What is a flanged butterfly valve?

A flanged butterfly valve is a variation of a flanged ball check valve (FB-C) or ball-and-cup type of check valve. The name "butterfly" comes from the shape that the two halves form, which resembles the upper wings of a butterfly.

The two halves form an inverted cone shape, unlike FB-C, which lhas straight sides and only one large inlet and an outlet chamber. The butterfly valve is designed to be mounted flush against a pipe flange. The " blade" upper piece contains the check mechanism and is usually constructed from forged brass for low friction and wear resistance.The lower piece is usually cast iron or carbon steel, with a screw hole to assemble the pipe.

Classification of flanged butterfly valves

The flanged butterfly valves are manufactured using standard technology based on materials such as carbon steel, high-strength steel, stainless steel and mild steel. Flanged butterfly valves can be manufactured with solid or perforated circlips for better sealing capability.

Depending on the sealing surface material, flanged butterfly valves are classified into two main categories. These are soft-sealed flanged butterfly valves and hard-sealed butterfly valves.

Soft-sealed flanged butterfly valves are used when the service temperature is low. The valve body is soft and made from brass or aluminium alloy. The main parts of the valve, such as the bonnet, disc and plug, are made from stainless steel or alloy steel. These parts are treated with different surface treatments to improve their corrosion resistance. The standard seal material is FKM elastomeric rubber with hardness up to 70 shore A.

Hard-sealed flanged butterfly valves are used when service temperaturees are high and corrosive mediums are present. The valve body is made from cast iron or carbon steel and the main parts are made from alloy steel, stainless steel, copper or monel, depending on the application and pressure endurance requirements.

The applications of flanged butterfly valves can be divided into several categories to meet different demands.

1. Oil or gas supply system: The butterfly valve is usually used in oil or gas supply systems to control fluid flow and pressure, such as oil pipe, water pipe and steam pipe etc.

2. Heat transfer system: Flanged butterfly valves are used in heating and cooling systems to control fluid temperature, such as air cooler, cooling water pipe and boiler water pipe etc. These devices are installed on the incoming side of a heat exchanger located inside a building assembly to control the flow of chilled/hot water.

3. Process control system: These devices are used in the process control system to control fluid flow, such as pipelines, water pipelines, compressor air pipelines, etc. These devices are installed on the outgoing side of a heat exchanger inside a buildling assembly to do the same job.

4. Air conditioning unit: The butterfly valve is applied in the air conditioning unit to modify the flow of refrigerants and thereby increase the efficiency of cooling compressor air or other refrigerant systtems while reducing capital investment and electricity costs.

5.Anti-static use: The butterfly valve is also used in anti-static systenns to eliminate the static electricity build-up and reduce the short circuit event of electronic systems.

The flanged butterfly valves are suitable for use in industries such as steam, water, oil, chemicals and food and beverage manufacturing. In addition to its use in refining and production of natural gas, oil and ethanol hydrocarbons, the butterfly valve is also widely used in transportation.