What is a wafer butterfly valve?

This is a butterfly valve that is sandwiched between two pipe ends. The pipe ends are in terms of flanges with holes. Long bolts are used to surround the valve body to hold it firmly in its position. The bolts cross the whole valve body. Wafer butterfly valve manufacturers design this valve with or without flange holes on the valve body. Tightly fitted seals such as gasket and O-rings are used between the valves and pipe to enhance leakage-proof connection. Wafer butterfly valve manufacturers produce these valves to operate manually or automatically. The automatic types use actuators to start or stop while the manual types use a handwheel or hand lever. These valves occupy a small space since they are short in length. This property makes the valve light in weight and less expensive. Depending on the material used to make the valve and more so internal components, this valve can be used for low to high temperatures as well as corrosive media.

Figure: Wafer butterfly valve.

 

Components of a wafer butterfly valve 

Body 

The body is the component of a wafer butterfly valve that is used to cover internal parts. The body is usually made of strong metallic materials like brass, nickel alloy, stainless steel, and carbon steel among other strong materials. However, other valves are made of plastic bodies and are meant for use in low-temperature and low-pressure applications.

Handwheel/ actuator

Handwheel is the component where the operator applies force to start and stop the valve by making a quarter turn angle. Handwheel is used in manual wafer butterfly valves while the actuator is used in automatic valves. The actuator is designed provide torque to start and stop the valve.

Stem 

The stem is the component connecting the handwheel/ hand lever or actuator to the valve disc. The use of the stem is to transmit torque applied on the handwheel or actuator to the disc.

Disc 

This is the main component of a wafer butterfly valve as it is used to start and stop fluid flow. It gets the power to open and close from the handle/actuator through the stem.

Seat 

A seat is a component used to prevent fluid leakage when the valve is closed. It forms the component on which the disc rests when the valve closes.

Gasket 

This component is placed between the valve and pipe mating surfaces to prevent fluid leakage.

Figure: Components of a wafer butterfly valve.

 

How does a wafer butterfly valve work? 

A wafer butterfly valve is classified as a quarter-turn valve. This means that the valve turns the disc for 90^o degrees to open or close. Both the actuated and the manual valves have the same working principle. To start the fluid flow, the handwheel is rotated in the counterclockwise direction for a 90^o degree angle. This rotation of the handle causes the stem and thus the disc to make the same rotation. As such, the disc becomes oriented collinear to the fluid flow. This leaves the valve open for the fluid to keep flowing. To close the valve, the handwheel is rotated again but in the clockwise direction. This rotation forces the disc to turn and become perpendicular to the pipe where it completely blocks flow through the valve. Wafer butterfly valve manufacturers have designed these valves for both shut-off and throttling use. To use these valves for throttling, the handle and thus the disc is rotated for an angle of less than a quarter turn to allow some level of fluid flow through the valve.

Figure: Working of a wafer butterfly valve.

 

Types of wafer butterfly valves 

Manual wafer butterfly valves 

This is a wafer butterfly valve that is operated manually. The manual control mechanism is the handwheel or hand lever and the valve operator applies force to open/close the valve. Compared to the automatic wafer butterfly valve, this valve is cheaper. This valve is suitable for use where electricity or another source of power is not available or would be expensive. Manual butterfly valve manufacturer design some of these valves with a gear system. This design is meant to help change the torque along the horizontal axis to the vertical axis. The torque along the horizontal axis comes from the handwheel and it has to change direction to move vertically downwards to the disc hence the use of the gear system in the gearbox. The gearbox is placed on top of the valve stem. Despite manual wafer butterfly valves being cheaper and convenient to use, they are risky to the operator in case of leakage and hazardous fluids. Also, it may be so tiresome for the operator if a lot of torque is needed where the valve has to start and stop frequently.

Figure: Manual wafer butterfly valve.

Electric actuated wafer butterfly valve 

This is a wafer butterfly valve that is operated using an electric actuator. Wafer butterfly valve manufacturers design the actuator with an automated system to help in determining when the disc closes and opens fluid flow. These valves operate using mechanical energy. As such, the valve is designed with an electric motor that converts electrical energy to mechanical energy in terms of torque. The actuator is connected to the valve stem so that it can get the torque needed by the valve. Electric actuated wafer butterfly valves can be installed in all industries because electricity is readily available. However, an electric actuated butterfly valve is expensive compared to the manual one. Repair of the valve is also expensive because of the electrical components like a motor which is expensive to replace. However, the advantages of this valve greatly outweigh the disadvantages since the valve relieves the user of fatigue unlike manual types.

Figure: Electric actuated wafer butterfly valve.

Pneumatic wafer butterfly valve 

This is a wafer butterfly valve that operates using a pneumatic actuator. A pneumatic actuator is one that converts energy of compressed air into mechanical energy needed to run the valve. A pneumatic actuator has other names such as air cylinders, pneumatic cylinders, and air actuators. Wafer butterfly valve manufacturers design this valve to rely on compressed air which enters a chamber to build up pressure. Once the pressure exceeds a certain pressure level exceeding the atmospheric pressure outside the chamber, it creates controlled mechanical energy in terms of torque. This pneumatic butterfly valve is versatile as it can be used in different industrial applications involving corrosive and food products. The compressed air can be cleaned before being used to run the valve and thus enhance high levels of hygiene.

