Odd Oil Situation

I'm having an oil situation here at a facility and wondered if anyone could throw some light on it.

In one of our facilities, we've seen viscosities between 85-91 for several years from our compressor oil. The oil is Clavus 68 from Shell. When I test it new, I get a viscosity in the 65 range. However, all six of our compressors regardless of duty have oil viscosities in the 90 range.

What could be causing this? I am not seeing this increase in viscosity in the other facilities although none of them:

1) Run anywhere near as hard
2) Run in a vacuum
3) Are using the Shell oil

We use an autopurger - we routinely test the oil and have found no contamination at all. Of course, we have also seen no sign of anti-wear additives in the oil either.

I understand that the recommendation is to replace oil when it varies 5% from the initial viscosity. That's a very expensive proposition when you are talking about 6-700 gallons of oil.

I think what you are finding is typical of mineral oils and believe this is due to what are called the "light-ends" of the oil. As the oil is used it tends to de-gas into various hydrocarbon vapors. This process causes the remaining oil to increase in viscosity.

On the fully synthetic oils this issue is not found (as best as I can remember). As a result, the viscosity index remains stable through temperature changes and longer life.

From conversations I have had and am trying to remember this is where the recommendations come from for more frequent oil changes, when mineral oils are used.

I prefer the synthetic oils myself because they seem to work better and last longer. And yes, they are more expensive but it is also important to look at long term effects also.

If I missed something.... I'm sure someone will correct me or add to the explanation.;)

Hy,
in my country (Brazil) we are having problems to find an PAO oil. It's international problem? Does anyone reard it ? Regards!

I am seriously considering trying Royal Purple Uni Temp synthetic. They are claiming a 10% electricity reduction and are willing to provide a logging meter to prove it over several months.

More info: http://www.royal-purple-industrial.c...dsi/utemp.html

Has anyone used this?

You need to talk to CPI in Midland, MI. They are the oil suppliers used by Howden, Frick, FES, & Vilter. That should speak volumes on who trusts who.

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Originally Posted by brian_chapin

I am seriously considering trying Royal Purple Uni Temp synthetic. They are claiming a 10% electricity reduction and are willing to provide a logging meter to prove it over several months.

More info: http://www.royal-purple-industrial.c...dsi/utemp.html

Has anyone used this?

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Hi, Brian.
I'm very sceptical about 10% of energy savings. In energy savings 10% is a lot. This is my fist concern.
Second is logging power use for several months. This is fundamentally wrong, because a lot of variables have influence on these numbers. Certainly, we all interested in energy savings on long run. However, correct energy comparison should be done within short period of time to minimize fluctuation of refrigeration loads and ambient condition.
In your case, choose 2 identical compressors operating in parallel and run them at 100% load. If they have port sides, close them. Compare power use. It should be equal or close. Change oil for one of them and compare power use again. This is correct comparison. Don't pay for this oil if energy savings less than 10%. Why do they want to log energy use for several months?

When I worked for one of the large ammonia compressor manufacturers we were approached by this firm to recommend their oil and additives. Our answer was always NO.

As a manufacturer you become responsible for all claims (yours or others; valid or not). This results in the manufacturers having to spend a lot of time investigating why the product did not work and why they will not honor a warranty claim. In some cases the manufacturers may tell you the warranty is void if other oils are used, than those recommended.

Sergei touches on some of the aspects of energy savings. All too often energy analysis can be a liars game. Any assumptions made on why the energy increased or decreased are often not correlated to the actual operation. As a result, the head pressure could have decreased for 3 months, which could save a lot of energy. However, if the oil additive is added during this time someone can claim the savings as their own.

If you want to save energy; modify how the plant & system is being operated. That is where the energy costs are. And... you have more control over this aspect and absolutely none with any additives.

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Originally Posted by US Iceman

If you want to save energy; modify how the plant & system is being operated. That is where the energy costs are. And... you have more control over this aspect and absolutely none with any additives.

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We've already picked all the low-hanging fruit off the energy savings tree.

