fans and ventilating apparatus, namely, propeller hood fans, propeller upblast fans, sidewall propeller fans, tubeaxial fans, centrifugal filtered supply fans, air circulators for air cooling, gravity ventilators for allowing natural air flow, louvers, barometric dampers for use with fans and gravity ventilators, grills and registers for fans and ventilators, ridge ventilators, volumatic ventilators

Ventilating Apparatus for Buildings