Vacuum formula

[Camdude®]

O.K. Gurus,

i need a formula that will indicate the force generated by a vacuum over an given amount of square inches. we are assuming a perfect seal on the vacuum. any help appreciated.

 

phil teh i can't find my formulas binder.

[Guest CNC Apps Guy 1]

1" of Mercury = .49112 PSI

 

That what you're looking for?

[Fralex_francois]

Maybe this will help , I sometimes need some conversion and there is lots of stuff on this (some funny but useless)

[BernieT]

A perfect vacuum would exert 14.7 pounds per square inch. (1 atmosphere)

 

A 5" x 8" rectangular part with a perfect seal at the edges would have 5 X 8 X 14.7 = 588 pounds of force holding it down.

 

HTH

[Camdude®]

Dang you guys are fast. thanks for the help.

[Travis_Buchanan]

Hey don't forget to throw in a little altitude factor. Not all of us are working at sea level. Travis teh 14.5 psi in teh mountains.

[Harryman]

Remember that you won't get a perfect vacuum so use a number around 60% of your 14.X psi for safety.

 

Pumping volume and conductance are key to maintaining vacuum in the presence of any leaks. Even if the pump is adaquate, the plumbing must be large enough to handle volume at low pressure or a small leak could cause the part to release.

[BernieT]

quote:

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Hey don't forget to throw in a little altitude factor. Not all of us are working at sea level. Travis teh 14.5 psi in teh mountains.

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Good point, what is your altitude? Anybody know what the pressure is at Denver or Santa Fe?

 

[Travis_Buchanan]

Approx 1200 feet. Before I moved down here average elevation was 3500 feet.

[wildcat99]

quote:

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Anybody know what the pressure is at Denver or Santa Fe?

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Denver 12.2 psi

Santa Fe 11.4 psi

 

....approximately

[BernieT]

Wow, did not know it changed so much. Thanks.

[MetalMarvels]

+1 to James. The amount of force applied is dependant on #1 the amount of vacuum you can pull (21 to 24 inches of Hg is pretty good - 27 inches and up is considered "high" to "hard" vacuum), #2 the local pressure (which DOES vary from day to day as well as being dependant on your altitude), and #3 the surface area. Using the figures quoted by James provides a reasonable approximation of what you can expect for holding force. Note that the quoted value is at sea level at standard pressure.

 

quote:

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1" of Mercury = .49112 PSI

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By definition, a pressure that is less than the standard pressure at sea level is considered a vacuum. No wonder it sometimes sucks to live at 6300 feet.....