BUTTERFLY VALVES DEFINITION BASIC AND TUTORIALS


A butterfly valve is a quarter-turn valve that controls flow by means of a circular disk pivoting on its central axis.



Recommended
● For fully open or fully closed service
● For throttling service
● For frequent operation
● Where positive shutoff is required for gases or liquids
● Where minimum amount of fluid trapped in line is allowed
● For low pressure drop across valve

Applications
● General service, cryogenic service, high-temperature service, liquids, gases, slurries, liquids with suspended solids

Advantages
● Compact, lightweight, low-cost
● Low maintenance
● Minimum number of moving parts
● No pockets
● High capacity
● Straight-through flow
● Self-cleaning

Disadvantages
● High torque for actuation
● Limited pressure-drop capability
● Prone to cavitation

Variations
● Construction: wafer, lug wafer, flanged, screwed, fully lined
● Style: single offset, double offset, triple offset

Materials
● Body: bronze, iron, ductile iron, carbon steel, low-alloy steel, stainless steel, Monel, nickel alloys, PVC plastic, plastic/elastomer lined
● Disk: all metals, elastomer coatings such as TFE, Kynar, Buna-N, neoprene, Hypalon
● Seat: elastomeric, plastic, nickel plated, stellite, tungsten carbide, ceramic


Special Installation and Maintenance Instructions
● May be operated by lever, handwheel, or chainwheel.
● Allow sufficient space for operation of handle if lever-operated.
● Valves should remain in closed position during all handling and installation operations.

Ordering Specifications
● Type of construction
● Style
● Type of seat
● Body material
● Disk material
● Seat material
● Type of actuation
● Operating pressure
● Operating temperature


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