Donjoy Control Valve: An In-depth Exploration of High-Clean Control Valve Selection
With the advancement of modern science and technology, control valves used to regulate fluid flow have become indispensable in various industries as part of the automation of production processes. For thermal and chemical process control systems, control valves play a pivotal role in ensuring the quality and safety of process media, stable production, optimized control, and cost management for maintenance and repairs. These valves not only serve as effective means of regulation by altering throttling modes but also contribute to energy consumption through throttling.
Taking pharmaceutical plants as an example, high-load operations often lead to issues such as corrosion, erosion, wear, vibration, and internal leakage in control valves. These problems can significantly reduce the service life and reliability of the valves, thereby decreasing the efficiency of the entire production line. In some severe cases, production may come to a complete halt. Therefore, it is crucial for enterprises that prioritize quality and efficiency to carefully select and install control valves to ensure optimal performance.
When selecting a control valve, it is essential to gather comprehensive data on the physical properties of the process fluid, including its composition, temperature, density, viscosity, normal flow rate, maximum and minimum flow rates, inlet and outlet pressures, and maximum pressure drop. Additionally, one must fully understand the structural characteristics, form, and material aspects of the control valve itself, considering technical factors such as flow characteristics, pressure drop, flashing, cavitation, and noise.
01
Control Valve Type Selection
When choosing the valve type, it is important to determine the nominal pressure based on temperature, pressure, and material conditions rather than using Pmax to set PN. The selected valve should meet the required leakage rate, operating pressure difference, medium temperature range, and ambient temperature requirements. Considerations should also be given to the valve's resistance to blockage and corrosion, especially in environments with hard particles, to ensure durability and economic feasibility. Common valve selection sequences include: single-seat valve, double-seat valve, angle-seat valve, ball valve, and diaphragm valve.
02
Actuator Selection for Control Valves
The simplest actuator choice is pneumatic film type, followed by piston type, and finally electric type. Electric actuators offer convenient power drive but are more expensive and less reliable in terms of waterproofing and explosion protection compared to pneumatic actuators. Therefore, pneumatic actuators are generally preferred. For piston actuators, newer and lighter models are recommended over older, bulky designs.
03
Material Selection for Control Valves
The pressure rating, operating temperature, and corrosion resistance of the control valve body should meet or exceed the requirements of the process connection pipeline. Manufacturers' standard products are preferred. For highly corrosive media, appropriate corrosion-resistant alloys should be chosen based on media type, concentration, temperature, and pressure. When selecting lining materials, ensure they are suitable for the working conditions and resistant to physical and mechanical damage. Rubber or plastic-lined valve bodies are not recommended for vacuum systems.
