Butterfly Valve designes for control, open and closing of fluid. Butterfly valves due to light weight, compact size, high efficiency and low price compared to other types of valves are so popular
This valve has a circular disk that is connected from the top to the shaft and from the bottom attach with a heel to the body. So disc can be moved around the heel and cut off the flow or pass it.
Butterfly valve in different shapes and different sizes are available. Butterfly valve without flange calls wafer type. large butterfly valves can uses with gear , electric actuators, pneumatic or hydraulic done.
The main parts of the valve are: body. usually connected to the pipe by flanges and bolts and to prevent leakage between valve flange and pipe, sealing gasket is set. Disc, depending on type of valve opening is from 15 to 70 degrees, shaft , seat and profile sealing ring.
Types of butterfly valves
Butterfly valve has two kinds of metal and rubber Seat, butterfly valve is generally divided into three groups: Flange, Wafer and Lug Type
Terms and exploit the butterfly valves
When using butterfly valves to control the flow of cavitation conditions had to be careful. Also, if you close the valve too fast, water hammer phenomenon can occur in the system. Cavitation is the result of a difference of pressure on both sides and we must recognize that in the absence of the network downstream of the pressure difference between the valve from the piping system downstream. The cavitation effect of reducing the amount of flow and flow coefficient. In addition to this, cavitation caused a sharp decline in life expectancy will be lower and even plumbing.
One of the most important issues in large size butterfly valves is, the low pressure drop created by the valve in fully open mode. The pressure drop in the fully open position is so small compared to the pressure drop in the pipe network, is often ignored.
Advantages and disadvantages of butterfly valves:
• light weight, compact size, high efficiency and low price
• The low cost maintenance due to lack of movable parts
• made easy In the large sizes
• Low pressure drop
• Disc moving is under the influence of fluid turbulence