Question about oil change on vacuum pump

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I monitor the performance of the pump. WHen it starts taking longer to draw a full vacuum its time to change the oil. I dont believe that everytime you use it is neccesary just someones elses way of doing it that makes them happy. Usually its moisture build up in the oil that starts to slow the actual time it take for a pump to draw full vacumme.
 
Is there something about the vapors from the stabilizing liquids that contaminate the oil ?

I used vacuum pumps for four or more years when I was working in a Physics research lab without changing the oil. The gases being pumped had no vapors from liquids.

I think you should get an expert opinion from the pump manufacturer and from the manufacturer of your stabilization equipment.
 
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Terry is spot on above. If using Cactus Juice, there is nothing that boils off the resin at normal room temperatures and full vac but there is still likely moisture in the wood even if it was dried properly. This moisture IS boiled out of the wood under full vac at room temp and condenses in the oil, thus contaminating the oil. Contaminated oil will cause your pump to pull less vacuum since the oil is what helps make the vacuum.

The owner's manual of every rotary vane oil filled pump I have ever seen says to change the oil after every use. Remember, the manuals and these kinds of pumps are targeted to the HVAC technician. They use this type of pump to extract the water out of refrigerant lines prior to charging them with freon. The water that is boiled out ends up in the oil, thus the recommendation to change the oil after every use.

I usually tells folks to change the oil after every 6-8 runs or sooner if you are not properly drying your wood ahead of time or if the oil starts to look really bad in the sight glass.
 
Neil said:
Hi I was wondering what the recommended time for changing the oil in my vacuum pumps. I had someone say every time you use it change the oil, I hope this is not true. That would be costly. Thanks Neil:tongue:
Click to expand...

Hi Neil,

I can furthermore say, from what Curtis mentioned that, moisture in the wood, is the major cause of water appearing in the oil. The other thing that everyone needs to consider is the ambient moisture content, in the area where you are using the pump, moist air can enter the chamber while you are preparing the blanks for stabilization, and that will be sucked into the pump and therefore endup in the pump oil sump.

My air ambient contains always some humidity and in rainy days, that humidity % double or triples so, stabilizing done in those days, will put some water into the oil.

I suggest that you do a test that, will show you very easily if your oil has any water or not. After you used the pump, let the oil cool down a bit and then grab a clean/dry plastica empty water bottle/glass jar and pour the oil contents into it, the pump has a bleeding screw below the oil level clear plastic window so, remove that screw and empty the oil into it.

While sometimes is immediately visible that is water in that oil, you should put the bottle aside overnight, with a lid or without, the next day, you will clearly see if the oil has water or not as the water will be at the bottom of the bottle, like this 016 (2).JPG

I have found that, if I drain the water before I use the pump, and top up with new oil to bring the oil level to the middle of the low and high (try not to overfill), I get the best possible use of the oil and reduce any damage to the pump from too much water mixed in the oil that results in poor vacuum.

I have in fact made a post (once again, I should have made a dedicated thread and not put this info in the middle of someone else's thread, that is always a nightmare to find...!) about this very issue where I show the simple modification I made to the bleeding screw to allow easy removal of the water, before each time the pump is used and not endup with the screw coming off and the oils come out also before you can stop it or find the screw and manage to get it in, something that becomes a nightmare when your finger are full of oil so, have a look here on last post #43.

In fact, the whole thread is worth reading, lots of other very important information about the vacuum pumps most of us use...!

Cheers
George
 
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Wow.. that was only an hour adventure reading all the different threads about the oil. :) Thanks for the ideas though. I have a pump and chamber but have not really done much with it because the weather has not cooperated lately. I bought some Cactus Juice and will do it soon, but now I see I need to do some modifications to the pump first. Not sure I can afford it though. I paid $10 for the pump as it did not work. It looked brand new and brought it home and discovered the switch was bad. One day I might replace the switch, but in the meantime wiring around the switch works. :)

Thank you George and Curtis and all who contributed to this and the other threads!
 
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