FAQ - Drained your old pump oil? Save it! Use it for new acquisitions!

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Richard Hull
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FAQ - Drained your old pump oil? Save it! Use it for new acquisitions!

Post by Richard Hull »

Most of us will only ever need or buy a single mechanical pump. However, good deals may come along such as free or too cheap to pass up. You may get a great deal on a larger pump with increased pumping ability. Assuming you change your oil in your main pump from time to time, You see it as discolored and maybe containing some minor debris. Save it! Place it in a clear or translucent container. Set it aside. Over time you will see debris settle out to the bottom. Save only old oil drained from vacuum pumps used on your fusor only! Never save drained oil from a new acquisition, no matter how good it looks. You have no history on that oil.

Should you buy an unknown pump with no oil in it or a pump with really nasty oil in it. Drain the filthy old oil first. Decant, carefully, your old saved oil into the new pump of unknown capability being careful not to let the bottom debris into the new unknown pump. If the new pump was dry, let the "new" old oil sit in it for a while to seep into the vanes and seals for maybe a day or so. If a belt drive, try and turn the pulley by hand to see if the pump is locked or seized up. If it failed to move by brute strength, tap gently with a hammer on the spokes of the wheel in the correct direction of rotation. (note: most all belt drive pumps have an arrow cast into their case bodies indicating the correct direction of rotation.) It should free up at some point and move just a bit. Stop hammering and try brute strength again. It should now turn fairly freely. Give it a few manual rotations to make sure there are no rough spots.

You can now turn on the pump blanked off with your TC gauge and see what it will do. You can be sure that the old oil is still very good and far better than wasting brand new oil for a first run test. Again, run for a full hour then drain and see what comes out. If during the run the gauge never went below 100 microns, and the oil comes out fairly clean, you might have a bad pump. (frozen or locked up vanes, scored walls, etc.)

Old oil that has had months to settle out is still very good oil for testing and cleaning unknown acquisitions. I have a couple of gallons of old drained pump oil hanging around here.

If you run your main pump often, say, every other day, replace your oil every 6 months for sure. If you totally seal off your exhaust via a valve, like I do, so the oil can't breathe, (pick up moisture from the air), I have found clean oil is still in my pump run 20-30 times in a year when I normally drain it after 3 years!! I just have to remember to open the exhaust valve to the outside air before turning my pump on.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
ChristofferBraestrup
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Re: FAQ - Drained your old pump oil? Save it! Use it for new acquisitions!

Post by ChristofferBraestrup »

I would like to add, that chemists takes horrendously care of oil filled rotary vane pumps, but use them in a muriad of applications such as freeze drying, destillations and the like. This means the oil on rotary vane pumps that are surplus from wet labs, and likely other process operations as well can be heavily contaminated with whatever solvent or volatile chemical that has been worked with in the lab for the past 5-25 years!

It should go without saying that oil like this is orders of magnitude more harmful than fresh oil. There is also no easy way of testing this, except of smells - but most people would toss very smelly oil. I guess it's a judgement call depending on where your pumps has been previously in life.

Anything that has been sitting as a foreline pump for a hi vac system like a mass spectrometer is probably clean enough not to worry about, though.
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Richard Hull
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Re: FAQ - Drained your old pump oil? Save it! Use it for new acquisitions!

Post by Richard Hull »

Good point. In the surplus world you don't know where your surplus pump acquisition has been. Naturally, saving old oil from a fusor system is fine for testing a recent purchase as you know where that old oil came from. Many used or surplus pumps have had a terrible life. That is why there is a lot involved in getting such a purchase ready for testing. Draining a bit of the old oil for a visual inspection and deciding to just dump it or use it as is for a test run is important. Checking for a seized pump, etc. As direct drives are common now, testing for seizure can't be done easily.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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