Viscosity of Ref. oil

Hi, I am new to this ocean of knowledge and experience.
I am little bit experienced in R11 centrifugal water cooled chiller operation and maintenance. Handled various breakdowns like bearing seizure due to oil failure, impeller eye bolts broken, impeller damage etc. etc. Repiared and reconditioned various parts and used.
Now, we are in the process of phasing out these units with R134a screw chiller.
Many questions are in mind. Over the time, I will be sharing those.

Why viscosity of refrigerant oil drops down so sinificantly immediately after use. ***** in oil brings down viscosity. But, even if ***** is driven out by moderate heating of fesh oil, viscosity is about 50 %.

The oil viscosity is reduced by a condition called "dilution". The way to reduce this by the method you mentioned; the oil must be warmer than the refrigerant saturated temperature (for the pressure of the refrigerant).

In a lot of systems it is not uncommon to provide a higher viscosity oil (when the oil is fresh). When the refrigerant is introduced into the system, the oil viscosity will be reduced close to the requirements of the compressor. In other words, the diluted oil has sufficient viscosity to provide adequate bearing and load support during compressor operation.

Thanks for your comments.
Let us consider a live example.
Viscosity of fresh York C oil at 40 oC is about 68 cst.
Viscosity of used oil ( hardly after 2 days use ) after taking out ***** by heating to 60 oC and measuring viscosity at 40 oC - 37 cst.
Why this happens ?

Quote:

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Originally Posted by Nirmalya

Thanks for your comments.
Let us consider a live example.
Viscosity of fresh York C oil at 40 oC is about 68 cst.
Viscosity of used oil ( hardly after 2 days use ) after taking out ***** by heating to 60 oC and measuring viscosity at 40 oC - 37 cst.
Why this happens ?

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Poor quality Oil:eek:

We have measured Reflo 68 after over a years running and the viscosity (from a lab) was just below 60 cst.
Mind you Reflo is a hydrocracked oil.

Kind Regards Andy:)

:confused: Thanks for your comments. I will take up with the supplier. If you have experience on oil behaviour in R11 centrifugal machine, kindly share.
Regards
Nirmalya

Please,
I need cross-reference oils york type L and other
One of your return