Figure: Pneumatic wafer butterfly valve.

Hydraulic wafer butterfly valve 

This is a wafer butterfly valve that operates using a hydraulic actuator. The hydraulic actuator operates by using hydraulic liquid. This actuator helps to change hydraulic liquid’s pressure energy into kinetic energy in terms of torque needed to start and stop the valve. This valve is suitable for use where high torque is required since it is more efficient in producing torque because of the incompressible properties of the hydraulic liquid. However, wafer butterfly valve manufacturers recommend use of this valve where there is low temperature since the hydraulic fluid can be affected if the temperature is high. Also, in case the hydraulic fluid leaks, it causes a lot of contamination which is undesirable in industries like foods and beverages and pharmaceuticals processing.

Figure: Hydraulic wafer butterfly valve.

Plastic wafer butterfly valve 

This is a wafer butterfly valve that is made of plastic material. There are various plastic materials used by wafer butterfly valve manufacturers to make this valve among them polyvinyl chloride and propylene. This valve is made for use in very corrosive media and which is at low temperatures. Plastic wafer butterfly valve manufacturers recommend this valve in such applications because they are much more resistant to corrosion compared to metallic types like stainless steel. Plastic materials are also cheaper compared the metallic ones. As such, this valve ends up being cheaper compared to the metallic wafer butterfly valves. The design employed to make this valve renders it strong to make it withstand fluid pressure as well as the impact of falling objects.

Figure: Plastic wafer butterfly valve.

 

Applications of wafer butterfly valves 

• Wafer butterfly valves are used in fire protection systems.
• They are used in the manufacturing of chemicals.
• They are used in municipal wastewater treatment and water purification.
• Wafer butterfly valves are used in heating ventilation and air-conditioning (HVAC) systems.
• They are used in the processing of foods and beverages.
• These valves are used in petroleum refineries.
• Wafer butterfly valves are used in mining applications.
• They are used in the pharmaceutical industries as they can easily maintain high levels of hygiene.

 

Advantages of wafer butterfly valves 

• These valves can be automatic or manual.
• Wafer butterfly valves are cheaper compared to other butterfly valves.
• The use of quarter turn to open and close fluid flow makes these valves fast operating.
• Wafer butterfly valves are made of simple and compact design.
• They are of small size and thus light in weight.
• Their small sizes leads to small installation space in the piping system.
• Wafer butterfly valves are easy to clean, install and repair.
• Their design makes them versatile and hence applicable in various industries.
• These valves can allow bi-directional or uni-directional fluid flow.
• They are resistant to corrosion and abrasion wear.
• Wafer butterfly valves can be used in slurries and sludge applications.

 

Disadvantages of wafer butterfly valves 

• Wafer butterfly valve seals are weak compared to other valves which may cause leakage in case of high pressure.
• They contribute to pressure drop because the disc remains in the fluid flow path when the valve is open.
• Their design makes them prone to choking and cavitation.
• The closing and opening of the valve disc is influenced by fluid turbulence.

 

Troubleshooting wafer butterfly valves 

The wafer butterfly valve does not close completely 

• Foreign materials in the valve. Open the valve and remove the materials. Clean the internal parts of the valve.

Valve is hard to operate 

• Presence of foreign materials in the valve. Open the valve and remove any foreign materials.
• Corrosion in the valve. Open the valve and clean off the corrosion. Ensure the valve is used on the correct type of fluid as recommended by the wafer butterfly valve manufacturer.

External fluid leakage 

• Worn out packing. Replace the packing.
• Worn out O-rings. Replace the O-rings.
• High fluid pressure. Reduce the fluid pressure to the range indicated by the wafer butterfly valve manufacturer.
• Loose bolts. Tighten the bolts.
• Worn out gaskets between the valve and the pipe. Replace the gaskets.

Internal fluid leakage 

• Worn out seats. Replace the seat.
• O-rings worn out. Replace the O-rings.
• Clogged dirt in the valve. Clean the dirt.

 

Summary 

A wafer butterfly valve is a valve that is installed in a piping system by clamping it between two flanges of the pipe. The pipe flanges are connected using bolts. These bolts cross the valve body to the pipe flanges. Wafer butterfly valve manufacturers design this valve with short lengths which makes it possible for the bolts over the valve. This valve is classified as a quarter-turn valve. This means that the valve operates by turning the disc for a quarter turn angle to start or stop fluid flow. The available designs of these valves operate using handwheel/hand lever or actuator. These valves are applicable in different industries. However, for the best service and economical application, the valve has to be used according to the instruction given by the wafer butterfly valve manufacturer.

Wafer butterfly valves are of various types which include manual wafer butterfly valves, plastic wafer butterfly valves, hydraulic wafer butterfly valves, pneumatic wafer butterfly valves, and electric actuated wafer butterfly valves among others. Applications of wafer butterfly valves include HVAC, wastewater treatment, mining operations, food processing, and chemical manufacturing among others. Advantages of using wafer butterfly valves include lightweight, small size, easy installation, cleaning and repair, fast operation, simple and compact design, and versatility.