Lube oil for -40C application using reciprocating compressor & Ammonia refrigerant

[sandybapat]

Dear all,

In India in the food industries, use of two stage reciprocating compressors and Ammonia refrigerant for -40C evaporation temperature for various freezers is very common.

The compressor manufacturer (Kirloskar) recommends synthetic oil, however majority of the food industries are using Mineral oils having pour point around -25C for many years. The data sheets of these oils are attached for ready reference.

98559856

I wonder what must be the effect of mineral oil on following which these Food Industries may not be noticing?

1. Compressor maintenance cost
2. Evaporator performance

I would like to have comments from the forum on this aspect and would like to know following in case any of these industries opt of change over to synthetic oil:

a. Procedure for changing the oil
b. Precausions to be taken while changing the oil.
c. Whether change over will reduce the maintenance cost and improve the efficiency of the evaporators?

Sandybapat

[Brian_UK]

What refrigerant is being used?

[sandybapat]

Brian

I have mentioned Ammonia refrigerant already.

Sandybapat

[spare_parts]

SUNISO 3GS is OK oil.

[RANGER1]

Sandybapat
I would suggest main reason for using mineral oil is cost.
If compressors throw over a bit of oil then it may cost around 2 to 2.5 times the price.

New oil would have to be checked for compatibility which is up to you & supplier.
We are not familiar with your oil & are only giving broad answer to your questions.
Usually going from mineral to synthetic is better than synthetic to mineral.

Usually try & change oil in compressors, mop out sumps & drain any other components in the system as possible.

You may find strainers & filters could block up initially. everyone will panic of course so have a supply handy & labour to do it.

Synthetic oil is better but there is some good mineral oils as well as blends.
Some are called "cracked" which are better.
Synthetic oil behaves better if you have air in system, as it does not break down like mineral oil.

Theoretically evaporator performance should increase but no guarantee's, same as compressors.

Good efficient oil seperators is best in all circumstances.

Don't rush into it until you have done your homework & maybe talk to someone who has done it already if possible.

We have done it numerous times with no real problems except filters blocking up for awhile.

[sandybapat]

Thanks Ranger1

Is mineral oil technically correct for use on -40C system with Ammonia and piston compressor?

Sandybapat

[RANGER1]

Thanks Ranger1

Is mineral oil technically correct for use on -40C system with Ammonia and piston compressor?

Sandybapat

Yes if correct one is selected.
The compressor is not really affected, only evaporator with pour point etc.
We have used Suniso 4SA & 4GS. The 4SA is not perfect but the price is!

We tend to use a lot of American (CPI) & German (Kluba)oil these days & Suniso.

It seems that a lot of oil is rebranded, so sometimes it can be a very common oil with different name.

[sandybapat]

Thanks Ranger1 for the information.

[Brian_UK]

Brian

I have mentioned Ammonia refrigerant already.

Sandybapat
My apologies, I misread your post.

[sandybapat]

Dear Brian

Your views on this query will be very useful for me.

Sandybapat