Best Vacuum achieved by piston pump

[milena02]

Normally using a piston air compresor,run by a electric motor a vacuum about 3" or 4" Hg absolute value can be reached.
A refrigeration compresor reach the same , using air, not at a refrigeration cicle, of course it is not the best to use

What could be the minumun vacuum or absolute pressure can be reached with a piston pump, handle by hand.

Please see

http://www.eng-tips.com/viewthread.cfm?qid=302086&page=1

I can not get , at any place , the pressure it can be reach by a piston pump handle by hand.

I know that it depend on the on the minumun vol when the piston is at it´s maximun position from the crank saft.

It can be seen at the Torriccelli HG atmospheric pressure meter or baromether, the space over the HG , is at 0.000" Hg absolute pressure.

Thanks in advance

 

[Compositepro]

There is no theoretical limit. It all depends on on the mechanical design of the pump and on how long you are willing to turn the handle. And also how many leaks you have.

 

[milena02]

Hi Compositepro.

Guess there is no leak , the volume to be "vacuued" , is 1 liter, the pump displacement is 0.250 Liter , vacuum have to handle soft and slow.

 

[EdStainless]

I don't see why you couldn't get to a few mm Hg. I have used the hand squeeze piston jobs an bottomed the gage out easily. In fact we used them for vacuum tubes (demonstrations) so it must even be lower than that.

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Plymouth Tube

 

[milena02]

Hi all, thanks for your help.