This company offers two models of centrifugal duct fans. The RIBA belt-drive models are offered in sizes from 6 inches to 15 inches and use standard 1,750-rpm motors. Belt-drive models are designed for quieter operation and lower initial cost, according to the company. The RIDA direct-drive models, available in sizes from 6 inches to 15 inches, require less maintenance. The company claims that they offer longer operating life and reduced operating costs. On both models, the fan housing and motor supports are made of heavy gauge steel plate. The aluminum centrifugal wheel is a non-overloading backward-inclined type, selected for low noise levels.

American Coolair Corp., P.O. Box 2300, Jacksonville, FL 32203; (904) 389-3646;