Is this vacuum pump adequate for my smallscale?

So I’m looking to upgrade my old pump, a Robinair 15500. I’ve had it for 6+ years, no issues other then oil mist and db levels.

My scale is small, I have a 3g and 5g heated vacuum chambers, and a 1 liter vacuum flask.

The pump in question:

I know it can’t pull a full vac, but can it still fully purge winterized material? I’m not a production facility, so if I need to leave my materials in the chamber for longer, then that’s fine. Currently I use my chamber mostly with passive vacuum, I’ll run my robinair for 10~ minutes, lock the chamber and let it set for hours. So while the diaphragm pump doesn’t pull as deep of a vacuum, being oil free and comparatively quiet, I’ll be able to run it longer.

Could I use the diaphragm pump with my vacuum flask because it’s relatively low cfm? I’m debating buying a 2l flask. The pump I have for my vacuum flask is small, while my robinair is too much.

I could use the diaphragm pump if I ever get a rotary evaporator

My goal is to get a pump that not as loud, my robinair is around 80db, and preferably dry as the pump is used in my home and I don’t want oil mist

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6 years …too old, buy a new ,man

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what kind of guages do you use to tell vac level? I have regular compund guages and it goes down to -30 but I dunno if thats a full vac based on microns. It only takes a few mins and I hear you should vac for hours in hvac. I use the sound of the pump to tell more than the guage but im sure my harbor freight pump isnt the best, and its 6 years old.

That is not a chemically rated pump. It is has a neoprene diaphragm and is designed for clean air applications like dental offices, et al.

They do offer it with a Nomex diaphragm ( EPDM) which is chemically compatible to alcohol and hydrocarbons. If the price was right you might switch out the diaphragm.


Full atmosphere is 29.92" Hg and 760,000 microns. Full vacuum is -29.92" Hg and 0 microns.

Compound bourdot gauges able to discriminate between -29.92 and -30" would need a huge face for the scale, so consider it just an approximation. I also noticed that mine periodically required recalibration to zero.


It also occurs to me that I have two or three double diaphragm Gast DAA vacuum pumps with neoprene diaphragms in my treasure pile, one a factory repair and two brand new left over from WolfWurx.

Make me an offer if you decide to go that way.


Im not sure, but I think the one I linked has the nomex diaphragms. When I looked up the part number, their only 29hg pump, under the specs, it lists the wetted parts as “ * Wetted Parts 304 Stainless Steel, Aluminum, Nordel®, Nomex®”

Time will tell, pretty sure my wife ordered one already

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That diaphram pump is great for rotovap and buchner filtration. Your never gonna get a deep vac for a vac oven

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You want to pull a constant vacuum,l not just pull a vac and close the valve.

You could pull a vac and close the valve but you would need to then passively purge the oil… connect a second vacuum chamber and put on ice, put the oil chamber on heat

Let us know how it works out!

Hee hee, snicker, snark, thanks for pushing me to research Gast diaphragms, which gives me some ideas on where I might use my existing pumps!


Glad my idiocy could be somewhat helpful. I’m open to suggestions, especially from master greywolf. We bought it from Amazon, easy enough to return the thing

This is the one I use for vac filtration and rotovap not my oven though. For my oven I use a 12cfm 2 stage rotary vane vacuum pump from ebay and if I’m doing anything etoh related I use my shitty bvv cold trap.

Bust most everyone here prefers a Welch wobi

This is part of the reason I want a quieter oil free vacuum. I want to run the vacuum constantly while purging, but my robinair is too loud and I don’t have a mist filter.

Man, I feel so stupid, I wish I had known quality rotary vane pumps were so quiet. An edwards E2M12 lists its volume as 52 db… that’s significantly less then the gast @ 68db.


I did end up getting this pump as a Christmas present from the wife, couldn’t return/exchange because she does her Christmas shopping in October…

All in all, I’m happy with the pump. It’s all setup and running, quieter, no oil mist. I ended up getting a 4l vacuum flask, and this thing is almost too much vacuum. With the funnel full it pulls a deep vacuum quickly, pulling the etho through the filter so fast it comes out the funnel foamy. Some residual splash will coat the sides of the flask, but the vacuum doesn’t appear to be enough to suck the etho straight into the pump.

I should probably get a regulator for it though. In the photos it appears to have regulator behind the gauge, but mine did not come with one. I believe this is the one they sell, but I cannot find a photo or diagram anywhere

I ran the pump for roughly 30 hours until then oil appeared none reactive. I hooked up my old robinair to see if a deeper vacuum would stimulate a reaction. Roughly 5-10 tiny bubbles appeared, dissipated within moments. While tilting and running the oil side to side, maybe 5 more tiny bubbles came out. Oil was none reactive again within a few minutes. I figure I’ll do most of the run with my diaphragm pump and I’ll finish with my rotary

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You ran the vacuum for 30 hrs on your oil?

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Not consecutively. Like 12 hours the first day, then I killed the heat and vacuum, then another 12 the next day, probably 24 hours total at this point, plus another hour to finish with the rotary.

This is just for friend and family, not production, i would rather run the pump longer then needed and be on the safe side, don’t have any means of testing it

Would running it too long hurt anything?

Do you care about terpenes? You definitely don’t ever need to run vacuum continuously.

I pull mine down to -15 to -20 ish and leave it for 2 days and then call it good.

Anything more and you’re just boiling terpenes out. It’s a delicate game between evap the gas not the terps


I do and I don’t, my main concern is safety since I can’t test my product. I would rather sacrifice terps then hand out product with butane or ethanol in it. This oil is for carts, so I’ll be adding terps back in, I even decarbed in the same chamber.

I use to pull the deepest vac I could with my robinair, seal it off for hours, then pull again like 6-12 hours later, but only for a few minutes. I thought the big guys ran their pumps non stop when purging, heck someone earlier in the thread made a post about it

Plus this is the largest batch I’ve ever done, almost double my usual batch

If I’m making shatter I vac the whole time. I also get the oven to temp and then shut off the heat :upside_down_face: flip and repeat

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