Motorized Butterfly Valve

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 90^o 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 90^o 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 90^o 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 90^o 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: 

1. Single eccentric valve. This is the motorized butterfly valve in which the stem is mounted behind the centerline of the disc. Motorized butterfly valve manufacturers produce this valve such that it can reduce the contact between the disc and the valve seal before it closes completely. 
2. Double eccentric valve. This is the motorized butterfly valve in which the stem is installed behind the disc with an additional offset at one side. This valve allows the disc to adjust itself to the centerline. This helps to enhance a tight seal. The valve uses soft seats and does not make contact with the valve stem. Due to the soft seats, this motorized butterfly valve can be used in low temperatures applications only. 
3. Triple eccentric valve. This is a motorized butterfly valve designed for use in critical applications. Motorized butterfly valve manufacturers design this valve similar to the double eccentric butterfly valve. This valve has three offsets with two of them similar to those of the double offset type while the third offset arises from the contact axis of the seat and disc. Motorized butterfly valve manufacturers design this valve with metallic seats making them suitable for high temperature and pressure applications. Also, such design helps to reduce wear and enhance working efficiency. 

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 

• These valves are used in mining applications. 
• They are used in water supply and water treatment applications. 
• Motorized butterfly valves are used in the refinery of petroleum products. 
• They are used in the paper and pulp manufacturing industries. 
• These valves are used in chemical manufacturing industries.
• Motorized butterfly valves are used in slurries and sludge applications. 
• They are used in steam and boiler applications. 
• These valves are used in food and beverages applications because they can easily be cleaned to make it easy to maintain high levels of hygiene. 
• They are also used in pharmaceutical applications due to their ease of cleaning. 

Advantages of motorized butterfly valves 

• These valves are automatically operated thus they do not need a valve actuator. 
• They are easy to operate as they need a quarter turn to open or close. 
• Motorized butterfly valves are versatile as they can be used in different industrial applications. 
• These valves are easy to install, clean, and repair. 
• Motorized butterfly valves are less expensive compared to other valves like globe valve and gate valve. 
• They have low-pressure drops. 
• Motorized butterfly valves are simple and compact in design. 

Disadvantages of motorized butterfly valves 

• These valves open with the disc remaining in the fluid flow path which then reduces flow pressure. 
• These valves are more expensive compared to the manual types. 
• Motorized butterfly valves do not have good sealing properties like ball valve. 

Troubleshooting motorized butterfly valves 

Internal fluid leakage 

• Materials clogged in the valve. Open the valve and remove any materials clogged. Clean the valve seat. 
• Damaged seats. Replace the seats. 
• Worn-out O-rings. Replace the O-rings. 
• Damaged disc. Replace the disc. 

External fluid leakage 

• Loose bolts. Tighten the bolts to the torque recommended by the motorized butterfly valve manufacturer. 
• Worn-out gasket. Replace the gasket. 

The valve does not start 

• Power failure. Check that there is power from the power source. 
• Loose connection. Check the connected cables to ensure the flow of electricity. 
• Incorrect frequency or voltage. Ensure the frequency and voltage match the values recommended by the motorized butterfly valve manufacturer. Measure the voltage to ensure it is as recommended. 

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 90^o 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.