
#1
Dec2712, 12:56 PM

P: 303

Why does the pressure in a compressor have a unit PSI instead pound? If the pressure of a compressor is 10 PSI, would a 10 sq in nozzle cause the pressure to drop to 1 psi?




#2
Dec2712, 05:43 PM

Sci Advisor
P: 5,939





#3
Dec2712, 07:53 PM

P: 45

If you were using a compressor, then as mathman pretty much said, the force would almost certainly be what stays constant and the pressure would therefore decrease if you increased the nozzle area. Increase the nozzle area by 10 times, you reduce the pressure by 10 times, and that relationship is implicit in the math of the P = F/A formula. 



#4
Dec2812, 04:41 AM

P: 768

Why use psi instead of just pound?
In a lot of instances, the pressure stays constant while the force changes depending on the area, so it's appropriate to have a unit describing this phenomenon.




#5
Dec2812, 10:46 AM

Mentor
P: 22,001

Right, and the OP was describing a compressor, in which output is controlled to constant pressure, not constant force.



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