What Is Total Vacuum Measured In Inches Of Mercury?

What is the measurement of total vacuum, measured as inches of mercury?
Does it get measured as negative psi ?

One Response to “What Is Total Vacuum Measured In Inches Of Mercury?”

  • goober:

    It is the absolute pressure. One inch of mercury = 0.491161 psi
    It is negative psi if you are thinking of gauge pressure which is zero at normal atmospheric conditions.
    The absolute pressure at normal atmospheric conditions is about 14.7 psi.