I have several years of data logs for my compressors and a very good idea of what they are costing us in electricity.

My concern with our current oil (and all of these compressors are way beyond warranty) is that its pour point is -30f and we are running our boosters at -45f. I imagine that the oil is a sludge at that temp and we do often have issues attempting to start idle ammonia pumps until we warm them up and drain a small amount of oil out of them.

Brain,
PLEASE do not use the royal purple! I had a boss in a past life that sold this to one of my very good and large customers. I was not happy about this and soon found major issues. The worst was on a Frick RXF101. It was in a hydrogen plant. We had three failures in 9 months. Frick would not honor the warranty due to the royal purple. We also added it to the refrigeration machines. This stuff is probably great for cars or whatever but not refrigeration compressors. After the first failure we did not blame this stuff but after the second we did and removed it. The damage is already done at this point. Imagine how hard it is to get this garbage out of the package. The third failure happened after the oil change. After all of this I will say the package was replaced but not by us. They have never worked in that large group of facilities again. This incident prompted Frick to do studies on it and it was then added to the "band products list".

Low hanging fruits.
I think that this is optimization of refrigeration plant operation. This is the best way to save energy. I think that every refrigeration plant has great potential in this area of energy savings.
It looks like low hanging fruits. We need 2 simple steps to optimize operation of our plant.
Step 1. We should know the optimum set points. Unfortunately, majority of refrigeration plants operate at wrong set points, because we are guessing about them. These points are head pressure, suction pressure, frequency of defrosting and etc.
Step 2. Implementation of optimum set points can be wrong as well. Optimum head pressure during winter operation well below 100 psig. However, many people don't know how adjust hot gas defrosting at low head pressure.

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Originally Posted by brian_chapin

...we do often have issues attempting to start idle ammonia pumps until we warm them up and drain a small amount of oil out of them.

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Do these pumps have shaft seal heaters and are they wired up? Some of the pumps have these and are required.

When you say running at -45°F is this the compressor suction saturation temperature or the evaporating temperature? And, why are you running this low?

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Originally Posted by brian_chapin

We've already picked all the low-hanging fruit off the energy savings tree.

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What do you consider the low hanging fruit Brian?

If you had to guess, what is your energy reduction in a percentage that you have gained?

Sergei is talking about all of the right topics.

Companies that offer monitoring equipment often don't know what their product will do and use the owner as a guinea pig.

Considering the risk, I wouldn't use any oil that is not specifically approved by the compressor mfgr.

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Originally Posted by US Iceman

Do these pumps have shaft seal heaters and are they wired up? Some of the pumps have these and are required.

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No they do not.

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Originally Posted by US Iceman

When you say running at -45°F is this the compressor suction saturation temperature or the evaporating temperature? And, why are you running this low?

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We are running that low because the low side is a large hardening freezer for ice cream. My evap temperature and suction temp are within an inch or two of each other since it's a pumped recirc system.

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Originally Posted by US Iceman

What do you consider the low hanging fruit Brian?

If you had to guess, what is your energy reduction in a percentage that you have gained?

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Standardizing pressure settings, vfd's on the condensers and larger air units, sops show pressures which are checked often, replaced loads of faulty pressure regulators & leaking hot gas valves, added floating head pressure. We moved 65 tons of load from our low side to our high side (like we needed -45 suction to make ice!?). I can think of thousands of little improvements we've made too. We've documented energy savings in excess of 10% already and we added 60 tons of load during that time.


My current oil is not working - again I am seeing viscosity at 90+ when I should be seeing 65. I've seen several recommendations for synthetic oil and thought this would be one to try out. My compressors are not under any warranty. We have very low oil carryover - I think we drained a total of 100gallons of oil last year from a 1500bhp 6 compressor two stage system that runs nearly constantly.

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Originally Posted by Don Davis

Companies that offer monitoring equipment often don't know what their product will do and use the owner as a guinea pig.

Considering the risk, I wouldn't use any oil that is not specifically approved by the compressor mfgr.

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Since the link I provided has a list of 30+ compressors this has been used on, I don't see the relevance.

