A traditional full port ball valve has a large flow coefficient (Cv) in relation to its size. This means that the valve will supply the full required flow when it is only slightly open, thereby utilizing just a small portion of its operating range. Stable control is difficult to achieve - a slight change in valve position results in a large change in the heating or cooling output of the controlled device.
Characterized Control Valves (CCV) feature a disc fitted inside the inlet port. One side of the disc is concave and matches the surface of the ball. Flow is controlled by the opening in the ball and by a specially designed opening in the disc. This reduces the flow coefficient (Cv). The valve increases flow slowly, especially when it begins to open. Therefore, equal percentage flow characteristic is provided and the resulting heat output is linear.
Better valve control prevents “hunting” of the control loop in which the system is constantly adjusting itself to maintain set point. When the operating conditions of the actuator are improved and the full operating range is used, system life span is increased, and energy consumption is reduced.
Belimo now offers a new generation Characterized Control Valve from 1/2"to 2"offering higher delta P (50 psi) and higher media temperature 250°F [120°C].