Hexane Safe Pumps

Hempire Building Want to Buy
21

I thought about that, but I already load the reactor at 40C and the bp of hexane is 68C so I didn’t want to have issues with the hexane boiling if I pulled to low of vac. I thought it might be simpler to use the vac pump like a fluid pump and gradually suck the solution in. I’m a noob so I could be wrong.

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22

It’s not going to boil off because the vacuum diminishes as the mixture gets pulled into the reactor. You’re over thinking it

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23

so don’t load warm, problem solved? also it won’t boil much as long as there’s still air in the reactor that can be pumped out.

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24

Okay that makes sense. I really appreciate the insight.

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25

you can pull all the solvent in with a light vacuum, far from deep enough to boil your hexane. i’ve literally done it with hexane and have moved 1000’s of gallons this way without any issue.

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26

If your lab is redneck I’d highly recommend heptane over hexane. You gotta consider your health as well as others before anything

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27

I think hes worried that the warm hexane solution will build up pressure in his reactor before he can complete the transfer.

Should technically be safe using a rotary vane to maintain the vacuum in that case. I wouldn’t do it unless I had the pump exhausted away from any ignition sources.

28

Agreed on this statement!! Please help us understand how your vac pump is routed so we can ensure you are being as safe a possible.

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29

I personally wouldn’t use rotary vane pumps if a diaphragm pump can do the job as well, as they’re generally much easier to service in case something would get into the pump heads and shit can’t contaminate any oil which would have to be discarded.
Also there are variants out there with 8 heads that go way below 1mbar. Vacuubrand has a new dry screw pump (Vacuu Pure 10/10C) that goes to 0.001mbar and is designed to be entirely maintenance free. Imagine that… never have to do any kind of oil change or rebuild again.

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30

Dude. Is your reactor Jacketed? Just load room temp and then heat and stir in the reactor. That’s what they’re for

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31

A TRs21 refrigerant pump? Pretty sure those things don’t like liquid.

32

…hold my beer.

Best way to move cold EtOH from keg to keg?

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33

@pcsyophant isn’t convinced…

I mainly use them for pressure testing, because you can use them as AIR compressors and hit 450 PSI…

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34

The spec sheet for them shows them recovering liquid an order of magnitude faster

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35

I’ve got a trs21 for sale for anyone who wants it. $400 + shipping

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36

Those pumps have no problem with liquids

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37

I still haven’t goten the pleasure of using heptane denatured etoh but I hear It’s the best alternative to using hexane.

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38

TR21s can handle liquid hydrocarbons…So long as you do not cryo chill the liquids by way of a pre-condenser chilled with alcohol/dry ice slurry before pump inlet. I discovered the hard way that hydrocarbons below -45° will quickly destroy a TR21

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39

Have you since tried using ice water? Or some intermediate method to liquify the solvent before it hits the pump? I was concerned about cryo temps damaging the pump. I know they heat the solvent up tremendously as it passes through the pump, is it even practical?

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40

Ya ice water works great or a chiller set to 0°C

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