Butterfly Valve Development and Application Introduction

Under normal operating conditions, the service life of a rubber sealing seat typically ranges from 15 to 20 years, while a metal sealing seat can last between 80 to 90 years. However, the appropriate choice depends on the specific requirements of the working environment, such as temperature, pressure, and fluid type.

The relationship between the valve opening and flow rate is generally linear, making it suitable for flow control applications. However, its flow characteristics are closely influenced by the piping system's resistance. For instance, even if two valves are installed in pipes of the same diameter and configuration, differences in pipe loss coefficients can result in significant variations in flow performance.

When the valve is partially open, especially at larger throttle positions, cavitation can occur on the backside of the disc, potentially causing damage. Therefore, it is generally recommended to operate the valve outside of the 15° range to minimize such risks.

At intermediate opening positions, the shape of the flow passage formed by the valve body and the butterfly plate is centered around the valve shaft. One side of the disc moves in the direction of the water flow, while the other side experiences opposite flow. As a result, one side of the valve creates a nozzle-like opening, while the other resembles an orifice. The nozzle side experiences a much higher flow velocity compared to the throttled side, which can create negative pressure on the throttled side. This pressure imbalance can cause the rubber seal to separate or fail over time.

The operating torque of a butterfly valve varies depending on the degree of opening and the direction of movement. For horizontal butterfly valves, especially those with large diameters, the effect of water depth and head difference between the valve shaft and the flow must be carefully considered. Moreover, if there is a bend upstream of the valve, it can create a skewed flow, increasing the torque required. At intermediate openings, the actuation mechanism often needs to include a self-locking feature to counteract the torque exerted by the flowing water.