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Originally Posted by brian_chapin

No they do not.



We are running that low because the low side is a large hardening freezer for ice cream. My evap temperature and suction temp are within an inch or two of each other since it's a pumped recirc system.


Standardizing pressure settings, vfd's on the condensers and larger air units, sops show pressures which are checked often, replaced loads of faulty pressure regulators & leaking hot gas valves, added floating head pressure. We moved 65 tons of load from our low side to our high side (like we needed -45 suction to make ice!?). I can think of thousands of little improvements we've made too. We've documented energy savings in excess of 10% already and we added 60 tons of load during that time.


My current oil is not working - again I am seeing viscosity at 90+ when I should be seeing 65. I've seen several recommendations for synthetic oil and thought this would be one to try out. My compressors are not under any warranty. We have very low oil carryover - I think we drained a total of 100gallons of oil last year from a 1500bhp 6 compressor two stage system that runs nearly constantly.

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Hi, Brian.
Don't take it personally. I found that many end users improved operation of their plants and believed that this is the optimum operation.
1. Standard pressure settings. Probably, the settings like for majority of the plants. You need optimum settings, the best for your plant not for other plants.
2. VFDs. Settings of these VFDs are very important. The same VFD can give you more energy savings with different setting.
3. Floating head pressure. Do you really need it? This feature is useful for refrigeration plants with significant fluctuation of refrigeration loads. As far as I understand your plant doesn't have this fluctuation.
In energy savings is very important to use existing features efficiently. Can you give us more information about your head pressure? What are the settings? When and how do change these settings?

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Originally Posted by brian_chapin

We are running that low because the low side is a large hardening freezer for ice cream.

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OK, what happens if you raise the suction pressure 1 inch of vacuum? What happens if you raise it another inch?

I have seen a lot of locations where the suction pressures are much too low because it is assumed colder temperatures are the only way to cool something.

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Originally Posted by brian_chapin

We've documented energy savings in excess of 10% already and we added 60 tons of load during that time.

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What would you say if I mentioned some facilities have achieved reductions of up to 50% over an annual period? There are a lot dependencies in this value, location being one of them...

Refrigeration systems have built-in barriers that prevent them from being operated in an optimum manner. Sergei and I have had some running discussions about this in the past, but I think we both agree; each system is different & a lot of things affect the energy use.

Back to the oil issue...

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Originally Posted by brian_chapin

I think we drained a total of 100 gallons of oil last year from a 1500 bhp 6 compressor two stage system that runs nearly constantly.

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OK, how much oil was put into this same system during the same time?

Changing oil can be an interesting affair. Some shaft seals particularly in older machines can assume a seating position after years of wear. Changing the oil to a different type can introduce issues of shaft seal leaks, so you might want to be prepared to change the seals and oil filters & coalescing elements (they have rubber O-rings too).

I have had very good luck with CPI oils. Using a fully synthetic oil designed for low pour points is one issue. These oils have a good viscosity index which means the oils are very stable. The down side is the cost. However, I have always said it's the long term costs that matter, not the initial cost (within reason of course).

Trying to justify changing the oil on energy reduction would be a giant leap into fantasy if I were asked.

However, if you were to say; I want to review some oils to reduce the inherent operating issues we face on a daily basis (refrigerant pumps starting or oil draining) then you might have a case.

From my experience I have heard of more horror stories related to oil than just about any other single topic.

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Originally Posted by brian_chapin

Since the link I provided has a list of 30+ compressors this has been used on, I don't see the relevance.

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A marketing brochure that says it has been used on 30+ compressors (does it say successfully?) is not too much of a recommendation to justify placing yourself in the position of taking ownership of someone's product. Ask them for references; names and phone number you can call to verify the purported claims.

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Originally Posted by brian_chapin

My current oil is not working - again I am seeing viscosity at 90+ when I should be seeing 65. I've seen several recommendations for synthetic oil and thought this would be one to try out. My compressors are not under any warranty. We have very low oil carryover - I think we drained a total of 100gallons of oil last year from a 1500bhp 6 compressor two stage system that runs nearly constantly.

