27.7 inhg

Vacuum is measured in inHg or inches of mercury and a true vacuum is anything below zero on this scale...for reference normal atmospheric pressure or air pressure is about 14.7 inHg so anything less than that could be expressed as a vacuum or less than atmospheric pressure if above zero but less than 14.7 inHg...you can measure this with a vacuum gauge that you can get at any autoparts store but you can feel a vacuum as a suction just like your vacuum cleaner....So a vacuum is anyththing zero inHg or below and a partial vacuum is anything between zero and 14.7 inHg.

It is measured in inches of mercury (inHg)

14.7psia = about 30inhg

thus,

let 14.7 be 15 for easier calculations

if 15 psia = 30 inhg then

1 psia = 30/15 inhg

therefore 1 psia = 2 inhg

or 1 inhg = 0.5 psia

so 10 inhg is about 5 psia

hope this helps

15 Degrees C, and 29.92 inHg