Vacuum Pump Oil

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I just purchased a 2-stage vacuum pump from Harbor Freight and have a question about oil for these units. Included in the box is a white (no label) bottle of what looks like clear mineral oil. I went ahead and used it, but I will probably want to change it out after the first couple uses, to get out any metal that might accumulate during break-in. I can't say that I've ever seen oil on a store shelf that is specifically for vacuum pumps (though admittedly I've never looked for it) and I don't recall ever seeing clear lubricating oil used for any kind of appliance / industrial application. Is vacuum pump oil unique, or different from compressor oil for example? What about the oil makes it specifically for vacuum pumps?

Anyone know where I can find the right oil, and which type/brand do you think is best?
 
If it is built like most compressors and pumps, a regular ND 30 weight (like that sold for air compressors) would be fine. You can still get it in KY (not in CA)

Otherwise, any good ATF will work fine if it's about the same viscosity.... but I'd definitely lean towards the 30 grade oil
 
Serviced a lot of oil sealed vacuum pumps in a previous career. Vacuum pump oil is pretty much just mineral oil (unless you're doing oxygen service, but that's a different problem).

But, don't use anything other than vacuum pump oil if you want to actually pull a vacuum. Vacuum pump oil is specified to have very low outgassing so the partial pressure form the oil itself is low. You'll get back streaming of the oil no matter what, but that can be prevented by installing a trap between the pump and the thing you're pumping down.

VWR and the other scientific supplies will have vacuum pump oil, as does Amazon.

BSW
 
This stuff

Screenshot_20190623-143208.png
 
As indicated above, the single most important property of a vacuum pump oil is not so much its lubricating ability, but rather its vapor pressure.

Essentially, in a rotary vane pump, even though the oil DOES lubricate the mechanics, its more significant function is to both seal the vanes against the housing AND also actually physically transplant the pumped gases out of the pump. You can observe the latter directly when you first power on a pump and it's either pulling down the vacuum system from atmospheric pressure, or if there's a massive leak-the pump will make a "gurgling" sound, usually accompanied by either mists of oil or sometimes larger droplets "burping" out the exhaust. The theoretical minimum vacuum a pump can achieve is limited by the vapor pressure of the oil. Sometimes in research labs, pumps get used(abused) to pull off solvents without adequate vapor traps, and also don't get oil changes as often as possible-that leads to the oil loading up with solvent and increasing the vapor pressure. I recall working in one lab where an old Sargent-Welch belt-driven pump was used several hours a day as part of a set-up that removed carbon disulfide(too lazy to look it up, but I think it boils at around 45ºC) and no one could remember when the oil had last been changed. With a gauge directly hooked up to the inlet, I measured ~100 torr, which is miserable for this style pump. The oil I drained out was a lot less viscous than what I'd expect pump oil to be(plus it smelled like CS2), combined with a lot of sludge that came out at the end. We had a 55 gallon drum of "#19 pump oil"(generic branded Inland 19) out back, so I filled a bottle and ended up changing the oil 3 times that day. The end result was a pump that was not only quieter, but would reliably pull 10^-2 torr. Unfortunately, I was only there for 3 months about 10 years ago, and it wouldn't surprise me if the oil hasn't been changed since...(although the pump might have died without that).

In any case, in all that rambling, unless I have a good reason to use otherwise, Inland #19 is my go-to, and it wouldn't surprise me if the linked NAPA oil is a generic of that. It's basically just a heavy hydrocarbon oil.

https://www.capvac.com/inland-19/

Inland 45 is my preferred oil for things like mass spec use, although it's ~4x the cost of #19 and for HVAC work I seriously doubt you'd see the advantage of it. I've used Inland 19 for mass spec applications in a pinch, and it's been perfectly serviceable(in fact I have one running it now-changing it is on my to-do list for the week). The only real failing is I see a somewhat higher hydrocarbon background than Inland 45, but then I can actually directly measure that(and identify that as the issue)-I doubt you'd see it with an HVAC system.
 
Stick with only vacuum pump oil in your pump. Keep it changed often.

Yellow Jacket and JB Industries both make a good quality vacuum pump oil for hvac use. Both can be found online.
 
Originally Posted by CDX825
Stick with only vacuum pump oil in your pump. Keep it changed often.

Yellow Jacket and JB Industries both make a good quality vacuum pump oil for hvac use. Both can be found online.


The JB Industries Black Gold vacuum pump oil seems to work well in my 6cfm vacuum pump. Not so easy to find up here unfortunately.
 
The proper oil in a vacuum pump acts as a blotter and absorbs all of the moisture and non-condensables. As the oil becomes saturated with these contaminants, the efficiency of the pump is dramatically reduced. Maintaining clean oil in the pump ensures that the pump will operate at peak efficiency and prolong its life If the oil turns white during operation it has water in it or if your only going to use it couple times a season change it everytime.. Keep a 1/4" flare cap on it when not in use.
 
Originally Posted by Fitter30
The proper oil in a vacuum pump acts as a blotter and absorbs all of the moisture and non-condensables. As the oil becomes saturated with these contaminants, the efficiency of the pump is dramatically reduced. Maintaining clean oil in the pump ensures that the pump will operate at peak efficiency and prolong its life If the oil turns white during operation it has water in it or if your only going to use it couple times a season change it everytime.. Keep a 1/4" flare cap on it when not in use.

Interesting cut and paste from the JB Industries website. You forgot to insert some missing punctuation though.

So the oil absorbs all the non-condensables? Are you sure about that statement?
 
Originally Posted by Linctex
If it is built like most compressors and pumps, a regular ND 30 weight (like that sold for air compressors) would be fine. You can still get it in KY (not in CA)

Otherwise, any good ATF will work fine if it's about the same viscosity.... but I'd definitely lean towards the 30 grade oil

ND 30 air compressor oil is readily available in CA... We sell it at work. We also have something called "high vacuum pump oil" made by Bosch I think.
 
Amsoil ISO100 Compressor Oil

It works great for compressors and suckers(vacuum pumps) for me. It absorbs and deals with water far better than any other oils I've used in those roles.

A town I know, the guy who takes care of the sewage system, I talked him into trying the Amsoil in their sewage lift pumps, and he was thrilled with the results, the dino would turn white and foamy in a month, he's getting 3 months on Amsoil and it's still not dead. It's paying for itself, apparently the pumps are lasting longer too.
 
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