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Have you tried different companies for your oil analysis? And is this company trying to get you to change oils? It would be interesting to see the same oil sample given to 2 or 3 differnt companies and see how they compare.

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Originally Posted by nh3wizard

Have you tried different companies for your oil analysis? And is this company trying to get you to change oils? It would be interesting to see the same oil sample given to 2 or 3 differnt companies and see how they compare.

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Actually, I tested it at three different companies with nearly identical results.

I contacted this oil supplier while researching possible replacements for our clavus 68.

I'm not sure which oil to go with - but I know that using a straight mineral oil with no additives (from the manufacturer) isn't working for us.

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Originally Posted by Sergei

Hi, Brian.
1. Standard pressure settings. Probably, the settings like for majority of the plants. You need optimum settings, the best for your plant not for other plants.

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Our setpoints have been picked through multiple trials - we started at what we were told was normal and then worked to maximize efficiency.

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Originally Posted by Sergei

3. Floating head pressure. Do you really need it? This feature is useful for refrigeration plants with significant fluctuation of refrigeration loads. As far as I understand your plant doesn't have this fluctuation.

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We actually have a fairly large fluctuation in load. We have three large -20 storage freezers, a hardening freezer, three ice cream freezers, two bulk ice making machines, and a pair of plate&frame water chillers. I can usually tell you what production equipment is running by the sound level in the engine room.

The floating head simply moves my condensing pressure based on wet-bulb. Being in the northeast we get some bizarre temp/humidity fluctuations and since I don't feel like having someone at the control computer all day it makes life easier to have that automatically controlled.

Sadly, due to system design I really can't get my head pressure below 110psig without my DX units and defrosts going bonkers. There are ways around that, of course, but at this point they are much more trouble than they are worth.

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Originally Posted by US Iceman

OK, what happens if you raise the suction pressure 1 inch of vacuum? What happens if you raise it another inch?

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12" is the setpoint we arrived at after extensive testing. When I got here they had it at 16" - we slowly raised pressure until our residence time in the hardening freezer was inadequate.

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Originally Posted by US Iceman

What would you say if I mentioned some facilities have achieved reductions of up to 50% over an annual period?

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I would say the same thing that I do when I read about six sigma/lean projects that tool change times from 24 hours to 3 hours: "Gawd, they really sucked at what they did initially didn't they?"

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Originally Posted by US Iceman

OK, how much oil was put into this same system during the same time?

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Just about the same amount.

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Originally Posted by US Iceman

Trying to justify changing the oil on energy reduction would be a giant leap into fantasy if I were asked.

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A 3% reduction in energy costs gives me a <6 month payback to move to synthetic oil. Since my bean-counter overlords require a 2 year payback, my target is 0.75% - I have yet to see a study that didn't show that much of an improvement with synthetic oils.

Since my current oil is effectively a viscosity of 90, I would expect to see a significant energy usage reduction just from the viscosity alone.

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Originally Posted by brian_chapin

Our setpoints have been picked through multiple trials - we started at what we were told was normal and then worked to maximize efficiency.



We actually have a fairly large fluctuation in load. We have three large -20 storage freezers, a hardening freezer, three ice cream freezers, two bulk ice making machines, and a pair of plate&frame water chillers. I can usually tell you what production equipment is running by the sound level in the engine room.

The floating head simply moves my condensing pressure based on wet-bulb. Being in the northeast we get some bizarre temp/humidity fluctuations and since I don't feel like having someone at the control computer all day it makes life easier to have that automatically controlled.

Sadly, due to system design I really can't get my head pressure below 110psig without my DX units and defrosts going bonkers. There are ways around that, of course, but at this point they are much more trouble than they are worth.

