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What is a motorized butterfly valve?
This is a butterfly valve that is powered by an electric motor. The closing and opening of fluid flow are performed by a component known as a valve disc. This type of valve makes a quarter turn of the valve disc to start or stop fluid flow. As such, it is referred to as a quarter-turn valve. The disc is mounted on the fluid flow passage. As such, the disc makes a 90o degree angle to open or close the fluid flow path. Motorized butterfly valve manufacturers employ simple and compact designs of these valves. Such design renders this valve strong and less expensive relative to other valves. This type of valve fits between two pipe flanges which are connected using bolts. This results in a tight connection free from fluid leakage. Motorized butterfly valve manufacturers produce various types of these valves for use in different temperatures and media types ranging from corrosive to non-corrosive.
Figure: Motorized butterfly valve.
Components of a motorized butterfly valve
Valve body
This is the main component of a motorized butterfly valve since it holds all the other parts together. To make the body have the strength to hold all the parts together, motorized butterfly valve manufacturers design this part with strong metallic materials such as titanium alloy, stainless steel, carbon steel, and brass among others. However, there are other valves designed of wholly plastic materials. The plastic material is made strong to withstand the fluid pressure and other components’ weight.
Electric actuator
This is the part of a motorized butterfly valve that is responsible for providing the torque needed to start and stop the valve. The actuator contains an automated system that determines when to start and stop the valve. It can also be semi-automated.
Stem
This is the part of the motorized butterfly valve that connects the valve actuator and the valve disc. The stem also serves to transmit the power needed to turn the disc to allow and block fluid flow.
Disc
This is the part of a motorized butterfly valve that is responsible for opening and closing fluid flow. The disc gets the power to operate from the actuator via the stem.
Seat
This is a component of a motorized butterfly valve that serves as the seating surface for the valve disc when the valve closes. The seat also helps to prevent fluid leakage when the valve stops. The material used to make the seat is very key as it determines where the valve can be used.
Gasket
This component is used to prevent fluid leakage between the valve and pipe mating surfaces. Also, the material used to make the gasket determines the area of application of the valve.
Figure: Components of a motorized butterfly valve.
How does a motorized butterfly valve work?
A motorized butterfly valve is a quarter turn valve which means that the valve disc needs to make a 90o degree angle to start or stop fluid flow. The valve starts allowing fluid flow when the actuator is powered on. The power from the main supply goes through an electric motor where it is converted into kinetic energy. This rotational energy of the motor is then reduced through a mechanical system to produce the desired torque. This rotational torque is then transmitted through the valve stem to the disc. The disc then rotates for a 90o degree angle in the anticlockwise direction allowing fluid to flow through the valve. The fluid keeps flowing through the valve as long as the disc is kept open. To close the valve, the actuator rotates for another 90o degrees in the clockwise direction. This rotation leaves the disc perpendicular to the fluid flow direction where it blocks any fluid through the valve. These valves are used to in throttling applications in which the disc opens slightly allowing some amount of fluid flow.
Figure: Working of a motorized butterfly valve.
Types of motorized butterfly valves
Concentric motorized butterfly valve
This is the most common type of motorized butterfly valve. Motorized butterfly valve manufacturer design this type of valve such that the stem directs to the valve disc. As such, the stem goes through the disc centerline. This zero-offset of valve stem comes with a resilient seat. This means that the seat material is made of soft materials like rubber or plastic. As such, these valves are used in low-pressure and low temperature applications. This seat helps to ensure there is no fluid leakage when the valve is closed.
Figure: Concentric motorized butterfly valve.
Eccentric motorized butterfly valve
This is one of the most famous types of butterfly valves. Motorized butterfly valve manufacturers produce this valve with the stem being offset from the disc centerline. These valves are used in various applications such as slurry, mining, paper and pulp, petroleum refineries, and power plants among others. There are three types of eccentric motorized butterfly valves which are:
Figure: Eccentric motorized butterfly valve.
Motorized lug butterfly valve
This is a motorized butterfly valve designed with threaded lugs on the outside of the valve body. The threaded lugs serve to hold the bolts used to connect the valve to the pipe without the use of nuts. As such, the valve needs two sets of bolts to connect it to the pipe. The valve is connected between two flanges where each flange has a separate set of bolts. This design makes it easy to remove one side of the piping system without interfering with the other side. Motorized butterfly valve manufacturers recommend the use of these valves for dead-end applications with low-pressure ratings. These valves can withstand high temperatures depending on the material used to make the seats and seals.
Figure: Motorized lug butterfly valve.
Motorized wafer butterfly valve
This is a motorized butterfly valve that employs a design that makes it cheaper relative to other valve types. This valve is designed so that it can be clamped between two flanges of the piping system. Motorized butterfly valve manufacturers design some of these valves with flanged holes outside the valve body while the others do not have the flanged holes. The valve is connected to the pipe by having long bolts that cross from one pipe end to the other end crossing the valve body. A gasket is mounted between the mating surfaces of the pipe and valve to prevent fluid leakage. O-rings are used to prevent fluid leakage between the stem and the valve body.
Figure: Motorized wafer butterfly valve.
Plastic motorized butterfly valve
This is one of the motorized butterfly valves that is made of wholly plastic material. These valves operate on the same principle as the other butterfly valves. The plastic material used to make this valve must have high strength to make it withstand the weight of the electric actuator as well as other components of the valve. Such materials include propylene and polyvinyl chloride. This type of valve is meant for use in low-temperature applications because plastic materials cannot withstand high temperatures. This type of valve is very light in weight compared to the metallic ones. Also, machining of these valves consumes less energy compared to the metallic ones and thus the price is always cheaper. Motorized butterfly valve manufacturers recommend these valves for use in corrosive media since they have high corrosion resistance compared to metallic ones.
Figure: Plastic motorized butterfly valves.
Applications of motorized butterfly valves
Advantages of motorized butterfly valves
Disadvantages of motorized butterfly valves
Troubleshooting motorized butterfly valves
Internal fluid leakage
External fluid leakage
The valve does not start
Summary
A motorized butterfly valve is a valve that uses an electric motor to power its operations. This valve converts electrical energy into mechanical energy. This mechanical energy provides the torque needed to start and stop fluid flow. Motorized butterfly valves are quarter-turn valves meaning that the valve disc makes a 90o degree angle to open and close the fluid flow. Motorized butterfly valve manufacturers employ a simple and compact design that makes these valves cheaper and light in weight relative to other valves. These valves are connected to the pipe using bolts where the valve is placed between pipe flanges. The material used to make the valve determines the area of application ranging from low to high temperature and corrosive to non-corrosive applications.
Motorized butterfly valve manufacturers design various types of these valves which include concentric motorized butterfly valves, eccentric motorized butterfly valves, motorized lug butterfly valves, motorized wafer butterfly valves, and plastic motorized butterfly valves. Applications of these valves include paper and pulp, chemicals, pharmaceuticals, foods and beverages, water supply, mining, and petroleum refineries among others. Advantages of using these valves include lightweight, fast operation, simple and compact design, less expensive, versatile, automated operation, small installation area, and easy to install and repair.