you need air.

[subb-zero]

How sure are you, you haven't got water in the system water could also cause that as there is oxygen in the water.

[RANGER1]

Why are you using that type of oil ?
I dont know any details of it but never heard of it on ammonia .

[josef]

Water

[shanmug71]

Please inform what is the percentage of water content in the oil as per analysys.Have you checked moisture content in Nh3.

[Grizzly]

Why are you using that type of oil ?
I don't know any details of it but never heard of it on ammonia .

Hi Ranger.
There are several of these synthetic blends around and are becoming quite popular.
There is still a lot of the old 68\ mineral around.
But pao and ap oils are here to stay check out Mobil
for instance.
Cheers Grizzly

[Magoo]

Had a similar problem with a reasonbly new system, came from pipework stored outside uncapped, then installed. Was literally rust scale. Oil was synthetic SHC 226 mobil. Very expensive clean up cost. The oil had a red tinge look about it.

[tL9f8G2NBFX9bdh]

Check the auto-purger. It may need a tune-up. It's nearly impossible to get %100 of the noncondensibles out of a large system, but well kept auto-purgers do their best to protect the system.

[Magoo]

Hi tL9-----
I agree that auto-purgers are the greatest things since sliced bread, but they will not remove rust contaminates from a system

[subb-zero]

I agree with magoo they only remove non condensables not water (benji) it only there to prevent high head pressure when air is present, to save on energy.

[RANGER1]

You can get auto air purger with auto water still from hansen technology .