Articles

A Guide to Motorized Butterfly Valve

by Abid Saiyad Abid Saiyad

What is a Motorized Butterfly Valve?

The butterfly valve is powered by an electric motor. A valve disc is responsible for closing and opening fluid flow. A quarter turn of the valve disc starts or stops the fluid flow. Thus, it is referred to as a quarter-turn valve. A disc is mounted on the fluid flow passage. The disc makes a 90o angle to open or close the fluid flow path. Motorized butterfly valves are designed to be simple and compact. The design of this valve makes it stronger and less expensive than other valves. The valve fits between two pipe flanges that are bolted together. The result is a tight connection that does not leak fluid. Various types of motorized butterfly valves are manufactured for different temperatures and media types, ranging from corrosive to non-corrosive. 

Components of a Motorized Butterfly Valve

Valve body

In a motorized butterfly valve, this is the main component that holds all the other parts together. Manufacturers of motorized butterfly valves design this part with strong metallic materials such as titanium alloy, stainless steel, carbon steel, and brass among others to make it strong enough to hold all the parts together. There are, however, other valves made entirely from plastic. Plastic material is strong enough to withstand fluid pressure and the weight of other components. 

Electric actuator

This is the part of a motorized butterfly valve that provides torque to start and stop the valve. The actuator contains an automated system for starting and stopping the valve. The process can also be semi-automated. 

Stem

This is the part of the motorized butterfly valve that connects the actuator to the disc. Furthermore, the stem transmits the power needed to turn the disc and allow or block fluid flow. 

Disc 

The part of a motorized butterfly valve that opens and closes fluid flow. Through the stem, the disc is powered by the actuator. 

Seat 

Motorized butterfly valves use this component to seat the valve disc when the valve closes. The seat also prevents fluid leakage when the valve is closed. The material used to make the seat determines where the valve can be used. 

Gasket 

To prevent fluid leakage between the valve and pipe mating surfaces, this component is used. The material used to make the gasket also determines the valve's application area.

How Does a Motorized Butterfly Valve Work?

A motorized butterfly valve is a quarter turn valve, which means that the valve disc must make a 90o angle to start or stop fluid flow. Upon activation of the actuator, the valve starts allowing fluid flow. Through an electric motor, the main supply power is converted into kinetic energy. To produce the desired torque, the rotational energy of the motor is reduced through a mechanical system. Through the valve stem, this rotational torque is transmitted to the disc. Afterward, the disc rotates 90 degrees in an anticlockwise direction, allowing fluid to flow. Keeping the disc open keeps the fluid flowing through the valve. To close the valve, the actuator rotates 90 degrees in a clockwise direction. As a result of this rotation, the disc becomes perpendicular to the direction of fluid flow, blocking any flow through the valve. Throttling valves are used in applications where the disc opens slightly to allow some fluid flow.

Types of Motorized Butterfly Valves

Concentric Motorized Butterfly Valve

The most common type of motorized butterfly valve is this one. Motorized butterfly valve manufacturers design these valves so that the stem directs to the valve disc. As a result, the stem passes through the disc's centerline. A resilient seat comes with this zero-offset valve stem. The seat material is soft, such as rubber or plastic. Therefore, these valves are used in low-pressure and low-temperature applications. The seat prevents fluid leakage when the valve is closed.

Eccentric Motorized Butterfly Valve

There are many types of butterfly valves, but this is one of the most famous. Manufacturers of motorized butterfly valves produce this valve with a stem offset from the centerline of the disc. Among other applications, these valves are used in slurry, mining, paper and pulp, petroleum refineries, and power plants. Eccentric motorized butterfly valves come in three types:


Single eccentric valve. In this motorized butterfly valve, the stem is mounted behind the centerline of the disc. This valve is manufactured by motorized butterfly valve manufacturers to reduce the amount of contact between the disc and the valve seal before it closes completely. 


Double eccentric valve. The stem of this motorized butterfly valve is installed behind the disc, with an offset to one side. The valve allows the disc to adjust itself to the centerline. As a result, a tight seal is enhanced. Soft seats are used on the valve, and the valve stem does not make contact with them. Because of the soft seats, this motorized butterfly valve can only be used at low temperatures.


Triple eccentric valve. A motorized butterfly valve designed for critical applications. Manufacturers of motorized butterfly valve design this valve similarly to the double eccentric butterfly valve. Two of the offsets are similar to those of the double offset type, while the third offset arises from the contact axis of the seat and disc. Designed with metallic seats, motorized butterfly valves are suitable for high-temperature and pressure applications. In addition, such a design reduces wear and increases efficiency.

