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There are many types of control valve bodies, commonly including single-seated straight-through, double-seated straight-through, angle, diaphragm, low-flow, three-way, eccentric rotary, butterfly, sleeve, and ball valves. When selecting a valve type, the following considerations can be made:
Mainly consider factors such as selected flow characteristics and unbalanced forces.
When the fluid medium contains highly abrasive particles in suspension, the internal materials of the valve should be hard.
For corrosive media, it's advisable to choose valves with a simple structure.
When the medium has high and varying temperatures and pressures, valves with valve core and seat materials that are less affected by temperature and pressure changes should be selected.
Flashing and cavitation occur only in liquid media. In actual production processes, flashing and cavitation can lead to vibrations, noise, and shortened valve lifespan. Therefore, valve selection should prevent flashing and cavitation from occurring.
Control valves come in various types with different applications. Therefore, it's essential to choose the appropriate control valve type based on the requirements of the process production.
Pneumatic control valves can be categorized as air-to-open and air-to-close. Air-to-open control valves close during malfunction, while air-to-close control valves open during malfunction. Auxiliary devices can be used to create position-holding valves or to enable self-locking of control valves. This ensures that the valve maintains the same opening degree as before the malfunction occurred.
Air-to-open and air-to-close actions can be achieved through the use of positive and reverse-acting actuator types, as well as the combination of direct and reverse acting valves. Valve positioners can also be used to achieve this.
Different control valve structures have distinct features.
Hydraulic water level control valves automatically open and close pipeline circuits to control water levels. They are suitable for various automatic water supply systems in industrial, mining enterprises, and civil buildings with water towers or tanks. They can also be used for pressure boiler circulation water supply control. These valves are compact, easy to install, highly sensitive upon activation, exhibit low head loss, and prevent water hammer phenomena. Controlled by a small float ball, they significantly improve water tower efficiency. For newly built water towers, the reduced size of the float ball lowers the required height for free-floating, mitigating water tower construction requirements. This design addresses issues present in older-style rod float ball valves, such as their larger size, susceptibility to damage, low working pressure, and excessive water overflow. As a result, this product is well-suited for new water towers and the replacement of older float ball valves.
