constant oil filter changes

[claude11]

I've just started as chief engineer in a new plant . The others have told me the change the oil in a FES compressor at least once a year and usually change the filters 2 - 3 times each year . the are using a ESSO mineral oil polar wf 55 . The manufacter calles for FES #2 would that make a difference ??

[US Iceman]

Hi,

My recommendation is to use oil sampling and analysis to determine when the oil should be changed. This process helps you to track the oil quality over time and also allows you to monitor the particles suspended in the oil.

The compressor manufacturers oil recommendations should always be followed. Do not depend on an oil supplier to tell you his oil is a good as, or identical to, what the manufacturer recommends.

A second consideration is to check the oil filter types. Changing oil (when required by analysis) is only a portion of the requirements. The ability of the filter to collect small particles is what protects the compressor bearings.

I don't know off hand what FES recommends, but it might be a good idea to see if they offer a "better" oil filter.

[absrbrtek]

I agree with US IM. Change the oil on analysis, not because thats the way they did it in the past. I don't know the size of your FES machine, I have done some 300 gallon oil changes on them. A real waste of time and money if its not needed.

As for the oil filters, if your not seeing any pressure drop why change them? The FES oil filters I've changed were pretty large in size and could hold alot of particulates. I would change the filters once a year, when the oil analysis dictates an oil change or when theres excessive pressure drop accross them. JMHO

[US Iceman]

One of the issues is not only the volume of particulates that can be held in the filter, but the size of particles allowed to pass through the filter element. Both are critical features.

In this day and age anyone who says the oil should be changed only on some arbitrary time value is probably selling oil himself.

If the oil is filtered properly and is not contaminated by anything, then why change it??? The oil analysis will prove this...

[NH3LVR]

I agree totally with the other guys. Why change oil if an analysis says it is good?
Oil filters do tend to clog rather rapidly at the end of their life. An example of this is when you start the machine with colder than normal oil and get a high differential reading.
FES ( a great company) did have some filters come through with a smaller micron rating than normal. These caused some problems with rapid clogging.
Changing the filters 2-3 times a year, unless you have a lot of contaminates in the system is a waste.
Beware the supplier who brings you a colorful brochure on the "brand new" oil that will solve all your problems.

[US Iceman]

The micron rating of the oil filters is a tricky subject. I have used some absolute filters which means the filter will NOT pass any particle larger than the specified particle diameter the filter was rated for.

On one job in particular it was not much fun. The system was a field erected R-22 system spread out all over the facility. Lots of debris and weld slag in very large pipes.

On start-up we were changing oil filters about every 2 hours or so after a couple of days. This lasted for almost 3 days until the amount of junk started to become reduced to a more livable level.

After this period had passed the oil filters were only changed about every 6 months, but the oil was not changed until the oil analysis dictated it.

Some filters are rated on a "nominal basis". The micron rating for these simply mean the given particle size is the average diameter that will pass through the filters.

Here is a good link to read.
http://www.pall.com/hydraulic_3779.asp?level0=2

[US Iceman]

I found some other useful information...

http://www.filtrationtips.com/2005_09_08.htm

http://www.machinerylubrication.com/...?articleid=704

http://www.oilanalysis.com/dictionary/default.asp

http://machinedesign.com/BDE/FLUID/bdefp2/bdefp2_1.html

As you can see after reading these, there is a lot more to the subject of filtration than meets the caual observation.

This is very important for new machines before the bearings get scuffed up. An older machine with many hours of operation on it probably already has the damage done.

[claude11]

The oil we're using is Esso polar wf55 a mineral oil . FES calles for a iso paraffinic oil . could this be the problem

[US Iceman]

could this be the problem

Well I have to admit I am a little msytified...what problem?

Is this question related to the oil filter changes?

Are the filters being changed due to high pressure drop across the elements, or just being changed randomly 2-3 times a year?

[claude11]

they change the filters 2 - 3 times a year due to high pressure drops . when the filters are removed they are clogged and some times compressed ( squeezed together from the oil pressure). The oil looks like extremely black coffee.
My question is : Should a 500 HP FES screw ammonia compressor need a complete oil change every 8 months of operation and 2 - 3 oil changes a year or should I consider the oil the problem ( we use Esso Polar WF55 , FES recommends FES #1
By the way thanks for all the advice

[US Iceman]

Should a 500 HP FES screw ammonia Compressor need a complete oil change every 8 months of operation and 2 - 3 oil changes a year...

My answer would be NO, IF, everything else is OK. Have you cut the old filters apart to see what kind of junk has been found?

If the filters are collapsing, it might be from debris in the system, or a reaction to changing the oil causing the elements to swell and then collapse.

I think I would start by investigating the differences between the two oil types (using an oil analysis lab) and what is occurring within the old filters being removed. Again, a good lab can provide some assistance on particles and type of materials being filtered out.

One thing I should also mention: If the system is older and originally had recips and rotary boosters you might have a lot of junk out in the piping. The oil filters on screw packages could be compared to a vacuum cleaner trying to clean all of the junk out of this system.

I've seen this before on the above scenario. Once you get the system cleaned up, the oil filter changes are drastically reduced.

[JoeK]

HI!!
I must agree that oil samples are the way to go. I did not pick up on what compressor is on the FES Pack. I ran a system with 10 FES units using Hall-Mono Screws and only carried out complete oil change when we changed oil suppliers. I would say you must not waste money on synthetic oils but use a blended semi-synthetic for AMMONIA COMPRESSORS i.e. CP-1008-68 by CPI Engineering Services, INC. We have had very good results by changing plants with both screw and recips to this oil

[TXiceman]

Claude11, did you ever get your oil issues cleaned up? If your oil is black, you do have a contaamination problem in the system and need to address that.

Oil should be monitored with at least quarterly oil analysis and FES does offer this service. Have you checked your system for water? How old is the system?

Ken