What kind of a pump is used in creating vacuum

[mihov123]

what kind of a pump is used in creating vacuum in vacuum flasks or thermose. Diffusion pump, Roots Blower, Rotary vane pump

 

[Q_Goest]

Hi mihove. Welcome to the board. The type of vacuum pump is less a factor than the value of the vacuum prior to sealing off your annular space. A vacuum of around 10 micron is typical though I've seen manufacturers say a vacuum as low as 1 micron or as high as 100 micro when warm is acceptable depending on fluid being conveyed. If the fluid is hydrogen or helium for example, any contamination will freeze out and the vacuum will drop to less than 1 micron during operation. Even atmospherics (ei: LN2, LO2, LAr) will generally drop the vacuum to around 1 micron.

Any vacuum pump that can get down to around 10 micron would be acceptable. That covers a lot of different pumps but the best design is to have a roughing pump and a turbo pump or similar arrangement that will get down to 10 micron or less. A roots blower all by itself for example, wouldn't be able to get you down to that level. It might be ok as a roughing pump but it would need to be put in series with another pump. I could see it being used as a great way of getting lots of air out of the annular space in a hurry because a roots blower generally displaces a lot of air for its size and cost, but the final level is the most important measure of a good vacuum system.

 

[mihov123]

thank you for answering
I asked this because I want to make something simillar to vacuum insulated panels, something like a plastic honeycomb core and then create vacuum but now I see that is not simple as I thougt it would be and defineatly much more expensive