Help-oil life time

[Josip]

Hello friends :)

Please help me with some practical experience about oil life time.

How long (months, years, working hours) we can run compressor with (*****s: R22, R134,R....) without oil change.

Let's say compressor is industrial type (semihermetic-screw or piston, open-screw or piston) working 12-18 hours/day.

Difference between low and high stage, mineral or sintetic oils?

Any suggestion is welcome.

Best regards,

Josip :)

[afeef]

hi josip
there is spicific no. of hours of oil to be changed because of the working condition is different between cases, but the acidity of the oil can be measured to determin its condition.
in most cases 10000 hr. of working is acceptable to change refrigeration oil, thats be 4-5 years
regards
afeef

[Andy T]

Also depends on the size of the system, as in cost of breakdown due to dirty oil.On a large pack we would change the oil once a year as the cost of new oil was cheaper than the cost of repairing the system due contamination or component fault.Also you can never get all the oil out.So by an annual oil change you are forever diluting the bad oil from the system.Also by testing the oil for acid discolouration etc.You may spot other problems before they become a large fault.Also replacing the oil removes debris and moisture.On a smaller system with a way of extracting the oil.A visual inspection would let you know if it may need changing.If it is black or brown you should replace it.If it is black then also look for other faults like overheating or reed problems.On small systems with no means of removing the oil other than taking the compressor off then you would have to expect the oil to last the life of the comp.This is based on my experience of HCFC, CFC system.

[Johnny Rod]

Oil analysis is used in fridges, trucks, JCBs, all sorts of things, to keep an eye on the condition of the equipment but also to help determine service intervals - if it's running well and so the oil isn't getting a hard time, no need to change it yet and save yourself time and expense. Conversely if it's not, you get early warnings.

[US Iceman]

I recommend using an oil analysis program to determine the oil replacement. By regular use of oil analysis you can see the trend in viscosity reduction, acid or water content, wear metal particles, etc.

By trending the history of the oil over a period of time you can track when one of the parameters is reaching an unsuitable condition. The number of hours of operation does not reflect the actual condition of the oil.

I also recommend using an oil filter with an absolute micron rating as opposed to a nominal micron rating. A nominal micron rating is an average particle size, which means some particles may not be captured in the filter.

A word of caution about high micron filter ratings... A 10 micron absolute filter may collect particles very quickly and lead to nuisance oil failures. If the system is dirty the damage is already done. In this case, using high filtration elements may not provide substantial benefits.

The most benefit is gained when the high filtration elements are used at start-up and after.

Screw compressors can actually sweep a system clean of metal particles and other debris. If the oil filters on the screw compressor are a full-time filter and have an absolute micron rating the filters may need more frequent changing. However, this does not have anything to do with the oil quality.

I would also recommend a dual oil filter arrangement to provide the opportunity to change the oil filter without shutting down the compressors.

I also like the synthetic oils as they seem to be more stable over a longer period of use.

By using a high quality filtration system and good oil I can't see any reason why a screw compressor cannot last for 100,000 hours or more.