AIRFOIL WHEEL: allows stable operation from wide-open to closed-off. Ideal for clean-air applications such as building ventilation with variable-air-volume system control or clean industrial-gas-handling. Dual aerodynamically designed blade surfaces provide the most efficient design of all wheel types. In addition, the AcoustaFoil design offers a broad peak efficiency range for selection. Because of superior efficiency, AcoustaFoil wheels generate the lowest sound levels over a wide range of performance. Sizes 12 and 15 available in welded aluminum only. Sizes 18 to 73 available in all-welded steel and optional aluminum and stainless steel.

BACKWARD INCLINED WHEEL: Flat, single-thickness, backwardly inclined blades are suited to applications from clean air to those where dust and limited material is present in the airstream and airfoil shapes are not recommended due to material build-up. Peak efficiency point is on the steeply rising portion of the pressure curve and vastly superior  to forward curved and radial wheel designs. Sound levels are the lowest with the most efficient fan selections. Sizes 12 to 73 available in all-welded steel and also optional aluminum and stainless steel. Buildings where large volumes of air are required or where fans must operate against resistance, and may also be installed in duct installations where low static resistance is encountered.

BACKWARD INCLINED WHEEL: Flat, single-thickness, backwardly inclined blades are suited to applications from clean air to those where dust and limited material is present in the airstream and airfoil shapes are not recommended due to material build-up. Peak efficiency point is on the steeply rising portion of the pressure curve and vastly superior to forward curved and radial wheel designs. Sound levels are the lowest with the most efficient fan selections. Sizes 12 to 73 available in all-welded steel and also optional aluminum and stainless steel. Buildings where large volumes of air are required or where fans must operate against resistance, and may also be installed in duct installations where low static resistance is encountered.

Direct drive Arrangement 8 fans offer much of the flexibility of belt driven fans and are even preferred in systems that require large volumes of air and are over 250-300 HP due to drive limitations. A major objection to direct-drive arrangements in the past was the inability to adjust fan speed if system requirements changed. With the advent of variable frequency drives (VFDs) the speed, and therefore performance, of direct-drive fans can now be adjusted  to meet varying requirements. Given the variety of operating speeds available, choices in wheel width, and its effect on wheel safe speed limits, the only cost-effective method for selecting today’s direct-drive fans is software selection fan programs.

Belt driven fans, where the fan wheel is supported by a shaft and bearings and driven by belts, allow for a wider range of sizes and applications, and offer a greater selection of accessories and modifications. However, relative to direct-drive fans, they have a larger footprint for a given fan size and have a higher first cost. Without additional controls, belt-drive fan performance can be easily altered in the field by changing sheaves and belts.