Sciencemadness Discussion Board

Makeshift (slight) vacuum generator

Keras - 16-5-2023 at 01:47

Folks,

if you couldn't use a water aspirator or a vacuum pump, what makeshift contraption would you use to create a vacuum suitable to drive a vacuum filtration?

I was thinking about pouring water in a vanilla plastic box into which the vacuum tubing is inserted. You put the box in the microwave oven, make the water boil, then you seal the box with its lid. As the water cools, a depression forms in the box, that could be used to suck the air out of the filtering erlenmeyer.

Other propositions?



Rainwater - 16-5-2023 at 01:58

They sell these little hand pumps for filtering.....
https://www.homesciencetools.com/product/hand-operated-vacuu...

Keras - 16-5-2023 at 02:44

Quote: Originally posted by Rainwater  
They sell these little hand pumps for filtering.....
https://www.homesciencetools.com/product/hand-operated-vacuu...


Yes, I had already seen those hand pumps. But do they really work and keep working after the first week of use? They say best-seller, but I’m not sure I actually ever met someone who had used one of them! :)

Sulaiman - 16-5-2023 at 04:40

For vacuum filtration :
https://www.amazon.com/gp/aw/d/B07H4R7QNC/ref=sspa_mw_detail...
or similar

For vacuum distillation. :
https://www.amazon.com/gp/aw/d/B08P1XD311/ref=sspa_mw_detail...
or similar

PS both types of vacuum pump have noisy output ports so I pipe the exhaust outside or far from the working area.

[Edited on 17-5-2023 by Sulaiman]

paulll - 16-5-2023 at 08:20

Quote: Originally posted by Keras  
Quote: Originally posted by Rainwater  
They sell these little hand pumps for filtering.....
https://www.homesciencetools.com/product/hand-operated-vacuu...


Yes, I had already seen those hand pumps. But do they really work and keep working after the first week of use? They say best-seller, but I’m not sure I actually ever met someone who had used one of them! :)


Mine's been in use for a couple of years, works well.

Rainwater - 16-5-2023 at 11:28

Quote: Originally posted by Keras  

what makeshift contraption would you use

Missed that on my first read.
Reverse it, apply high pressure to the filter, instead of vacuum.
Use this method to recycle my vacuum pump oil after removing the water with anhydrous MgSO4. Works like a champ until you have a leak and blow hot oil across the room in a jet that can cut sheet rock

B(a)P - 16-5-2023 at 12:03

Quote: Originally posted by paulll  
Quote: Originally posted by Keras  
Quote: Originally posted by Rainwater  
They sell these little hand pumps for filtering.....
https://www.homesciencetools.com/product/hand-operated-vacuu...


Yes, I had already seen those hand pumps. But do they really work and keep working after the first week of use? They say best-seller, but I’m not sure I actually ever met someone who had used one of them! :)


Mine's been in use for a couple of years, works well.


We used to use these for vacuum filtration in the field, the metal bodied ones like this last for years.
The plastic cheaper ones as linked above were found to be variable in how long they lasted and were generally not as efficient.

Lionel Spanner - 16-5-2023 at 12:21

Quote: Originally posted by Sulaiman  
For vacuum filtration :
https://www.amazon.com/gp/aw/d/B07H4R7QNC/ref=sspa_mw_detail...
or similar

For vacuum distillation. :
https://www.amazon.com/gp/aw/d/B08P1XD311/ref=sspa_mw_detail...
or similar

[Edited on 16-5-2023 by Sulaiman]

I use a pump very much like the second for both applications; it cost me £70. It easily and routinely draws a vacuum around 0.05 - 0.10 bar, and could probably go lower if I put a sufficiently cold trap in the line.