Do You Know the Two Methods for Adjusting the Airflow of Axial-Flow Explosion-Proof Fans?

Do You Know the Two Methods for Adjusting the Airflow of Axial-Flow Explosion-Proof Fans?

Depending on specific operational requirements, it may be necessary to adjust the airflow of an axial-flow explosion-proof fan to meet necessary conditions. Currently, there are two methods for adjusting the airflow of axial-flow explosion-proof fans: air valve adjustment and pneumatic switch adjustment, each with different results. Air valve adjustment and outlet air valve adjustment: The characteristics of the axial-flow explosion-proof fan do not alter the characteristics of the ductwork system. The airflow adjustment range typically covers all operating conditions on the axial-flow explosion-proof fan’s rated performance curve. This method alters the ductwork characteristics by manually increasing ductwork resistance; therefore, the additional resistance created by closing small air valves consumes pressure drop, resulting in less economical operation.Inlet Valve Adjustment: When piping is installed on the suction side of the axial flow explosion-proof fan, the adjustment principle is the same as that for the outlet valve. When piping is installed on the discharge side of the axial flow explosion-proof fan, the fan’s performance curve changes as shown below by altering the inlet pressure. Because it is an axial flow explosion-proof fan, this adjustment method is highly cost-effective. Adjustment using a spiral damper alters the characteristics of the axial-flow explosion-proof fan by modifying the fan’s outlet area. Compared to reducing airflow, the change in power consumption is minimal, and the energy-saving effect is also limited. In principle, these two adjustment methods can be used under all operating conditions within the rated curve, shifting the surge point toward lower flow rates. Therefore, they are widely used in fixed-speed axial-flow explosion-proof fans. 2. Inlet Blade Adjustment: Inlet blade adjustment alters the flow direction at the inlet and the fan’s performance curve by adjusting the blades. Positive-wrap adjustment of the axial explosion-proof fan’s inlet flow allows operation under all conditions along the performance curve when the inlet guide vane angle is zero. Negative-wrap adjustment of the inlet flow may increase the fan’s pressure and airflow, but the adjustment range is limited. Therefore, if it is necessary to adjust the airflow of an axial-flow explosion-proof fan, a more appropriate method can be selected based on the fan’s design and operational requirements to achieve optimal operating conditions without damaging the fan’s main body. Then, to meet those operating conditions, the airflow is increased.