What butterfly valve does the water supply system use?

What butterfly valves are used in water supply system and what are the requirements for using butterfly valves?
 

1. The maximum flow velocity of water at the butterfly valve inlet should not be greater than 3m/s to 5m/s.

 

2. Butterfly valve should be double eccentric soft sealing structure.When fully open, the butterfly plate should be parallel to the direction of flow.

 

3. The butterfly valve should be equipped with a positioning mechanism with adjustable opening and closing positions of the butterfly plate. The positioning mechanism should be able to withstand the impact of two times the maximum torque.

 

4. The allowable stress of the bearing material should be one fifth of the strength limit.

 
Test Method for Opening and Closing Cycle Number of Butterfly Valve in Water Supply System:
 

1. The test medium is clean water at room temperature;

 
b) No matter how butterfly valve is operated, its operating device shall be tested with the valve.The manual operation butterfly valve is driven by handwheel directly or by gear box. The handwheel of butterfly valve or worm deceleration mechanism is driven by driving mechanism of life testing machine.The butterfly valve driven by electric, hydraulic, pneumatic or other driving devices is tested.
 

3. The opening of the valve should reach more than 90% of the actual opening from the starting point of keeping the sealing position completely closed.

 
d) From the opening position to the closing process, the medium pressure in the valve chamber should be 90%-100% of the nominal pressure of the butterfly valve;After reaching the closed position, the outlet side of the butterfly valve should release the medium pressure.
 
e) The butterfly valve shall be closed with the specified torque or maximum operating force of 7.11;
 
f) Sealing performance and operating moment are checked once every 1/5 full number of open and close cycles.After the sealing performance is qualified, the test shall be continued, and the test shall start from zero when the sealing performance is not qualified.
 
g) The number of start-up and shut-down cycles shall be specified in the table. The number of tests shall be recorded by an electromagnetic counter through a travel switch signal driven by a life test machine or an electric, hydraulic, pneumatic or other linkage device.