experienced per unit area is known as pressure.
Force / Area
pressure is Newton / metre2 or N / m2
– Liquids and gases exert pressure on the walls of the
(pa): The pressure measured above absolute zero
of pressure is called absolute zero pressure. A absolute
zero pressure occurs only in complete volume.
pressure = Gauge pressure + Atmospheric pressure
pg + patm
(pg): The instrument used to measure the pressure
generally measure the difference between the system pressure
and atmospheric pressure. This is known as gauge pressure.
It is difference between the atmospheric pressure and
pressure = Atmospheric pressure – absolute pressure
atmospheric pressure = 1.01325 bar
exerted by the surrounding air is known as atmospheric