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Vacuum pump oil changes. Pages: 12

70monte on Fri August 12, 2011 5:04 PM User is offline

Country of Origin: United States

I have a Robinair #15600 6cfm vacuum pump that I bought new about five years ago. I have changed the oil in it after every use but was wondering what everyone else does on vacuum pump oil changes. The owner's manual suggests to change it after every use but I was wondering if that is really needed. Most of the time, the oil in the site glass still looks new after I use the machine. I just bought another gallon jug of Robinair pump oil and the stuff was not cheap. I usually only use the pump maybe twice a year. Sometimes I feel like I'm wasting good oil.

So what do you guys do or suggest. Thanks.

Wayne

Airstream on Fri August 12, 2011 5:44 PM User is offlineView users profile

My Mastercool pump recommended no later than six month intervals if I recall correctly.

We use much bigger oil pumps where I work, and we typically don't change the oil until the pump won't pull a decent vacuum because there's too much water in the oil. That's not right, but it is the way it is.

My current plan is to always make sure my pump gets hot enough to boil off any water before putting it away. After that, a new bottle of oil will be on standby for the next time the pump is used. If the pump does not pull down to my liking, the oil will be changed.

Tom

70monte on Fri August 12, 2011 6:06 PM User is offline

Wow, every six months. Mine says after every use but I'm thinking that is too much. There have been a few times that the oil was a little murky after use and I could see changing it then, but most of the time, the oil looks just like I put it in. I may go every other time depending on what other feedback I get here. Thanks.

Wayne

Dougflas on Fri August 12, 2011 8:34 PM User is offline

every time is best.If you used a micron guage, you'd see the difference.

70monte on Fri August 12, 2011 8:43 PM User is offline

I don't have a micron gauge so maybe I will stick with changes after every use. The vacuum pump oil I just bought was almost $25 for a gallon jug. This seemed a lot higher than the last gallon jug I bought. I guess it's cheap insurance though. Thanks.

Wayne

pinch on Sat August 13, 2011 12:25 AM User is offlineView users profile

Mine states every 100 hours of use.

GulfstreamV on Sat August 13, 2011 9:30 AM User is offline

I agree w/Dougflas. A factory Res/Com HVAC field support tech. that lives in my neighborhood schooled me on pulling a vacuum during my project. Change the oil each session, and dispose of the used oil after the session is done. Flush w/clean oil if necessary. Oil is considered a disposable commodity. A micron gauge is a must to verify this. I'm a believer after his help and seeing the results. HTH.

70monte on Sat August 13, 2011 10:12 AM User is offline

Thanks for the info. I will continue to change after every use.

Wayne

chris142 on Sat August 13, 2011 12:12 PM User is offline

Our Robinair junk prompts me to change it's oil every 10 hrs.

70monte on Sat August 13, 2011 4:34 PM User is offline

What problems have you had with the Robinair vacuum pumps?

Wayne

Airstream on Sat August 13, 2011 5:00 PM User is offlineView users profile

Quote
Originally posted by: Airstream
My Mastercool pump recommended no later than six month intervals if I recall correctly...
Okay, I did not recall correctly.

Since this thread is getting traffic, and I'm curious what everyone else is doing, here are words from my Mastercool's manual:

a) After every evacuation, while the pump is warm and oil is thin, take a small sample of oil from the drain port.
b) If the oil is contaminated, drain the oil by ...[appropriate means]
c) If the pump has been sitting for more than one month, the oil is considered contaminated regardless of appearance.
d) [instructions for changing oil in my pump]

Tom

70monte on Sat August 13, 2011 5:34 PM User is offline

So does that mean if your pump has been sitting for more than one month with clean new oil in it, that it is considered contaminated.?

My pump sits for many months and sometimes over a year before it's used. It sat for about a year this last time between uses. Interesting information. Thanks.

Wayne

Airstream on Sat August 13, 2011 6:10 PM User is offlineView users profile

Quote
Originally posted by: 70monte
So does that mean if your pump has been sitting for more than one month with clean new oil in it, that it is considered contaminated.?
Yes.

New oil is contained in a conveyance which is free from air. Oxygen is in air. Oxygen is an oxidizer - it allows everything else to rust stuff.

So anytime air is in contact with the oil, bad things are happening. So it would appear best to drain the oil out between uses. But that's the way your pump was most likely delivered to you (didn't it say "tested at factory"?) So the factory started the oxidation process by leaving trace amounts of oil in the system.

