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Valves are commonly used fluid control devices in industry and agriculture. This article discusses the types and applications of valves, focusing on flow control valves, pressure control valves and safety valves, and their combined use.
Flow Control Valves
Flow control valves are devices used to regulate the flow of fluids in pipelines. Commonly used flow control valves include butterfly valves, globe valves, ball valves and gate valves.
Figure 1. Butterfly valves
Butterfly valves are widely used in many industries, such as water supply, sewerage, industrial cooling, power plant, paper and food industries. It is a simple, lightweight, economical and versatile valve. The inlet flow will influence the pressure drop under various opening modes, but the flow rate remains relatively constant.
Figure 2. Globe valves
Globe valves have a good throttling effect and widely used in chemical, power, oil and gas, sewage treatment, refrigeration and air conditioning, papermaking and other industries for controlling flow. Globe valves can be used for both on/off applications and throttling applications, but the flow rate is variable with changes in pressure.
Figure 3. Ball Valves
Ball valves are widely used for on/off applications. They have simple structure and good performance, and can be used in various mediums. The flow rate is relatively constant under different pressure differences.
Figure 4. Gate Valves
Gate valves are widely used in water supply, electric power and other industries. Gate valves are suitable for on/off and low pressure throttling applications. Gate valves are not suitable for high-pressure dynamic throttling applications as the flow rate is variable with changes in pressure.
Pressure Control Valves
Pressure control valves are used to control the pressure of piping systems. Commonly used pressure control valves include pressure relief valves, safety valves, pressure reducing valves and pressure sustaining valves.
Figure 5. Pressure Relief Valves
Pressure relief valves are used to protect equipment or pipelines from overpressure. If the pressure of a system exceeds the predetermined set pressure, the valve will open and the excessive pressure will be released.
Figure 6. Safety Valves
Safety valves are used to protect equipment from overpressure due to a sudden increase in pressure. They will open to release excess pressure once the pressure reaches the preset pressure.
Figure 7. Pressure Reducing Valves
Pressure reducing valves are used to reduce the pressure of a portion of a piping system. When the upstream pressure increases, the valve will open and reduce the pressure to the preset value.
Figure 8. Pressure Sustaining Valves
Pressure sustaining valves are used to maintain a constant upstream pressure. They will adjust the outlet flow to maintain a constant upstream pressure when it goes beyond the preset value.
Combined Use of Valves
Due to the various types of valves and their various applications, they can be used in combination to meet the needs of a system, such as a pipeline system.
of valves and their various applications, they can be used in combination to
For example, a pipeline system may use a combination of globe valves, safety valves, and pressure reducing valves. Globe valves can be used to correct the flow rate and keep it under control. Safety valves can be used to protect the system from overpressure, and pressure reducing valves can be used to reduce the pressure of a portion of the system.
Another example is a pipeline system that includes a combination of butterfly valves, ball valves, and pressure sustaining valves. Butterfly valves are used to regulate the flow rate, ball valves for on/off applications, and pressure sustaining valves for maintaining a constant upstream pressure.
Conclusion
Valves are often used in combination to meet the needs of a pipeline system. Different types of valves have different applications and can be used in combination to optimize the performance of the system. Flow control valves, pressure control valves and safety valves are the most commonly used valves and can be used in combination to meet the needs of a pipeline system.
