Concentric Butterfly Valve Introduction, Classification, How it Works, Application
Concentric Butterfly Valve Introduction
Concentric Butterfly Valve, also know as Zero Offset Butterfly Valve, is the most basic type of butterfly valve design. The stem passes through the center-line of the disc which is further placed in the center of the pipe bore and the seat is the inside diameter periphery of the valve body. The disc is in constant contact with the seat.
This zero-offset valve design is also called “Resilient Seated” or “Rubber Seated” because it relies on the flexibility of the seat rubber to efficiently seal the flow when closed. Concentric butterfly valves are commonly used for low pressure ranges. An advantage of concentric butterfly valve is that the media going through the valve will not contact the body, since the seat is constructed as a sleeve or cartridge inside of the body.
Concentric Butterfly Valve have many benefits over other types of valves, such as economic construction, which consists of fewer components, making it easier to operate and maintain. The wafer design body and the relatively lightweight reduce its costs and installation costs, equipment, pipe support, labor and set – up time.
Classification of Concentric Butterfly Valves
According to the connection method of the butterfly valve, it is divided into different types of concentric butterfly valves:
- Wafer Type Butterfly Valve
- Lug Butterfly Valve
- Double flange butterfly valve
- Butt welding butterfly valve
Wafer Type Butterfly Valve
The wafer type of the butterfly valves was built to keep a tight sealing, protecting against bi-directional pressure differentials, to prevent any backflow in devices that were built for uni-directional flow. This is done by the use of a tightly fitted cap, such as an O-ring, gasket, precisely machined, along with a smooth valve face on the downstream and upstream parts of the valve.
Lug Butterfly Valve
The lug body type of the butterfly valve design is identical to the 3-piece ball valve in which one end of the pipeline can be replaced without impacting the other side of the valve. This can be achieved with threaded inserts, flanges, and two sets of lugs (bolts) that do not use nuts so each flange has its bolts. It is also important to remember that you do not need to shut down the whole device to inspect, clean, repair, or replace the lug butterfly valve.
Double flange butterfly valve
The flanged end type butterfly valve has a flange at both ends of the valve to be attached with pipe flanges. This type of end connection is used for the very large size of the butterfly valve.
Application of Concentric Butterfly Valve
Concentric butterfly valves employ soft sealing material due to which it can only be used in basic (water & wastewater treatment plant), special liquid (chemicals, abrasive liquids, etc), and gases for up to 200 psi and 400degree F.
- Water treatment.
- Water Distribution.
- Water Transmission.
- Aeration System.
- Fire Protection, etc.