I don't think you can win here, Wayne. But I recommend to you to leave the pump dry between uses - that's the way you probably got yours, and the instructions most likely said nothing more than "fill with oil before using".

Tom

Edited: Sat August 13, 2011 at 7:42 PM by Airstream

GulfstreamV on Sat August 13, 2011 11:01 PM User is offline

Quote
Originally posted by: Airstream
Quote

"I don't think you can win here, Wayne. But I recommend to you to leave the pump dry between uses - that's the way you probably got yours, and the instructions most likely said nothing more than "fill with oil before using".
__________________________________________________________________________________________________________________________________________



Airstream:
That's the recommendation that I got from the factory tech. I guess my post was poorly written. To try again, the Tech. advised draining the pump completely at the end of the job. Should you see any visible signs of contamination, flush your pump w/clean oil per the manufacturers instructions. He basically took the cap off the oil reservoir and poured fresh oil through the pump body until clear. Store the pump dry of oil. The cost of the oil is just part of doing the job correctly.
If it wasn't for the advice received on this forum, from ACKIts, and from fellow friends, my A/C project would have been a disaster. HTH.

Edited: Sat August 13, 2011 at 11:08 PM by GulfstreamV

70monte on Sun August 14, 2011 1:50 PM User is offline

Thanks guys, I didn't even think of that option. That probably would be the best thing to do. I have never done that so I probably have done some damage to the pump even though the oil still does look new when I go to use it.

Wayne

chris142 on Thu September 01, 2011 10:32 PM User is offline

Quote
Originally posted by: 70monte
What problems have you had with the Robinair vacuum pumps?



WayneNothing but problems with our 2 Robinair AC machines. That and Robinairs complete lack of customer service. I/We will never buy another Robinair AC machine and I/We will not recomend them to anyone looking to buy an AC machine.

Robinair basically avoided doing any warranty work while the units were still under warranty. Once out of warranty Robinair was ready to take our money to repair the machines.

Bob on Fri September 02, 2011 8:25 AM User is offlineView users profile

If you are not going to use the vacuum pump for a while, I would suggest storing it with oil in it. This would prevent surface rust. When you are about to use it, change the oil. Just my opinion.

70monte on Mon September 26, 2011 6:50 PM User is offline

That is a good idea also. I have always kept oil in it up to this point and have not had any problems. I guess there is a good argument for both ways.

Wayne

Dougflas on Tue September 27, 2011 12:46 PM User is offline

Here isa he best of both worlds. When you are done with a job, leave the oil in the pump. When you use it again, pull a vacuum with the previous used oil for a few minutes to heat the pump and oil up. then change the oil. Repeat this for the next usage. I have been using this method for automotive and HVAC. i don't have vacuum problems and I use a micron gauge to verify.

70monte on Tue November 08, 2011 8:39 PM User is offline

Dougflas,
That does sound like a good compromise and is what I will do since I have not changed out the fluid yet.

Wayne

UK Tech on Wed November 09, 2011 1:06 PM User is offline

When I had a business repairing and servicing Robinair rec/recharge machines, they would throw a message every 10 hours of vac time. I had 600 customers, and would visit most machines every year. Nearly all would be showing the message. I would bet a years salary that no-one would change the oil in between the annual service. In the beginning I would leave the fresh oil left over from the change with the customer, so he could use it for the next change. It would never get used. In fact, some of the stupid dealerships actually used it for refrigeration oil, as they didn't know the difference. As a result, I stopped leaving it behind. I would see from their invoice history that they never purchased vac oil in between the annual services.

Many pumps would be runnning virtually dry, as they would often try vacuuming a system with a huge hole in it, and all the oil would vent as mist through the pump exhaust. But part of the service was to accurately measure the vacuum level achieved, and in the 6 years I had the business I only ever replaced 4 or 5 pumps. And 1 or 2 of those was an electrical fault.

So despite the pumps getting an absolute hammering by operatives that didn't give a stuff, used many times a day, and with no oil changes or top-ups, those pumps were seeing many hundreds of hours between oil changes without failure, and with very little degredation of performance. Certainly not enough to stop the vacuum level getting below the threshold necessay to boil off the moisture.

Frosty Snowman on Mon January 23, 2012 7:00 PM User is offline

Quote
Originally posted by: Dougflas
Here isa he best of both worlds. When you are done with a job, leave the oil in the pump. When you use it again, pull a vacuum with the previous used oil for a few minutes to heat the pump and oil up. then change the oil. Repeat this for the next usage.

Sounds like a great plan, minimizes operating cost while protecting the pump.

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