Wafer Type Butterfly Valve 

What is wafer-type butterfly valve?

Wafer type butterfly valve is a type of valve which used for on and off application in different industrial applications. The valve is placed between two pipes and bolts are used to connect the valve and the pipes. This type of valve is also known as wafer style butterfly valve. Wafer-type butterfly valve manufacturers design this type of valve with short-length bodies making it possible for the bolts to cross from one pipe end to the other pipe end. The seal between the pipe flanges and the valve is completed by use of a tightly fitted component like a gasket and O-rings along a flat valve face on the upstream and downstream sections of the valve. Wafer-type butterfly valve manufacturers design this type of valve for bi-direction fluid flow. Also, there are other versions of these valves designed with a seal to prevent backflow in applications that need universal fluid flow. 

Wafer-style butterfly valves are in the class of quarter-turn valves. This means that the valve opens or closes when the valve handle rotates for 90^o degrees. The component used to allow and block fluid flow is a disc. The disc remains within the flow passage which is a disadvantage in that it causes a pressure drop and thus reduces efficiency. Wafer-type butterfly valves have their flow path suitable to handle fluid, sludge, and slurries which makes their area of application very wide. Also, these valves are cheaper and lighter in weight compared to other valves like gate and globe valves. 

Figure: Wafer type butterfly valve.

Components of a wafer-style butterfly valve 

Valve body 

This is the component of a wafer-type butterfly valve that is used to hold internal parts of the valve. The body is made strong using strong materials like nickel alloy, brass, carbon steel, and stainless steel among other strong metals. The body is mounted between two flanges of the pipe. The body is also designed with a bolt head to hold the bolts that connect the pipe and the valve. 

Stem 

This is the component of a wafer-type butterfly valve that is used to connect the disc and the handwheel/lever or actuator. The stem serves to transmit the torque needed to turn the disc to open or close the fluid flow. 

Valve disc 

The disc is the part of a wafer-type butterfly valve responsible for opening and closing fluid flow. Proper working of the disc is very critical as it affects the entire working and efficiency of fluid flow. The disc is connected to the handwheel or actuator via the valve stem. It works by making a quarter turn to open or close the valve. 

Seats

Wafer-type butterfly valve manufacturer design these valves with two seats. The seat provides a surface for the disc to rest on when the valve is closed. This helps to prevent fluid leakage when the valve is closed. The seats are pressed, locked, or bonded onto the body. The seat is made of different materials from metals, polymers, or elastomers. 

Actuator/ handwheel 

This is the component of a wafer butterfly valve that is used to provide the torque needed to turn the stem to open the valve disc. 

Figure: Components of a wafer style butterfly valve.

How does a wafer-type butterfly valve work? 

A wafer-type butterfly valve works by turning the stem. The stem connects the handwheel or actuator to the valve disc. This helps to transmit torque responsible for opening and closing fluid flow. To start the valve, the valve operator turns the handwheel for 90^o degrees in the anticlockwise direction. This rotation of the handwheel transmits torque to the valve disc through the stem. By rotating the stem, the disc rotates allowing fluid flow. The disc rotates in a way to become parallel to the fluid flow which makes the flow passage free from obstruction. To close the wafer-style butterfly valve, the handwheel is rotated in the opposite (clockwise) direction. This makes the disc rotate in the same direction where it fits into the valve seats. The disc becomes perpendicular to the fluid flow ensuring no fluid crosses through the wafer-type butterfly valve. Wafer-type butterfly valves can also be used for throttling applications. In this case, the valve operator turns the handwheel slightly allowing slight fluid flow. 

Figure: Working of a wafer type butterfly valve.

Types of wafer-type butterfly valves 

Manual wafer type butterfly valve 

This is a wafer-style butterfly valve that is operated manually. This type of valve does not have an actuator but rather a handwheel or hand lever. The handwheel or lever is where the valve operator applies the torque needed to rotate the stem to open or close fluid flow as necessary. One advantage of a manual wafer-type butterfly valve is that it is cheaper compared to the actuated types. Also, the manual type is versatile in that the user can add the actuator in the future if found necessary. Manual wafer-type butterfly valves can work when the other valves for example those depending on electricity are not operational due to lack of energy. However, manual wafer-style butterfly valves can be dangerous to the valve operator especially where the valve is working on flammable and or acidic products which in case of any leakage can cause a lot of damage. 

Figure: Manual wafer type butterfly valve.

Electric wafer type butterfly valve 

This is a wafer-style butterfly valve that is powered using electricity. The electricity is converted into mechanical energy. The mechanical energy is responsible for providing the torque that turns the valve disc to either close or open. Electric wafer-type butterfly valve manufacturers design this with an automated system that determines when to close and open the valve. The automated system has different components which are powered by electricity. All the parts of the actuator work together to help the valve in starting and closing fluid flow. One advantage of electric butterfly valve is that electricity is widely available and cheap making them suitable for use in almost all applications. 

