Butterfly Valves

The "butterfly" valve is a type of pipeline valve that uses a rotating disc as its closing element. Its more formal name is a rotary disc valve.

What type of rotary disc valve to buy?

The Ukrainian market offers a variety of rotary disc valves imported from China.

Steel Flanged Rotary Disc Valve

The steel rotary disc valve is often made from plain cast carbon steel WCB. Steel is stronger and more wear-resistant compared to cast iron, offering high resistance to corrosion and temperature. For optimal cost and weight, the body is often made from slightly cheaper and lighter cast iron, with the disc itself and metal bushings being steel, as they directly contact the medium.

Steel "butterfly" valves are used for water supply systems, and for the transportation of oil products and natural gas through pipelines. They should NOT be used for aggressive alkaline and acidic substances.

Cast Iron Rotary Disc Valve

Cheaper rotary disc valves are made with cast iron discs, and they are also used for water, oil, and natural gas. The main disadvantage of cast iron is its brittleness—the disc can crack from mechanical impact, vibration, or sudden pressure changes. Compared to steel, they are less resistant to corrosion and temperature. These drawbacks can be somewhat compensated by increasing the thickness of the cast iron discs, but this makes the valve assembly heavy.

Cast iron butterfly valves should not be used for drinking water, beverage bottling lines, food products, or pharmaceutical production—iron, manganese, copper, and zinc can leach out of the cast iron, and cast iron can adsorb organic compounds from the product, affecting its chemical composition and taste.

Wafer Type Rotary Disc Valve

All the valves in our catalogue are wafer type—they are installed between two mating flanges of appropriate diameter in a pipeline. The advantage of wafer type valves is their low weight, ease of installation in both horizontal and vertical positions, and high tightness. The cost of the valve itself is lower than that of a flanged valve, but you will also need to buy separate mounting flanges for it.

Flanged Rotary Disc Valve

This type of valve already has flanges on its body for attaching to a pipeline, making it heavier and more expensive. It is NOT recommended to use it for aggressive environments due to the risk of leakage.

Choosing a Butterfly Valve

When choosing one, pay attention to several characteristics:

• Nominal Bore Diameter. DN value determines the required size of the butterfly valve—when selecting a replacement for old pipeline valves, find the DN value marked on the disc or label of the valve or measure the disc diameter in millimetres;
• Repairability. Most often, failure occurs due to wear of seals and the disc, but some designs do not allow disassembly and repair of the butterfly valve. Moreover, even in disassemblable designs, online stores often sell only the valve itself, not its parts, which can create problems in finding spare parts;
• Drive:
  • Manual Drive. The butterfly valve may not be fully open—a stop in an intermediate position allows regulation of the flow rate.
  • Electropneumatic Control. The SC-RAT/RST actuator is a direct piston that turns the disc, and an SV-DN solenoid valve or an electropneumatic transducer (positioner) is used for regulation.
  • Electric Drive. These are motorised valves, equipped with an electric motor and transmission in the SCBF-HL block.