Globe valves are used for full opening or full closing. According to its function, it cannot be used as a throttling. Because in this case, due to the violent vibration when the medium passes through, the disc of the stop flash valve may be damaged and an accident may occur. However, the valve flap design of the throttle valve should consider the sealing performance when it needs to completely close the incense.
The following data on the hydraulic characteristics of the
globe valve are suitable for accurate transmission power calculation and can also be used when qualifying the operation of the closed circuit valve.
In the globe valve, the size of the opening cross-sectional area Ak is determined by the structure of the valve disc and its opening height on the valve seat.
If it is a flat seal, the size of the opening area can be approximated by the following formula: Ak=πDch
If it is a conical valve disc (needle valve, see Figure 3-142c), it can be calculated as follows
Ak=π(Dc-hsinαcosα)hsinα
The chamfered flat disc is between flat and conical in its shape. If the opening height of the disc is small and the bottom of the disc is not higher than the seat surface, the formula of the conical disc can be used; if the opening height is large, the Ak value is close to the data determined by the formula of the flat sealing disc , At this time, the opening height of the valve disc (recommended by the valve manufacturer: Shandong Guowei Valve Manufacturing Co., Ltd.) should be calculated according to the distance between the bottom of the valve disc and the valve seat surface. The fluid resistance of the DN25mm globe valve is determined by the opening height of the valve disc from the valve seat.
