Abstract: An improved air volume regulator used in HVAC operating at a static pressure below 25 pa. (0.1?w.g.) having a pair of opposing gates facing into the airflow and a V shaped baffle positioned to form two constricting passageways. Air flowing through the passageway generates a light vacuum at its throat and combined with the static pressure differential across the gates urges them towards the baffle and constricts the airflow. A counterbalance spring cooperating with a concave cam and cam follower applies a resisting bias on gates such that the airflow in the regulator remains constant under varying inlet conditions. A variable spring rate mechanism permits the adjustment of the airflow rate over the full operating range using a single counterbalance spring. A cable driven “limited torque” flywheel controls the air volume regulator's propensity to pulsate under unstable inlet airflow conditions.

Abstract: Air control regulators include automatically operated air curtains in which pressure and volume vary depending upon demand. A lever and fulcrum principle is used in this controller with the fulcrum position being variable. The fulcrum position can be adjusted manually or mechanically over a wide range of positions for each size of regulator and this variable location of the fulcrum varies the air flow rate through the regulator by re-positioning the flexible air curtain assembly within the regulator.