Valves are the unsung heroes in the world of fluid control. They are the mechanical devices that control the flow, pressure, and direction of various systems’ liquids, gases, and slurries. The world of valves is vast, encompassing many types, each with unique functionality, strengths, and weaknesses.
This guide will take you through ten essential types of process valves & flow control that are instrumental in achieving superior flow control. By understanding the fundamental workings and uses of these valves, you can ensure the optimal operation of your systems.
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Ball valves are some of the most common in numerous applications, from home plumbing to industrial processes. They consist of a spherical disc, which is the part of the valve that controls the flow. The sphere has a hole or port through the middle, allowing flow when the port is in line with both ends of the valve.
When the valve is closed, the hole is perpendicular to the ends of the valve, blocking the flow. The handle position usually provides a visual indication of the valve’s status. Ball valves are a popular choice for shutoff applications thanks to their simple design and reliability.
Known for their ability to start or stop the fluid flow (but not regulate it), gate valves are your ‘gatekeepers. The valve operates by lifting a rectangular or circular gate out of the path of the fluid. When the gate is fully lifted, the fluid can pass freely. However, when the gate is entirely dropped, it obstructs the fluid path.
They are particularly useful in systems where a minimum pressure loss and a free bore are required, but they are ill-suited for throttling applications.
Globe valves are excellent for regulating flow within a pipeline. They contain a portable circle type component and a fixed ring seat in a for the most part round body The stem moves the disc away from the seat against the flow when the valve is open and towards the seat when the valve is closed, stopping the flow.
Given their design, they provide more precise flow control and are generally more resistant to wear and tear than other valves.
Check valves are vital to many industrial processes, providing a one-way route for conveying the substance. They allow flow in one direction and automatically prevent backflow (reverse flow) when the fluid in the line reverses its direction. This mechanism is essential to avoiding system damage, contamination, and flow reversal.
Butterfly valves offer an elegant solution to flow control. They are named for the wing-like action of the disc, which pivots around the center when the valve is opened or closed. The disc is positioned in the center of the pipe, and a rod passes through the disc to an actuator on the outside of the valve. Compact, lightweight, and easy to install, butterfly valves are an excellent choice for systems requiring large-diameter valves.
Like ball valves, plug valves are used to stop or start fluid flow. They employ a cylindrical or conically-tapered ‘plug’ to obstruct flow. The plug rotates, aligning its hollow through passage with the pipeline in the open state and perpendicular to the closed state. This design makes plug valves a good choice for shutoff and diverting applications.
These unique valves use a flexible diaphragm to control flow. The diaphragm flexes, rising and falling to allow or prevent fluid from passing. Diaphragm valves are popular in the pharmaceutical, food processing, and brewing industries, where sanitation is paramount, as they allow easy cleaning and sterilization.
Relief and Safety Valves
Safety comes first, where relief and safety valves come into play. These are designed to protect systems from overpressure, which can lead to catastrophic failure. When the system pressure exceeds a specific limit, the valve opens to allow the fluid to escape, thus reducing pressure. The valve automatically closes once the system pressure returns to a safe range.
As the name suggests, pinch valves employ a pinching mechanism to control a flexible tube or sleeve, which is pinched close by a tool to create a seal. Because the fluid only contacts the sleeve and does not come into contact with the valve body, pinch valves are often used in applications where contamination or corrosion of the valve body is a concern.
Last but not least, solenoid valves bring a touch of electromechanical brilliance to fluid control. They use an electric current to generate a magnetic field, which moves the solenoid and alters the state of the valve. Solenoid valves are often employed in fluid-power pneumatic and hydraulic systems to control cylinders, fluid-power motors, or larger industrial valves.
When selecting a valve for your process, it’s crucial to consider various factors. These include the nature of the fluid or gas, the required flow rate, the system’s operating pressure and temperature, and the valve’s compatibility with the system materials. In-depth knowledge of these essential types of process valves, their functionality, and their appropriate uses is critical in ensuring efficient, effective, and safe system operations.