Valves are integral parts of pipe systems that transport vapours, gases, liquids, and the like. Butterfly valves control the flow rate of a fluid. You can use it for various fluids, like sludge, oil, pharmaceutical fluids, and food products. Valves ensure a robust sealing system. You can find a butterfly valve in lugged, flanged, and wafer types. They are available as electric or pneumatic and manual activation. Here are some points to consider while investing in these types of valves.
Know About the Different Kinds of Butterfly Valves
This valve comes in three basic types: damping, high-performance, and elastomeric seat valves.
- Damping valves – They do not have a valve seat. The valve disc does not touch the interior wall of the body. The valve decelerates the fluid in the pipe. It’s because there’s a gap between the inner wall of the valve’s body and the outside disc diameter. Suppose you want to control gaseous fluids and need a valve for low-pressure applications. In that case, damping valves are a suitable option.
- High-performance valves – These valves utilise a metal seat or rugged PTFE. These valves are made with triple or double biased discs. The valve shaft doesn’t travel through the valve seat and the valve disc centre line. It enables the disc to enter the seat via the cam configuration. It, in turn, minimises the requirement of torque for switching the valve. These valves are suitable for throttling control and shut off. They can handle many things, from general applications to corrosive gases, steams, and liquid.
- Resilient seat valves – It consists of a rubber seat between the interior wall of the body and the external diameter of the valve disc. The seat is attached mechanically to the body. Resilient seat valves have a positive pressure shutoff. They can manage higher pressures and are suitable for sanitary services and toxic media.
Know about the Material That Will Be in the Valve
- Gas – Valves for gas systems firmly seal until a specified leakage rate at rated operating pressures and temperatures. In the case of small volumes, equal percentage characteristics are suitable. For more significant volumes, the linear characteristic is more appropriate.
- Liquid – Valves for liquid systems need firm seals for preventing leakage. You can use linear characteristics if more than 25 per cent of system drop is a possibility at conditions of maximum flow. But if less than 25 per cent of system drop is probable at conditions of maximum flow to the valve, use the linear characteristic.
- Solids – A disc that closes on dry bulk material will cause the rubber seat to wear early. Other factors to consider is disc jamming on dry material and the material getting trapped between the seat and disc and thus causing line inefficiencies.
Understand the Pressure Drop
Pressure drop means the modification in pressure between the valve’s inlet and outlet. It’s an essential specification to know while choosing the required size of the valve. If the pressure drop throughout the fully opened valve is not big, there will not be much fluid flow until the valve closes. So, a fast-acting valve will be appropriate. While selecting butterfly valves for a control system, remember that the valve should absorb 25 to 50% of the entire system pressure drop.
Sizing of the Valve
The particular viscosity and gravity of the media will impact the rate of flow. The second factor is the maximum inlet temperature and pressure and the outlet pressure at the highest load. The last is the highest capacity and the maximum pressure drop that the valve should close against.
Reduction in pipe size impacts the flow qualities and minimises the rate of flow of the valve.
You can use butterfly valves in numerous applications, as they can be controlled with multiple media types. Look for a butterfly valve with a 12-month warranty, which has also undergone strict quality controls. It ensures that the valve doesn’t have any issues.
Author Name: Hannah Gilbert