Pneumatic butterfly valve installation requirements and matters needing attention
Installation requirements of pneumatic butterfly valve:
1, the installation of pneumatic butterfly valve to pay attention to the direction of media fluid and arrow
2, pneumatic butterfly valve open stem valve can not be geographical device, to prevent stem corrosion, there is a cover in the trench, the valve should be installed and maintenance and inspection and operation
3, pneumatic butterfly valve in the horizontal pipeline installation, the valve stem to vertical upward, or tilt a certain Angle, the valve stem is not allowed to be installed down
4, flange and thread connection of the valve, the valve should be closed during the installation. Install flanged valves to ensure that both ends of the flanges are parallel and concentric.
Matters needing attention:
1, the relationship between the opening of the pneumatic butterfly valve and the flow rate, basically changes in a linear proportion. If used to control the flow, its flow characteristics and piping flow resistance is also closely related, such as the two pipelines installed valve caliber, form, etc. are all the same, and the pipeline loss coefficient is different, the valve flow difference will be very big.
2. If the valve is in a state with a large throttling range, cavitation is likely to occur on the back side of the valve plate and the valve may be damaged. Generally, the valve is used outside 15°.
3, pneumatic butterfly valve in the opening, the valve body and disc front of mouth shape to valve shaft as the center, on both sides of the form a complete different state, the butterfly plate on one side of the front end of downstream water direction, the other side of the upstream water direction, therefore, on one side of the valve body and valve plate form like opening nozzle shape, on the other side is similar to throttle aperture openings, nozzle side of more quickly than the throttling lateral velocity, and the side of the throttle valve will produce negative pressure, under the rubber seals often can appear fall off.
4, pneumatic butterfly valve operating torque, due to the opening and valve opening and closing direction of different values, horizontal pneumatic butterfly valve, especially large diameter valve, due to water depth, valve shaft, launching head difference produced by the torque can not be ignored. In addition, valve inlet side device elbow, the formation of deflection, torque will increase. When valve is in middle opening