Performance Characteristics
Flow Control
The butterfly valve offers precise flow control. The rotation of the disc from 0° (fully closed) to 90° (fully open) allows for a wide range of flow rates to be regulated. The flow characteristics are often linear, which means that a given change in the disc's angle results in a proportional change in the flow rate. This makes it suitable for applications where accurate modulation of fluid flow is essential.
Sealing Performance
Typically, these valves use elastomeric seats such as EPDM (Ethylene - Propylene - Diene Monomer), NBR (Nitrile - Butadiene Rubber), or PTFE (Polytetrafluoroethylene). The seat material provides a tight seal against the disc when the valve is closed. A well - designed seat can prevent leakage even under high - pressure differentials. Many cast iron wafer butterfly valves are designed to provide bi - directional sealing, ensuring reliable performance regardless of the flow direction.
Pressure and Temperature Resistance
Cast iron is a robust material, enabling the valve to withstand moderate to high pressures. Common pressure ratings include PN10, PN16 for European standards, and ANSI Class 150 in the American system. The temperature resistance of the valve depends on the seat material. For example, EPDM seats are suitable for temperatures ranging from approximately - 20°C to 80°C, while PTFE seats can handle temperatures up to 200°C.
Advantages
Cost - effectiveness
Cast iron is a relatively inexpensive material compared to stainless steel or certain alloys. This makes the cast iron wafer butterfly valve an affordable option for many applications. Additionally, its simple design with fewer parts compared to some other valve types contributes to lower manufacturing costs, which is passed on to the end - user.
Compact and Lightweight
The wafer - style design results in a compact and lightweight valve. This is highly beneficial for installations where space is limited, such as in tight industrial piping systems or in buildings with restricted mechanical room space. The reduced weight also eases handling during installation and maintenance, requiring less heavy - lifting equipment.
Quick Operation
With a 90 - degree rotation of the disc, the valve can be rapidly opened or closed. This quick - acting feature is valuable in applications where fast shut - off is necessary, such as in emergency situations or in processes that require frequent on - off cycling.
Low Maintenance
The simple construction of the cast iron wafer butterfly valve means there are fewer components that can malfunction. Regular maintenance mainly involves checking for leaks, ensuring the proper functioning of the actuator (if present), and lubricating the moving parts. Seat replacement, when required, is also relatively straightforward.
Application Scenarios
Water and Wastewater Treatment
In water treatment plants, these valves are used to control the flow of raw water, treated water, and chemicals. They are equally important in wastewater treatment facilities for regulating the flow of sewage, sludge, and effluent. Their ability to handle large volumes of fluid and resist corrosion from water - based substances makes them ideal for these applications.
HVAC Systems
In heating, ventilation, and air - conditioning (HVAC) systems, cast iron wafer butterfly valves are used to control the flow of water or refrigerant. They help maintain the desired temperature and pressure within the system, ensuring efficient operation. The quick - opening and closing capabilities of the valve are useful for responding rapidly to changes in the HVAC system's demands.
Industrial Processes
In various industrial sectors like food and beverage production, chemical manufacturing, and oil and gas processing, these valves are used to control the flow of different fluids. For instance, in food and beverage production, they can regulate the flow of water, milk, or other ingredients. In chemical manufacturing, with the right seat material, they can handle corrosive chemicals.
Power Generation
In power plants, cast iron wafer butterfly valves are used in cooling water systems, steam lines, and other fluid - handling applications. They play a crucial role in regulating the flow of water for cooling turbines, controlling steam supply, and managing the flow of various chemicals used in the power generation process.
Technical Parameters
Size
The size of cast iron wafer butterfly valves is typically specified in nominal diameters (DN) or inches. Common sizes range from DN40 (1.5 inches) to DN1200 (48 inches), although custom sizes may also be available.
Pressure Rating
As mentioned earlier, common pressure ratings are PN10 (10 bar), PN16 (16 bar) according to European standards, and ANSI Class 150 (approx. 2070 kPa) in the American system. The pressure rating indicates the maximum pressure the valve can safely handle during operation.
Temperature Range
The temperature range depends on the seat material. For EPDM seats, it is generally - 20°C to 80°C, for NBR seats - 20°C to 100°C, and for PTFE seats - 100°C to 200°C.
Material
Body: Cast iron, known for its strength and durability.
Disc: Can be made of cast iron, ductile iron (which offers better strength and corrosion resistance in some cases), or other materials depending on the application.
Seat: Elastomeric materials such as EPDM, NBR, PTFE, or FKM (Fluorocarbon Rubber). Each material has its own set of advantages in terms of chemical resistance, temperature resistance, and sealing performance.
Shaft: Usually made of stainless steel, like SS304 or SS316, to ensure corrosion resistance and long - term durability.
Maintenance
Regular Inspection
Regularly inspect the valve for any signs of leakage, damage to the body or disc, and proper operation of the actuator (if equipped). Check the condition of the seat for wear or cracks. Visual inspections can be carried out during routine maintenance shutdowns.
Cleaning
Periodically clean the valve to remove any dirt, debris, or deposits that may accumulate on the valve body, disc, and seat. A suitable cleaning agent and a soft brush can be used. In applications where the fluid contains solids or contaminants, more frequent cleaning may be required.
Lubrication
Lubricate the moving parts of the valve, such as the shaft and the actuator linkages, to ensure smooth operation. Use a lubricant that is compatible with the materials of the valve and the fluid being handled. The lubrication intervals should be based on the manufacturer's recommendations and the operating conditions of the valve.
Seat Replacement
If the seat shows signs of excessive wear or damage, it should be replaced. The replacement process typically involves removing the old seat, cleaning the seat - mounting area, and installing the new seat. Ensure that the new seat is compatible with the valve model and the application requirements.
