Backward curved centrifugal fans          The range presented in this chapter consists of backward curved centrifugal fans. In response to your specific needs, the air flow, power, rotational speeds (multispeed by windings or by controllers), noise level, overall dimensions and finish... of the fans can be specifically defined according to your requirements.    Data sheets             General conditions of use Backward-curved centrifugal impellers are of high efficiency and can be used without a scroll housing. If necessary, they can be installed in circular, rectangular, or scroll shaped housings providing there is sufficient clearance to the side-wall. All performance data contained here in relates to measurements taken with ECOFIT standard inlet and discharge conditions. Any modifications to inlet or discharge will result in changes in the performance data. Special constructions with pre-assembled inlet rings are presented here in. ECOFIT motors are speed controllable by voltage variation, but where electronic controllers are used they must be designed for electric motor duty and be compatible with ECOFIT products. Capacitors must be of the "motor run" type and be of the recommended value, voltage rating, and life expectancy. The purchaser must test for motor total temperature in the application, with the worst operating conditions for the motor. ECOFIT should then validate the test results.