Industrial Butterfly Valves: Basic Types and Uses
Industrial butterfly valves are suitable for modulating and isolating the flow of liquid and gaseous products, which are often highly corrosive. These valves are made for long heavy duty services, and are used in applications for various industries that involve chemicals, oil and ship building. This valve version is smaller, lighter and useful to regulate flow in piping configurations. Because of their size, they are cheaper and more convenient to install. A number of industrial facilities choose to use butterfly valves because of their positive shut-off and throttling capabilities, which are not necessarily always present in other control valves.
A butterfly valve's basic parts include a body, a butterfly disk, a stem and a seat. The disk is the mechanism that is responsible for allowing the flow to come through the valve, or blocking flow off completely. A number of butterfly valve models are equipped with actuators, which controls the turning of the disks to allow or prevent flow.
The resilient butterfly valve is the type that offers the lowest pressure rating, and capitalizes on the flexibility of the rubber. Industrial butterfly valves can have a single offset, double offset or triple offset construction design. The offsetting style refers to the unconventional positioning of the disk to increase in the valve's sealing efficiency and decrease its vulnerability to tear. The triple offset butterfly valve is regarded as the most appropriate device when dealing with high-pressure systems. This is because the style utilizes a strong and solid metal seat that can endure a great level of pressure. Triple offset valves are also often used in applications that demand bi-directional tight shut-off.
Other common types of industrial butterfly valves are wafer-style and lug-style. Wafer style valves perform the tight sealing function against bi-directional pressure, to eventually deter system backflows. To successfully fulfill this crucial function, a wafer style valve makes use of a tightly fitting seal like gasket or o-ring. Lug style valves, on the other hand, can be installed in the piping system using two set of bolts due to the threaded inserts at each side of the valve body. This is mainly used to lower pressure rating in dead end service.
Butterfly valves can be fabricated in terms of actuation and body designs to conform to particular applications. Other fabrication adjustments that can be done include changing the attachment position for the stem and the disk, and their mounting inside the valve body. These kinds of trim features are provided by a number of top manufacturers. However, when manufacturers construct industrial butterfly valves, they are usually expected to meet at least one of the well-known quality standards like ASME, ASTM and ANSI. Leading butterfly valve models have fire-safe features and come with soft or metal seats. They are also made to work efficiently in both low and high temperature conditions.
Industrial butterfly valves can be used in handling dry material. However if such materials are semi-abrasive or abrasive, and contain particles, then proper care must be taken when using this type of valve. Dry bulk materials can wear out the rubber seat every time the valve disk closes. They can also cause disk jams and line deficiencies by becoming trapped between the seat and disk.
