Using Butterfly Valve Actuator For Better Flow Control
Butterfly valves are designed to regulate gas or liquid flow through a disk, the main closing mechanism. This type of valve allows flow though one direction but does not have pockets to contain the liquid when the valve is closed. The presence of the disk within the flow also creates a certain pressure drop. This is why butterfly valves are used in relatively high pressure systems. In addition, the disk’s position increases the sealing capacity of the valve, and prevents leakage. A butterfly valve actuator is a valuable tool that helps the butterfly valve gain complete control of the flow system. While the disk is placed in the center of the pipe, the actuator is situated outside the valve and is connected to a shaft passing through the disk.
An effective butterfly valve actuator must be able to turn the valve disk in a slow manner for every turning position of the input shaft until the disk is in a near closed position. This characteristic will provide the most precise control of the flow and produce the highest torque when needed. When the actuator rotates, it turns the disk into a position parallel or perpendicular to the flow. A butterfly valve actuator can be used in a wide range of applications, and is found in different settings like water treatments plans, refineries and power plants. In most cases, actuators automate the process control. Butterfly valve actuators can have varying designs and dimensions depending on it intended use. The valve size can range from a couple of inches to a few meters. The most common classifications of actuators are electric, hydraulic and pneumatic.
When choosing the right butterfly valve actuator, some important considerations have to be made. Aside from getting the proper size and pressure for the butterfly valve actuator, the type of operating torque must also be considered. The first type of operating torque is the seating torque, which is needed to displace a resilient seat and facilitate effective shutoff. The bearing torque is the second type of torque, suitable for overcoming friction forces on the shaft bearing surface of the valve. The third kind is called dynamic torque, which is required to close a valve that deals with strong fluid forces.
A butterfly valve actuator can be mounted directly to the valve, but there are also other types that may require coupling hardware. The actuator’s material determines its strength, durability and longevity. The best kinds are the ones made with hard anodized materials instead of the thin walled ones. However, some manufacturers produce light duty actuators that cost less to sell specially for domestic purposes. Heavy duty butterfly actuators, which are suitable for industrial applications, are water-proof, can pass long salt chamber tests, and are fitted with double travel stops.
In some cases, one actuator can operate two butterfly valves of the same size. This particular application is called a standard tee linkage. In this situation, one valve is in charge of opening when the second one closes. Finding the right actuator size for a standard tee linkage application uses the same principles as looking for an actuator for a single butterfly valve application.