The new trestle-design GKHB 5.5kW backward curved fan module combines an ECM with the high-efficiency Rosenberg B-Wheel impeller for even greater efficiency and easy installation. The new B-Wheel Trestle Module features a standard flexible duct connection. The GKHB Series is available in 450-, 500-, and 560-millimeter impeller sizes, offering maximum airflow of up to 10,000 cfm at free air or 3,000 cfm at up to 7 inches of static pressure. Flexible duct connections comply with the customary industrial standard nominal sizes. Applications include data center cooling, HVAC, air-handling units, and air quality products. The GKHB backward curved radial fans employ an electronically commutated external rotor motor with integrated power electronics. These fans feature extended-life, low-temperature brushless dc motors. Rosenberg ECMs come with a pre-installed potentiometer and provide variable fan-speed control from 5-100 percent. Air volume can be adjusted to any possible operating point. Standard voltage for the GKHB Series is 3~ 380-480VAC, 50/60Hz. The motors are UL-recognized. The unique B-Wheel impeller features a seven-blade design in which the blade diameter is smaller than the outside diameter of the cover and support plate, allowing it to act as a rotating outlet diffuser.