To ensure proper ventilation with explosion-proof fans, static pressure is required to overcome the resistance of the ductwork network and to transport gases and fluids. When explosion-proof fans operate within an actual ductwork network, both static pressure and dynamic pressure are required. The sum of static pressure and dynamic pressure is referred to as total pressure.
Total Pressure – Refers to the total pressure increase specified for the explosion-proof fan, i.e., the total pressure difference between the fan inlet and outlet.
Static Pressure – The pressure exerted by gas on a surface parallel to the airflow. Static pressure is defined as “the total pressure of the ventilation unit minus the dynamic pressure of the ventilation unit.”
Dynamic Pressure – The pressure resulting from the kinetic energy required to move the air flow. The dynamic pressure of an explosion-proof fan is defined as “the pressure represented by the kinetic energy of the air at the fan outlet.” This corresponds to the pressure value at the fan outlet.
Conclusions:
(1) The static pressure of an explosion-proof fan exists only within the ductwork between the fan inlet and outlet, and must equal the resistance of the ductwork. The relative static pressure network at both ends of the ductwork for an explosion-proof fan equals “zero.”
(2) The dynamic pressure of an explosion-proof fan is not consumed in the ductwork at the fan inlet or outlet. If the cross-sectional areas of the ductwork at the fan inlet and outlet are the same, the dynamic pressures at the inlet and outlet are equal. When the cross-sectional areas of the ductwork differ, the dynamic pressures in the ductwork also differ.
