IGV pre-rotates the air before it enters the high-speed impeller to improve the air stream condition, thus achieves a significant improvement of impeller efficiency.

Variable Vane Diffuser (VVD) controls air flow by adjusting outlet vanes. An outlet vane has optimized asymmetrical sectional area that results in the adjustment of airflow area and minimization of outlet air obstruction.

Coordinated IGV and VVD controls make it possible for the blower to adjust flow based on operating requirements while maintaining constant pressure. The flow is adjustable to 45% of max design flow, or even lower, while maintaining high efficiency in entire flow range。