Applications for an Offset Butterfly Valve
An offset butterfly valve is able to manipulate the movement of process media through a pipeline in a system. This manipulation is necessary for controlling the amount of media that passes through a pipeline from one location to another, or whether any amount of media is permitted to pass through at all. An offset butterfly valve can also throttle the amount of flow, and only allow a certain volume of media to pass an opening at a given time.
When process media is passing through an offset butterfly valve, there will always be some type of drop in pressure and volume. This occurs because the disc of the butterfly valve itself is still present in the stream of flow. When the disc is shut, it is perpendicular to the pipe and creates a seal that the media cannot pass. When the disc is open, it is parallel to the pipeline, and the media within the pipe system can continue to flow past by moving through the space created on either side of the disc itself.
An offset butterfly valve is available in a wide variety of different sizes, which can be customized to specific systems. The most common size requests range from a few inches to a few feet, but larger valves can be made for a particular system. The size needs to be correctly determined, because the disc needs to be able to adequately cover the entire opening within a pipe in order to create an effective seal.
An offset butterfly valve is a type of quarter-turn valve, which means that in a 90° turn the valve can be moved from the open position to the closed position. Systems that require quick shutoff will benefit from this design.
In conditions that are under a great deal of pressure, the triply-eccentric, or offset butterfly valve, is the best choice for implementation. The offset butterfly valve has a metal seat in its design, which allows it to withstand more pressure than the valves that are comprised of a rubber seat, or a seat from another material less durable than metal. When the valve is going into its closed position, the metal disc does not touch the metal seat until everything is lined up for the completely closed position. This prevents the two metal components of the offset butterfly valve from scratching each other during other parts of the process. If complete shutoff is required in more than one direction, an offset butterfly valve can more reliably ensure that those seals created are both tight enough to fend off penetration. Systems that move oil, gas, or other types of chemicals require particularly reliable and tight shutoff, and these systems are often excellent candidates for the type of services that an offset butterfly valve is able to provide. Systems that work with dirty oil or heavy oil also generally employ the use of an offset butterfly valve fixture, as these types of valves are able to help prevent extrusion.
