soma
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vacuum grease
Wondering if anyone has tried using Lowe's or Home Depot's vacuum grease? ( http://www.homedepot.com/p/Super-Lube-3-oz-Tube-Silicone-Hi-... ). It's much cheaper and easier to get than the Dow Corning high vacuum grease.
Also, anyone know if there's a cheaper oil that can be substituted for the Welsh Duo-Seal vacuum oil?
Thanks.
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AvBaeyer
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I have been using Mobil Vacuum Pump oil which works just fine. I got it at a good price from Zoro Tools. I have a single stage pump that easily pulls
0.4-0.5 mm using the stuff.
As for the vacuum grease you refer to, I would be worried about how easily it is removed from the site of application. The Dow-Corning grease is
easily removed with a bit of methylene chloride on a towel. I bought 1 oz of the Dow-Corning grease a long time ago. You use it so sparingly that it
lasts a long time and so is worth the price. My opinion.
AvB
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Dr.Bob
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For normal vacuum experiments I expect any good vacuum grease would do. If you were running a MS vacuum pump or a trace analysis lab, then being the
best there is is great, but it is hard to find a small amount of the good Dow corning stuff. I have used it, as well as several other brands, and
they are all similar in dissolving in DCM (or hexanes in some cases).
I would agree that Mobile's vacuum pump oil is likely fine, if you cannot find that, you may be able to find a simple oil that is not designed for car
engines that will work. Car engine oil contains all sorts of additives designed to protect internal combustion engines which might not be ideal for
pumps. But even most car oils would likely work for simple work. You do need an oil with no low MW or low BP components, as they will keep the
vacuum from getting very low. You might even be able to google asking "what is the closest type of oil that works in a vacuum pump". I found these
threads with useful info below, but there were many others. The answer is that vacuum pumps work best with the proper vacuum pump oil, which you can
buy at Autozone or other auto parts stores, but in a pinch, others can work but are not ideal.
http://cr4.globalspec.com/thread/2023
http://www.autozone.com/test-scan-and-specialty-tools/a-c-va...
http://www.hyvac.com/tech_support/Oil%20Suckback%20Problem.h...
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NedsHead
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I've been running pneumatic tool oil through my vacuum pump, it was all I could find in my local area for a while and the pumps been working fine, and
I use dielectric grease on my joints. I might give ptfe tape a try next, it's cheap and would be easy to remove after
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soma
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Thanks for the replies.
I've been using the dow corning grease and duo-seal oil. We've got a welch 1400 ? pump. I've been getting 2mm on the manometer when it's well sealed.
How do you measure 0.5mm? We've got a thermocouple gauge that I've never used as it was finicky.
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AvBaeyer
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"How do you measure 0.5mm? "
I have a digital vacuum gauge. It's a TIPI brand which cost about $100. It appears to be quite accurate based on the distillations I have done and
comparing boiling points to literature values.
AvB
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