Rotary Screw Compressor iso-46

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Hey We are running a Rotary screw compressor in our plant, actually two. When it was first bought the company sold us on Synthetic oil and oil sampling. They'd come out take a sample and send us a report. Never explained what was on the report in detail. When the report said change filter or oil change recommended we'd change. After doing it this way for years. One day a report came back saying something to the effect that "too much free water sample couldn't be tested", we had another sample taken and before the report came back we lost the air end. When we complained to the company selling the service they wanted our maintenance records which we gave them. They then said it wasn't their fault because the oil was only good for 8000 hrs or one year max. We'd gone considerable longer. Live and learn. We switched to their dyno oil and switched it out every 6 months. Then I became boss and decided to go back to the synthetic and do annual changes. The synthetic was relabeled Royal Purple as per MSDS sheet.

Fast forward 10 years and along comes a salesmen from Lubrication Engineers. He sells me his ISO-46 Product #9046. I run it and the next time around he suggest adding oil sampling. Well we pulled the first sample at 7 months and the Phosphorous went from 508ppm to 11ppm. The sales guy stopped out and said time to change he isn't sure why its dropped so much. Acid Number went to 0.86 and Viscosity (40°C) went from 48.6 to 54.0.

OK so we change it in under 1 year I'm not happy but hey we caught it before there was trouble.

I sent off a virgin sample and then another at 2 months 1100 hours run. Virgin came back with 674 Phosphorous!! The two month came back it was down to 25ppm, Acid number is 1.84 Vis.cSt 53.7. Comments are generic stating it doesn't mean that the oil is out of ISO specs, just that it isn't where it should be for this particular oil.

I have an email in to the sales guy to see what he has to say. For his prices I may as well buy Amsoil which is said to be an 8000 hour oil and even if I changed it at 4000 hours its half the price.

Can anyone chime in as to what might be going on here?

Thanks in advance,
 
How the heck does a phosphorous level drop? My understanding is that although ZDDP does indeed get "used up" since its a sacrificial anti-wear additive, the Zn and P elemental readings should still be the same because they're still present in the oil, just not as ZDDP any longer.

Unless the P is reacting with some metal in the compressor itself, or reacting in a way that precipitates it out of solution, where is it going?
 
A compressor oil will not have zinc. Just phosphorous for mild EP. But 500 ppm or more is more than I've ever seen. I'd be wondering about the lab.
 
Hey guys I have sweetened my oil by taking out 10 gallons form the 30 gallon sump and ran it while sending samples off.
One thing that is puzzling is the fact that the Zinc level is rising as the Phosphorus has stayed low. LE doesn't know where the Zinc might be coming from. Widman says there shouldn't be any zinc in compressor oil?
This oils been changed out several times now and I would say its been "flushed" so I'm not certain what happened. We just did another PM and went to Amsoil, I'm still waiting to hear back from LE on my last samples I sent them.
 
Zinc is typically an additive or outside contaminant. It can come from a lot of different sources. Gotta check your air intakes. The TAN and viscosity is pointing towards varnish and/or outside contamination. You'd need to post the UOA results...

It sounds like you've got a heavily varnished compressor. Chapala Filter Co. is pretty close to your location. They have a compressor cleaner concentrate that you can put into the current oil at 10-20% concentration. Run the compressor for a week, watching your filter pressures to make sure they don't get clogged. It's a strong cleaner that will break down all the varnish in the compressor.

Then get some of their "advanced formulation" fluid and put that in there and you should be good.

Varnish comes from cheap oil or oil being run for too long or too high of temps. Before you switch to a better oil, you gotta clean that machine really well first.
 
OK Zinc is now through the roof 225ppm. wear metals pretty low 1ppm Iron,Aluminum, first time they have shown up on a report. Phosphorous is still very low 24ppm. Acid is high 1.11KOH/g

We had been running Kaesar S460 since new and rebuild. From the MSDS its made by Royal Purple. I have been running the LE now for about 2 years and have changed it out several times. I'm wondering if the good LE oil is actually cleaning away the varnish as you describe, camelCase.
I'm looking at getting a filter machine to run the oil through when the plant goes down for maintenance on Monday mornings but the price of one has been a hard sell to the guys up front. Making one is an option I guess I could spread the cost or several purchases and they would notice.

I don;t know where I'd be getting Zinc as an outside contaminant since all the other reports show it 17,5,12, and 97 ppm this 225 seems alarming as well as the acid number.

I will look in to the cleaner additive mentioned.
 
Zinc can be an indicator of wearing brass components.

Could be components that have already worn, and the particulate was simply "captured" by the varnish.

What's the discharge temp?
How long was the oil that was sampled run in the compressor?
What type of oil is it?
What kind of environment are you in?
Where's the intake of the compressor?
What's manufactured where the compressor is?


Sounds like you got a fun one on your hands!
 
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