If you want to regulate the flow of liquid or a fluid in a controlled system, you need to use a valve.

The most reliable and versatile valve is the Butterfly Valve. They are popular as they are usually lightweight and robust and can be easily installed. Further, they are cheaper than other valves and have longer lives.

Relatively simple, butterfly valves consist of only four components – a body, a seat, a disc and a stem. The disc is generally at the centre of the pipe, closing the pipe when it is perpendicular to the liquid flow. The stem runs through the disc to an actuator on the outside of the valve. When you rotate the actuator, the stem turns a quarter of a circle. It positions the disc parallel to the flow, opening the pipe entirely. You can also achieve a throttled flow by opening the disc partially.

Have a look at the valve components and their variants to understand which butterfly valve you will require.

Valve body material

Butterfly valves are generally made in the following materials. Each has its benefits and use cases.

• Carbon Steel – Although it is relatively cheap, it cannot be used in corrosive environments.
• Stainless Steel – This material is designed for corrosive environments and is highly durable.
• Titanium Alloy – Titanium is the most robust metal for its weight. It is lightweight and corrosion-resistant.
• Aluminum Bronze – This material is especially suited for seawater piping systems as it prevents biofilm formation.

Valve seat

The valve seat is where the disc rests when it is in the closed position. The seats undergo tremendous frictional and impact stresses and thus are designed differently for different uses. The valves meant to withstand corrosion by acids and alkalis, water, alcohol, bleach and chlorine are generally made of EPDM (Ethylene Propylene Diene Monomer). EPDM, however, is unsuited for petroleum-based oils, hydrocarbons, turpentine, etc.

Another popular valve seat material is Teflon (PTFE). It is suited for use with oil and gas and is suited for use with electrical appliances. These seats cannot withstand a vast amount of pressure. Consult your supplier to understand which seat material is best suited for your needs.

Valve actuator

The actuator is the part of the valve that turns the disc. It can be operated manually with handles and gears or automatically with the help of electric, pneumatic or hydraulic force. Automatic actuators are helpful if you need to control the flow precisely and remotely. They also come with manual overrides in case the automatic mechanism fails. Ask your supplier to brief you on the pros and cons of either type and suggest the right one for your use.

Connection type

Wafer style

A wafer style valve is placed between two pipe flanges, and the entire ensemble is connected with bolts. Gaskets, o-rings and valve faces are placed between the pipes and the valve to achieve a leak-proof seal. A wafer style connection is appropriate in case of a unidirectional flow, where it can prevent backflow.

Lug Style

If you need the piping system on either side of your valves to be independent of each other, you will need a lug-type connector. The valve is installed between the two pipe flanges with separate sets of bolts on either side. Ensure that the pressure settings are matched according to whether your valve is a connecting valve or a dead-end service. The former can handle a much higher pressure than the latter.

In conclusion

Butterfly valves are the most versatile valves available in a wide range of pressure ratings. They are cost-effective and easy to maintain. If you need a Butterfly Valve, consult your supplier to evaluate which type of valve will serve you best.