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Set points should be optimum and flexible. I mean that optimum set points should be changed based on refrigeration load and ambient condition. Suction pressure can different for summer and winter. Fequency of defrosting should be changed based on rate of frost formation. Wet bulb approach should optimum and should be changed from time to time. Early you mentioned that your all 6 compressors run nearly constantly and I assumed that your load is constant.
Defrosting can be done at head pressure lower than 100psig, but this requires precise adjustment. DX coils usually installed for dock cooling. At 110psig of head pressure ambient temperature will be lower than 15degC and refrigeration load for the dock is lower than 50% of design load. Probably, at this head pressure liquid supply to the coils will be able to provide 50% capacity of these coils. Where is going suction from these coils(directly to high stage compressors or to intermediate receiver)?

We are getting off topic a little describing energy efficiency of the system versus energy increases due to oil viscosity.

A new thread should really be started to continue the system improvements discussion or effects.

My suggestion on the oil issue is call one of the manufacturers and ask them this: How much energy can I expect to save using your compressor if I use brand X oil?

Tell them it's a heads-up comparison; for the same operating conditions on the same compressor, what will they estimate the energy savings to be?

No changes in suction or discharge pressure, only a change of oil...

Be careful changing oils, some are not compatible and the drop or two leftout in the system can turn into wax when new oil mixes with it. Then it will plug solenoids, strainers and cause headaches.

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Originally Posted by keepitcool

Brain,
PLEASE do not use the royal purple! I had a boss in a past life that sold this to one of my very good and large customers. I was not happy about this and soon found major issues. The worst was on a Frick RXF101. It was in a hydrogen plant. We had three failures in 9 months. Frick would not honor the warranty due to the royal purple. We also added it to the refrigeration machines. This stuff is probably great for cars or whatever but not refrigeration compressors. After the first failure we did not blame this stuff but after the second we did and removed it. The damage is already done at this point. Imagine how hard it is to get this garbage out of the package. The third failure happened after the oil change. After all of this I will say the package was replaced but not by us. They have never worked in that large group of facilities again. This incident prompted Frick to do studies on it and it was then added to the "band products list".

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Dear keepitcool,

I am a new member of the forum and I live and work in Italy with synthetic lubricant and I was wanting to know more about the problems you had with Royal Purple in the Frick compressors. i will be upfront with you we deal with this line of lubricants and other synthetic products as well. You mentioned that you had 3 failures but did not say if they were lubricant related or not. I ask you more details because we also have clients experiencing probelms with various types of synthetic oil and would like to understand more.

Thank Lonestar

All three failures were deemed to be lubrication related. I am not saying that this is a bad product or that synthetics should not be used. We have had success with synthetics and i actually prefer them in a lot of cases. I am sure that Royal Purple is fine for a lot of uses but if you use it in refrigeration compressors cross your fingers!!!

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Originally Posted by keepitcool

All three failures were deemed to be lubrication related. I am not saying that this is a bad product or that synthetics should not be used. We have had success with synthetics and i actually prefer them in a lot of cases. I am sure that Royal Purple is fine for a lot of uses but if you use it in refrigeration compressors cross your fingers!!!

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Dear Keepitcool,

being in the lubricant business for over 15 years we have to keep our fingers crossed many times since we never really know the history of an industrial machine. Many times we can not switch forma mineral oilot o a synthetic because of the natural solvency of synthetic compared to mineral oils. I do not understand why royal Purpel oil has had different results for you since it is a PAO /alkybenzene based oil which is very similar to many other top synthetic refrigeration oils on the market. The only difference is the additive package that RP uses for film strength. I would like to know your results since here in Italy we are lubricating, with very good results many NH3 compressors for over 4 years ( Mycon and Kobelco screws). I know every situation is different but how did you come to the conclusion that the failures were lubricant related??? Also, I would like your advice on the use of a 2 staged double hydrocracked base oil for ammonia applications. We also import this type of oil from a major producer of refrigeration compressor oil in the USA.

I ask you these questions because after reading your replys you seem very knowledgable ont his topic.

Saluti from Italy LONESTAR

Hi,

Check out CPI oil site on the web. Good synthetic oils, lists pros cons and compares to mineral oils. We use CPI 100-68 on our NH3 plants. Brilliant stuff.
Grant