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Topic: Combined cold trap and vacuum unit  (Read 615 times)

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Offline dejswa

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Combined cold trap and vacuum unit
« on: October 25, 2023, 05:16:51 PM »
I'm considering proper rigging for a rotary evaporator. I need a general answer and I'm not specifying any particular solvents or materials but wondering how this device suits the application. I have a high level dual vac unit that is likely more suitable for vac distillation and not stripping solvents in a rotovap. I do not have a solvent resistant pump. I see these frequently on ebay and elsewhere and it appears to be a combined vac and cold trap. I do not want the burden of needing to source dry ice for a cold trap. I realize dry ice is < -70C and this one specs -55C.

Do you ever use a combined device such as this? Seems quite convenient to have both features in the same unit.

Thermo Savant UVS800DDA-115

https://www.ebay.com/itm/235259186256?hash=item36c68a4c50:g:v3IAAOSwoVplMA-9

I don't find data on the pump specs but the temp seems good. One would need a glass trap that fits the machine, I suppose.

Offline rolnor

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Re: Combined cold trap and vacuum unit
« Reply #1 on: October 26, 2023, 03:09:51 AM »
-55 is very good, no problem. You should not use full vacuum on the pump unless you evaporate DMSO or DMF. You can have a little heat on the waterbath and use around 5-10mmHg

Offline dejswa

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Re: Combined cold trap and vacuum unit
« Reply #2 on: October 27, 2023, 08:35:52 AM »
Thanks for the reply.

Any thoughts on an electric cold trap. Never heard of anyone actually using one. Wondering if I might find some issues with using one. Generally I hear about using dry ice and acetone.

Also I can't really tell if this machine actually has the pump contained within. When I go to the website, I repeatedly see this. machine paired with a separate pump, which would not make sense. When I call Thermo I can never get through their phone mail system to a real person. I leave messages and email and . . . no reply.

Offline rolnor

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Re: Combined cold trap and vacuum unit
« Reply #3 on: October 28, 2023, 04:59:21 AM »
Its just a refrigerator? Dry ice evaporates, you have to add more and thats tedious. If it gives you -55 thats really usefull. You can use a aspirator also but then you need more heat, say 50degrees in the waterbath, thats normally no problem, I have used that for a lot of chemistry. If you see a separate pump, then I dont think a pump is included. There are cheap pumps used for refrigerant istallations on ebay, even pre-owned. They can do the job.

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