A concentric butterfly valve is a flow control device that controls the flowing medium in the system using a rotating disk. The disk remains in the passage, but due to its thinness, it provides little impediment to the flow.
Butterfly valves have many benefits over other valves, such as economic construction, which has fewer components, making it easier to operate and maintain. The wafer design body’s lightweight and low-cost cut installation costs, equipment, pipe support, manpower, and set-up time.
A centric or concentric butterfly valve configuration is the most prevalent form of butterfly valve layout. The stem of this sort of butterfly valve travels along the middle line of the disk in the center of the pipe bore, and the seat is inside the diameter of the valve’s body. This no-offset valve arrangement is also known as a resilient-seated valve since the seal’s dependability is dependent on the flexibility of the seat rubber when the flow is closed. The disk first interacts with the seat at roughly 85° for a 90° revolution in this sort of valve. In low-pressure applications, concentric butterfly valves are commonly employed.
There are various varieties of concentric butterfly valves depending on the connection.
- Wafer type ends.
- Lug type ends.
- Both flanged ends.
- Butt-welded types end.
Concentric butterfly valves have a relatively simpler design. The valve body, seals, flap , and stem are the main components of a concentric butterfly valve. The classic butterfly valve has a disk in the center of the attached pipe and a stem connected to the actuator or handle on the valve’s outside.
When the valve is closed, the disk is parallel to the flow, and the valve seat is closed. The stem is sealed with an O-ring. When the valve turns 90 degrees with the help of an actuator or handle, the disk travels away from the valve seat and is located parallel to the flow. The flow can be throttled or proportionate when rotated at an angle less than 90 degrees.
The Time of Using Concentric Butterfly Valve.
Concentric butterfly valves employ soft sealing material, which can only be used in basic (water & wastewater treatment plant), special liquids (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.
Operation and Maintenance of Concentric Butterfly Valve
- The concentric butterfly valve must be fully open and closed periodically during operation. Otherwise, the valve will rust.
- If the closure is not rigorous during the closing process, the valve should be fully opened again, and the valve should be closed again after flushing the impurities in the inner wall using the pipeline’s hydraulic pressure.
- Filter the impurities in the pipeline as far as possible to prevent the butterfly valve from squeezing out the sealing surface when it closes, resulting in the phenomenon that it cannot be completely closed.
- When the valve is throttling, the back of the valve plate is prone to cavitation, which might harm the valve. In general, the valve is employed in states greater than 15 degrees.
- Prevent mechanical valve damage and deterioration of valve quality caused by erosion of sediments, chemicals, or moist gases in the atmosphere.
- Threads, bearings, and gears should be greased regularly.
The operating mechanism must lock itself when the concentric butterfly valve is in the middle opening.