Abstract: The invention provides valves of the type employing a differential pressure regulator and a characterized valve with a mechanism to enhance control of fluid flow independently of system pressure. The valves of the invention are especially suitable for HVAC applications, and provide operation with improved accuracy over a greater flow range with a reduced risk of hunting. In one preferred aspect, the invention provides improvements by the employment in the differential pressure regulator of a diaphragm with a cup arranged to provide a small leakage, thereby dampening the response of the regulator. In another aspect, a baffle is provided to protect the downstream side of a control disk forming part of the differential pressure regulator.

Abstract: The invention relates to reduction gearing (10) for an electrically driven actuator for controlling a gaseous or liquid volumetric flow (98), in particular in the fields of heating, ventilation and air conditioning technology and fire and smoke protection, said reduction gearing (10) being modular. Said gearing consists essentially of primary gearing (12) containing at least one drive motor (20) and secondary gearing (14) with a power take-off (36). In addition, a self-limiter (16) is integrated into the primary gearing (12). The gearing modules (12, 14) are detachably interconnected, in particular various secondary gearing mechanisms (14) can be used for the primary gearing (12). The inventive reduction gearing (10) is advantageously complemented in particular by a modular actuator comprising a modular housing, a modular electronics system (38), a sensor and COM module and a coupling module (28).