Sciencemadness Discussion Board - Vacuum pump for distillation etc.

Vacuum pump for distillation etc.

CycloRook - 27-11-2021 at 15:37

I have a rotary vane pump that is used for refrigerant replacement.
This is a basic pump and pulls a 50 micron vacuum.

I have an issue with it. The suction is great it's just that the exhaust end has an oil and noise dampener but absolutely no way of channeling the exhaust. This is almost useless for anything other than water distillation as I would be essentially pumping whatever is in my glassware to my workspace. I don't have a fumehood.

A solution would be to get an inline blower and position it next to the exhaust port.

Ideally I would like to just take 3/4 tubing and rout it out the window.

If you need more pictures just let me know.

Thanks

arkoma - 27-11-2021 at 19:04

I'm not home so can't take a pic, but my Robin air exhausted through the carrying handle. I unscrewed it, screwed in a barbed hose adapter, clobbered up an oil trap and then continued on with an exhaust house ran through the wall to the outside. Presto.

CycloRook - 28-11-2021 at 03:23

I'm thinking to do the same thing. When I take this cap of the pump is very loud. I'm thinking to find some kind of barbed adapter but trying to match threads sounds hard.

BromicAcid - 28-11-2021 at 06:58

You could also make sure you put good traps inline before the pump and then locate it remotely outside your work area.

zerodan - 28-11-2021 at 07:58

Quote: Originally posted by cycloknight19

I have a rotary vane pump that is used for refrigerant replacement.
This is a basic pump and pulls a 50 micron vacuum.

I have an issue with it. The suction is great it's just that the exhaust end has an oil and noise dampener but absolutely no way of channeling the exhaust. This is almost useless for anything other than water distillation as I would be essentially pumping whatever is in my glassware to my workspace. I don't have a fumehood.

A solution would be to get an inline blower and position it next to the exhaust port.

Ideally I would like to just take 3/4 tubing and rout it out the window.

If you need more pictures just let me know.

Thanks

Looks like the standard model. How much did you pay for it?
I have a similar pump and mine exhausts through the oil refiling cap.
Does your pump also produce a white mist when running?
I tried to remedy that by 3D printing the oil cap with a plastic mesh in the middle where I could place cotton to filter the exhaust. Third time was the charm and the threads were a good enough fit, so if you have a 3D printer you can try printing a hose adapter for the exhaust.

CycloRook - 28-11-2021 at 16:11

No white mist. It's completely clean. Maybe if I sit in the plumbing department I'll find something

arkoma - 28-11-2021 at 18:09

the carrying handle on my Robinair was standard US NPT 1/2" i believe. take the cap with you to the plumbing department with you, and find out what it screws into and you have the thread size figured out.

Again, not home so no pics, but i was gifted an old hospital vacuum receiver jar (guess that what you'd call it) that i have in the suction line before the pump. Its size of a gallon pickle jar with a metal screw lid. the line coming IN to the jar I extended to bottom of jar with tubing and I keep a pretty good layer of dry epsom in the bottom; best i can do at the moment for a moisture trap. I usually change the oil about every use too, and cheat and use power steering fluid. Also, in the interest of safety, the jar is in a deep metal drawer of my desk/lab bench that I keep closed as far as I canto contain flying shards of glass in case of an implosion. Pulled 28 inches on it many an occasion.

CycloRook - 29-11-2021 at 13:36

Ok. I might as well document my findings as it may help others.
Tomorrow I'll go to the hardware store.

CycloRook - 1-12-2021 at 05:47

Well the hardware store doesn't have the size I need. The size of the hole is 3/4 but the threads are finer than regular pipe threads

CycloRook - 2-12-2021 at 05:33

Would anyone happen to know what thread size is finer than NPT ?

macckone - 2-12-2021 at 22:00

There are imperial fine threads which aren't normally used on pipe fittings and metric which is generally a finer thread than NPT.
You may want to pick up a thread guage.

arkoma - 3-12-2021 at 09:33

Are they tapered? I also didn'y look, but if the pump is European, most likely metric. If you live in a big enough city, there will be people that sell just bolts.

*Brain Storm*--in the spec sheet for the product should be listed. Probably looking for something in neighborhood of M14 X 1.0 Diameter in mm, and pitch in thread per mm. Also, a machine shop should be able to identify the thread quickly

chemrox - 6-12-2021 at 14:21

Quote: Originally posted by BromicAcid

You could also make sure you put good traps inline before the pump and then locate it remotely outside your work area.

Yes! I don't know what you need to trap but use a trap for two reasons; avoiding vapor in your space and keeping your oil clean. I used acetone and dry ice for my traps. Also, since ventilation seems to be an issue make sure you don't get CO2 narcosis (hypercapnia). Another thing to consider is an aspirator pump. You would get a better result than using a simple aspirator. I used one with my rotary evaporators and it worked well for most solvents. Sometimes the addition of ice to the bath helped and although I kept a fresh water flow going through it the water use was much lower than a conventional aspirator. In fact my set up was running the water from the condenser through the pump reservoir

Ubya - 7-12-2021 at 05:40

What kind of pump oil are you using?
Usually vacuum pump oils are sensitive to moisture, so even normal water distillations can harm them and the pump.

I ended up making a closed loop water aspirator for this reason, so i can use my crappy rotary vane pump for less destructive projects