A method of constant airflow control includes various controls to accomplish a substantially constant airflow rate over a significant change of the static pressure in a ventilation duct. One control is a constant I·RPM control, which is primarily used in a low static pressure range. Another control...http://www.google.ca/patents/US7915847?utm_source=gb-gplus-sharePatent US7915847 - Method of constant RPM control for a ventilation system
