Butterfly valve classification and characteristics

The butterfly valve is also called iris valve, to put it bluntly, its vital component as the iris south, random spiral. Disc valve disc is a garden disk, tightly around the high pressure gate valve in a shaft rotation, rotation Angle size, is the disc valve opening and closing degree.

Mainly by the valve body, stem, disc plate and seal ring composition. Body cylindrical, short axial length, built-in disc plate. The disc is driven by the stem and can be opened and closed once by a 90° rotation. Change the deflection Angle of the plate, you can control the flow of the medium. The main seal is the seal ring, its material according to the use and medium commonly used butterfly valve has two kinds of butterfly valve and flange butterfly valve. The wafer butterfly valve is connected between the two pipe flanges with a double bolt, flange butterfly valve is a valve with a flange, with bolts on both ends of the valve flange connected to the pipe flange.

Butterfly valve is suitable for furnace, gas, natural gas, liquefied petroleum gas, city gas, hot and cold air, chemical smelting and power generation environmental protection engineering systems to transport a variety of corrosive, non-corrosive fluid medium on the pipeline, used to regulate and cut off the flow of medium.

Butterfly valve refers to the closing part (disc or butterfly plate) for the disc, around the valve shaft rotation to open and close a valve, in the pipeline mainly plays the role of cutting and throttling. Butterfly valve opening and closing part is a disc shaped butterfly plate, in the valve body around its own axis, so as to achieve the purpose of opening and closing or adjustment. Butterfly valve fully open to fully closed is usually less than 90°, butterfly valve and butterfly rod itself has no self-locking ability, in order to butterfly plate positioning, to install a worm gear reducer on the valve stem. The use of worm gear reducer, not only can make the butterfly plate with self-locking ability, so that the butterfly plate stopped in any position, but also can improve the operating performance of the valve.

Butterfly valve opening and the relationship between the flow rate, basically a linear proportional change. If used to control the flow, the flow characteristics and pipe flow resistance is also closely related, such as two pipelines installed valve caliber, form and so on are all the same, and the pipeline loss coefficient is different, the valve flow will be very different.

If the valve is in the state of large throttling range, the back of the valve plate is prone to cavitation, there is the possibility of damage to the valve, generally used outside 15°.

Butterfly valve in the opening, the valve body and the butterfly plate front end of the opening shape to the valve shaft as the center, two sides of the formation of different states, one side of the butterfly plate front end along the direction of water, the other side of the countercurrent water

To move, therefore, one side of the valve body and valve plate to form a nozzle shaped opening, the other side of the similar throttling hole shaped opening, nozzle side than the throttling side of the flow rate is much faster, and the throttling side of the valve will produce negative pressure, often appear rubber seals fall off.

Butterfly valve operation torque, due to the opening and valve opening and closing direction of different values are different, horizontal butterfly valve, especially large diameter valve, due to the water depth, the torque generated by the valve shaft, the water head difference can not be ignored. In addition, when the elbow is installed on the inlet side of the valve, the deflection will be formed and the torque will increase. When the valve is in the middle of the opening, the operating mechanism needs to be self-locked due to the water flow moment.