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Author: Subject: Pump oil for Rotary Vane - What grade?
Tdep
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[*] posted on 14-1-2019 at 04:25
Pump oil for Rotary Vane - What grade?


I've had this absolute workhorse of a belt driven rotary vane vacuum pump for several years, I believe it dates back to the 50s. It is basically the same one as here: http://www.gandmtools.co.uk/shop/edwards-speedivac-vacuum-pu...
Its here in video form when I first got it: https://youtu.be/lUUEE08QIV4?t=36
It is... a lot less shiny now unfortunately.

Anyway, i'm ashamed to say it has gone three years of heavy use without an oil change. It needs one, but I'm not sure what to get? Here on eBay, there's oil that looks appropriate https://www.ebay.com.au/itm/Vacuum-Pump-Oils-Genuine-Quality... but there's a few different grades, mostly the ISO number changes.

Is there anyway to know what ISO grade my pump would take, or does it not even matter? I don't know what is in there currently, it came pre-filled when it bought it from a stranger down the road (bless Gumtree).

I just use it for general lab vac stuff, no high vac stuff although I believe it would make a great roughing pump. Thanks.
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OldNubbins
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[*] posted on 14-1-2019 at 04:44



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Dr.Bob
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[*] posted on 14-1-2019 at 07:45


Welch and Fisher sell general purpose rotary vac pump oil, but you can also find it at some auto part stores, HVAC supply stores, and many other places. Or try google, it is not hard to find. Rotary pumps are not that choosy, so not that much variation. But you don't really want to use engine oil, as that contains some crap that you don't want in a vacuum pump.
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wg48
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[*] posted on 14-1-2019 at 15:24


If the pump is old, worn and your lab is heated select a higher viscosity than recommended by the manufactures to get a better vacuum.



Borosilicate glass:
Good temperature resistance and good thermal shock resistance but finite.
For normal, standard service typically 200-230°C, for short-term (minutes) service max 400°C
Maximum thermal shock resistance is 160°C
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XeonTheMGPony
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[*] posted on 14-1-2019 at 16:11


Hydrualic oil for pump jacks has been reported to work well in older worren pumps.
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Tdep
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[*] posted on 14-1-2019 at 20:35


Good to hear they aren't that choosy. I'm not sure I really want to increase the vac strength that much more... for general lab use I'd start to worry about imploding my cheap chinese glassware and that would be an annoying to consider.

Anyway, being in Aus there isn't as much around as I assume is in the US, and buying things online that are this heavy is a no go. So, I'm pleased to find this: http://www.gulfwestern.com.au/product/ultra-clear-compressor...

The ISO 46 grade, while it is probably no-where near as good as the Ultragrade 19, at least I'll have enough that I could change it on a fairly regular basis. Looks like it is $150 for 20L, which is okay.

Actually.... it does seem to have a lot of additives that Dr Bob was mentioning... that's a shame.

To quote the MSDS:

• Formulated with state of the art additive packages incorporating the
latest technology for extreme service requirements
• Synthetic base stock gives better thermal and oxidation resistance
allowing longer drain intervals and cleaner components. Up to 5000
hours of service life (Consult manufacturer)
• Provides state of the art anti wear additives for longer component life


...Thermal decomposition and combustion produce noxious fumes containing oxides of carbon,
calcium, phosphorus, sulfur and zinc. Hydrogen sulfide and alkyl mercaptans and sulfides may
also be released.




Maybe i'll just get the ISO 46 from the eBay link in my first post
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j_sum1
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[*] posted on 14-1-2019 at 20:57


Hmm

A couple if years back I picked up 4L of something suitable from Repco for around 60 bucks.
I forget the brand and details except that it was the only thing they had in stock that was specifically designed for vacuum pumps.

You might try somewhere like TotalTools or something similar that sells compressors and air tools.

20L seems like an awful lot and it would be good to have less outlay than $150.


[edit] fixed typos

[Edited on 15-1-2019 by j_sum1]
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XeonTheMGPony
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[*] posted on 15-1-2019 at 03:35


Just get 30 weight compressor oil, it is usually pure oil with no additives.

if not aiming for 2 micron nominal vac that aut to be fine, I've used cheaper oils to flush and clean my pumps in the past to no ill effect.
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Sulaiman
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[*] posted on 15-1-2019 at 08:38


I've only done one oil change for my Chinese HVAC dual-stage rotary vacuum pump, so not reliable advice but,

flushing old oil with cheap vacuum oil seems a good idea.

I have not needed maximum vacuum / very low pressures so far because the liquids/solvents that I use would need cryogenic condensers,
so 'thin' oil is best as it puts less load on the motor,
as your pump is old and worn then 'thick' oil may give a better vacuum.




CAUTION : Hobby Chemist, not Professional or even Amateur
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beerwiz
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[*] posted on 24-1-2019 at 17:37


The best oil to use for rotary vane vacuum pumps is pure Mineral Oil like the one you can buy from the pharmacy. I tried all types of oils, and the best and deepest vacuum was with mineral oil not to mention that it also produced the least amount of mist coming out of the exhaust. It's the perfect oil, trust me.
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