Motorized Lug Butterfly Valve

A motorized butterfly valve with threaded lugs on the outside. Rather than using nuts to connect the valve to the pipe, the threaded lugs hold the bolts in place. Therefore, the valve requires two sets of bolts to be connected to the pipe. A valve is connected to two flanges by bolts on each flange. With this design, it is easy to remove one side of the piping system without interfering with the other. These valves are recommended for dead-end applications with low-pressure ratings by manufacturers of motorized butterfly valves. Depending on the material used to make the seals and seats, these valves can withstand high temperatures.

Motorized Wafer Butterfly Valve

A motorized butterfly valve employs a design that makes it cheaper than other valve types. This valve is designed to clamp between two flanges of the piping system. Some manufacturers of motorized butterfly valves design them with flanged holes outside the valve body, while others do not. The valve is connected to the pipe by long bolts that cross the valve body from one end to the other. Pipe and valve mating surfaces are sealed with a gasket to prevent fluid leakage. Between the stem and the valve body, O-rings prevent fluid leakage.

Plastic Motorized Butterfly Valve

One of the motorized butterfly valves is made entirely of plastic. Like other butterfly valves, these valves operate on the same principle. For the valve to withstand the weight of the electric actuator as well as other components, it must be constructed of high-strength plastic. Materials such as propylene and polyvinyl chloride can be used. Due to plastic's inability to withstand high temperatures, this type of valve is meant for low-temperature applications. The weight of this type of valve is much lighter than that of metallic ones. Additionally, the machining of these valves is less energy-intensive than that of metallic ones, so the price is always lower. Manufacturers of motorized butterfly valves recommend these valves for use in corrosive media since they are more corrosion-resistant than metallic valves.

Applications of Motorized Butterfly Valves

  • Valve used in mining applications. 

  • Water supply and water treatment applications use them. 

  • The refinery of petroleum products uses motorized butterfly valves. 

  • Paper and pulp manufacturing industries use them. 

  • In the chemical manufacturing industry, these valves are used.

  • In slurries and sludge applications, motorized butterfly valves are used. 

  • Steam and boiler applications use them. 

  • Food and beverage applications use these valves because they are easily cleaned to help maintain high hygiene standards. 

  • Due to their ease of cleaning, they are also used in pharmaceutical applications. 

Advantages of motorized butterfly valves

  • Because these valves operate automatically, valve actuators are not required. 

  • A quarter turn is all it takes to open or close them.

  • The versatility of motorized butterfly valves enables them to be used in a variety of industrial applications. 

  • It is easy to install, clean, and repair these valves. 

  • The cost of motorized butterfly valves is lower than that of globe valves or gate valves. 

  • They have low-pressure drops. 

  • The design of motorized butterfly valves is simple and compact.

Disadvantages of motorized butterfly valves

  • When these valves open, the disc remains in the flow path, reducing flow pressure. 

  • Compared to manual valves, these are more expensive. 

  • As opposed to ball valves, motorized butterfly valves do not have good sealing properties. 

Troubleshooting motorized butterfly valves

Internal fluid leakage

  • The valve is clogged with materials. Remove any materials clogged in the valve. Make sure the valve seat is clean. 

  • Worn-out O-rings. Replace the O-rings. 

  • Damaged seats. Replace the seats. 

  • Damaged disc. Replace the disc. 

External fluid leakage

  • Loose bolts. The torque recommended by the manufacturer of the motorized butterfly valve should be applied to the bolts.

  • Worn-out gasket. Replace the gasket.

The valve does not start 

  • Power failure. Ensure that the power source is working. 

  • Loose connection. Ensure that electricity flows through the connected cables. 

  • The frequency or voltage is incorrect. Match the frequency and voltage recommended by the manufacturer of the motorized butterfly valve. Verify that the voltage is as recommended.

Summary

Butterfly valves that use an electric motor to operate are known as motorized butterfly valves. The valve converts electrical energy into mechanical energy. The torque necessary to start and stop the fluid flow is provided by this mechanical energy. The butterfly valve disc makes a 90o degree angle to open and close a motorized butterfly valve. Manufacturers of motorized butterfly valves use a simple and compact design that makes them cheaper and lighter than other valves. Bolts are used to connect these valves to the pipe, which are placed between pipeline flanges. From low to high temperatures and corrosive to non-corrosive applications, the material used to make the valve determines the area of application.


Many types of motorized butterfly valves are available from manufacturers, including concentric motorized butterfly valves, eccentric motorized butterfly valves, motorized lug butterfly valves, motorized wafer butterfly valves, and plastic motorized butterfly valves. Some of the applications for these valves include paper and pulp, chemicals, pharmaceuticals, foods and beverages, water supply, mining, and petroleum refineries. A few advantages of using these valves include lightweight, fast operation, simple and compact design, cheaper, versatile, automated operation, small installation area, and easy to install and repair.


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About Abid Saiyad Advanced   Abid Saiyad

47 connections, 1 recommendations, 152 honor points.
Joined APSense since, October 21st, 2022, From Ahmedabad, India.

Created on Nov 11th 2022 00:32. Viewed 331 times.

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