Pneumatic wafer type butterfly valve

This is a wafer-type butterfly valve that uses compressed air to start and stop fluid flow. Wafer-type butterfly valve manufacturers design this valve with an automated system that coordinates all the parts of the actuator to determine when to open and close the valve. The Actuator works by converting energy into rotary motion. The rotary motion is used to provide the torque that is used to turn the valve stem and then the disc to open and close the fluid flow. Pneumatic wafer-type butterfly valves produce high amounts of torque due to use of air pressure. These valves are also durable and reliable. Having a pneumatic butterfly valve is advantageous in that the device guarantees high levels of hygiene making it suitable for use in sanitary and food applications. 

Hydraulic wafer type butterfly valve 

This is a wafer-type butterfly valve that uses hydraulic fluid to start and stop fluid flow. This type of valve is suitable for use in applications that need a lot of torque since the hydraulic fluid used produces a lot of energy due to its incompressible properties. Hydraulic wafer-type butterfly valves are reliable and smooth in operation. However, these valves are prone to temperature changes due to the hydraulic fluid used. 

Plastic wafer-type butterfly valves 

This is a wafer type butterfly valve that is made of plastic material. Wafer-type butterfly valve manufacturers are similar to metallic ones. Plastic materials such as propylene and polyvinyl chloride are used to make these valves. Wafer-type butterfly valves are very good for use in very corrosive applications involving acids like hydrochloric and sulphuric acids. This is because such plastic materials are very resistant to corrosion compared to the metallic types. Also, plastic wafer-type butterfly valves are very light in weight compared to metallic ones. The challenge associated with these plastic valves is that they cannot be used in high-temperature applications above 60^o C. Plastic wafer-type butterfly valves can be actuated or they can be manual.

Figure: Plastic wafer type butterfly valve.

Applications of wafer-type butterfly valves 

• Used in municipal water supply systems. 
• They are sued in wastewater treatment services. 
• Slurries and sludge applications. 
• Gas and compressed air applications. 
• Fire protection systems. 
• Oil and petroleum refinery industries. 
• Food and beverage processing plants. 
• Paper and pulp manufacturing industries. 
• Chemical processing plants.

Advantages of wafer-type butterfly valves 

• Simple and compact in design.
• Light in weight compared to globe valve and gate valve. 
• Less amount of materials to manufacture these valves making them less expensive. 
• These valves are easy to install, repair, and do maintenance. 
• Operate quickly as they need just a second to turn the disc to open or close.
• Fewer number of moving parts which reduces wear and maintenance costs. 
• Suitable for use in shut-off and throttling applications. 
• They have less pressure drop which improves working efficiency. 

Disadvantages of wafer-type butterfly valves 

• Wafer-style butterfly valves do not have perfect sealing like other valves, such as ball valve. 
• Disc movement is influenced by turbulence. 
• Pressure drop is high because when the valve is opened the disc remains in the flow path. 

Troubleshooting wafer-type butterfly valve

Fluid leakage when the valve is closed 

• The disc is not fully closed. Turn the handwheel or lever to ensure the disc is fully closed. 
• Seats are worn out or damaged. Replace the seats. 
• The disc is worn out. Replace the disc. 

Fluid leakage between valve and pipe connection

• Loose connection. Tighten the bolts and nuts connecting the pipe and valve to the torque value recommended by the wafer-type butterfly valve manufacturer. 
• Worn out gaskets. Replace the gaskets.

Fluid leakage between the actuator/handwheel and the valve

• Worn out packing. Replace the packing. 

The handwheel is hard to operate 

• Foreign materials clogged the valve. Open the valve and remove obstructing materials. 
• Corrosion inside the valve. Check for corroded parts and clean them. 

Actuated wafer-type butterfly valve does not operate 

• Power failure. Check if there is power from the power source and rectify where necessary. 

Summary 

Wafer type butterfly valve is a type of valve used in shut-off and throttling applications. This valve operates by using a disc that rotates at an angle of 90^o degrees to start or stop fluid flow. Wafer-type butterfly valve manufacturers design this valve with a manual or automatic control mechanism. The choice of handwheel or actuator depends on the customer’s preferences and the torque required to open and close the valve.

A wafer-style butterfly valve is designed to allow bi-directional fluid flow. There are also other versions of this valve designed to allow fluid flow in one direction only. A wafer-style butterfly valve is connected to the pipe using bolts and nuts. The valve is placed between the two ends of the pipe as the valve body is short which allows the bolts to cross from one pipe end to the other end.