AB-QM is a Pressure Independent Balancing and Control Valve, which limits the maximum flow, and at the same time function as a control valve operated by a several different types of Danfoss actuators. AB-QM can be set to a precise design value and thereby provide full control over the real conditions in the system.
Control performance the AB-QM has a linear control characteristic. The AB-QM is pressure independent which means that the control characteristic is independent from the available pressure and is not influenced by a low authority. The flow limitation on the AB-QM is achieved by limiting the stroke and the Danfoss actuators calibrate to the stroke of the valves. This means that the AB-QM keeps its linear characteristic regardless of the setting or differential pressure. Because of the predictable characteristic the actuators on the AB-QM can be used to change the response from linear to logarithmic (equal percentage). That makes the AB-QM suitable for all applications, including AHUs, where the equal percentage characteristic is needed to get a stable control loop. The actuators can be switched from linear to logarithmic by changing a dipswitch setting on the actuator.