Ball valve and butterfly valve are more commonly used valves.Some situations can be general, and some conditions can only use one of them.
The difference between the ball valve and butterfly valve is that the opening and closing parts of the butterfly valve is a plate, and the ball valve is a ball, the butterfly valve disc and the ball valve spool are around their own axis for rotation;The disc of gate valve moves up and down along the axis;Butterfly valves and gate valves can be opened to adjust the flow;Ball valves do not facilitate this.
Butterfly valve is characterized by fast opening and closing speed, simple structure, low cost, but the tightness and pressure capacity is not good.The characteristics of ball valves are similar to gate valves, but due to the volume and open and close resistance, it is difficult to achieve large diameter.
Butterfly valve structure principle is particularly suitable for the manufacture of large diameter valve butterfly valve plate installed in the direction of the diameter of the pipeline.In the cylindrical channel of the butterfly valve body, disc disc rotates around the axis, rotation Angle is between 0°~90°, rotation to 90°, the valve brand is fully open state.It has simple structure, low cost and wide adjustable range.Ball valves are usually suitable for liquid and gas without granular impurities, with small fluid pressure loss, good sealing performance and high cost.Comparatively speaking, ball valve seal is better than butterfly valve.Ball valve sealing is by the seat of long-term extrusion on the sphere, it must wear faster than half ball valve, ball valve sealing usually use flexible materials, emergency cut off valve is difficult to use in high temperature and high pressure pipeline.Butterfly valve sealing with rubber as the intermediary, it compared with half ball valve, ball valve, gate valve metal hard sealing performance is far from.Half ball valve after long-term use, the seat also produces traces of wear, it will continue to be used, by adjusting the stem and packing in the process of opening and closing valve stem just rotate 90 °, there were signs of leak, compression packing gland bolts again little, packing can be realized without leakage, while the other is still the small leak valve force, big leaks in the valve.
Ball valve in the opening and closing process is operated under the holding force of both ends of the valve seat, it is larger than the half ball valve opening and closing torque, the greater the nominal diameter of the opening and closing torque difference is more obvious, butterfly valve opening and closing is to overcome the deformation of rubber to achieve, the greater the torque.And gate valve, globe valve operation time is long and laborious.
Ball valves and plug valves are of the same type as a valve, only its closing part is a ball, ball rotating around the center line of the body to open, close a valve.The ball valve in the pipeline is mainly used to cut off, distribution and change the flow direction of the medium.