Hexane Safe Pumps

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.

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

…hold my beer.

Best way to move cold EtOH from keg to keg?

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

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

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Those pumps have no problem with liquids

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

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I appreciate your concern. I will be purchasing respirators soon, but we do have adequate ventilation because my lab is in a garage bay that used to be a paint booth and we have a 3ft exhaust fan that we run constantly when we are working. We take safety very seriously when working with hexane as I know how volatile it is as a solvent.

Currently I have a cheapo HF rotary vane vac that I have been using for my rotovap. After reading the replies here it seems I should be using a diaphragm vac as I have been having to change the oil in my vac after every run since it is pulling in hexane. As for routing, I planned on getting 2 barbed fittings for my reactor lid that would allow me to connect my vac to one port and have another line going down to my solvent solution.

The reason I don’t do this is because it takes forever to get my reactor up to temp with my heating loop, and mixing the CBD into the solvent would require shoving a kilo of isolate through a 24/40 fitting, or completely disassembling the adgitator and removing the lid. I’d much rather use vac to suck up my solution than have to tear down my reactor before every use. Hope that makes sense

Get on Amazon and order a cheap Teflon diaphragm pump. The happy buy pumps work fine and are under $500. Best way to move Hexane around that I’ve found. Be sure to use anti static hose.

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using a cold trap with a rotary vane pump isn’t optional btw

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Pictures of your reactor please. I’m concerned.

As @roiplek said cold trap isn’t optional when pulling explosive solvent with an electric rotary vane. And if it’s not vented to the exterior of your workspace via frictionless duct and spark resistant ventilation…well then you sir have a ticking time bomb

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