Basic Documentation

Room Pressurization Control Application Guide
TOTAL
AIRFLOW
PRESSURE
LAB0189R1
Figure 16. Total Pressure (Force Per Unit Area) Exerted in the Direction of Airflow and the Air
Movement Force.
Static Pressure
In contrast to the force exerted by the wind or air in motion, air at rest can exert a force within
any confined or enclosed space. Compressed air within an inflated tire exerts a force on the
entire internal surface of the tire and the resulting force enables the tire to maintain its shape
even when subjected to a heavy load. The force of air that is not due to its motion is also
expressed in terms of force per unit area but it is termed static pressure. Static pressure is
not the result of air movement. There may be no movement of the air in a tire or in a
compressed air tank, yet air pressure most definitely exists. Unlike total pressure, static
pressure is exerted in all directions as illustrated in Figure 17.
44 Siemens Building Technologies, Inc.