ABSOLUTE, GAUGE, ATMOSPHERIC AND VACUUM PRESSURES

ABSOLUTE, GAUGE, ATMOSPHERIC AND VACUUM PRESSURES. 

            The pressure on a fluid is measured in two different systems. In one system, it is measured above the absolute zero or complete vacuum and it is called the absolute pressure and in other system, pressure is measured above the atmospheric pressure and it is called gauge pressure. Thus :

1. Absolute pressure is defined as the pressure which is measured with reference to absolute vacuum pressure. 

2. Gauge pressure is defined as the pressure which is measured with the help of a pressure measuring instrument, in which the atmospheric pressure is taken as datum. The atmospheric pressure on the scale is marked as zero. 

3. Vacuum pressure is defined as the pressure below the atmospheric pressure. 

    The relationship between the absolute, gauge pressure and vacuum pressure are shown in figure:

Relationship between pressures

Note. (1) The atmospheric pressure at sea level at 15°C is 101.3 kN/m² or 10.13 N/cm² in SI unit. In case of MKS units, it is equal to 1.033 kgf/cm².

(2) The atmospheric pressure head is 760 mm of mercury or 10.33 m of water. 

                               The End.

    Please comment if you have any query.


Disclaimer : An attempt has been made to make this blog error free. If there is any error, please forgive.
       







                                                           Thank you.