The most difference between plug valve and butterfly valve are following:structure,function in pipe system,stroke of valve etc.The plug valve is a fast-switching, straight-through valve that can also be used for suspended particles due to the wiping action between the rotary sealing surfaces and the complete contact with the flowing medium during full opening.

Another important feature of plug valve is that it is easy to adapt to multi-channel structures, so that one valve can get two, three, or even four different flow paths. This simplifies the piping system design, reduces valve usage, and some of the connection accessories needed in the equipment.

The plug body with a through hole serves as a valve for the opening and closing part. The plug body rotates with the stem to achieve the opening and closing action. Small, non-filled plug valves are also known as "Cock". The plug valve is the earliest type of valve, which has a simple structure, quick switch and low fluid resistance. The ordinary plug valve is sealed by the direct contact between the finished metal plug body,so the sealing performance is poor, the opening and closing force is large, and it is easy to wear, and can usually only be used for low pressure (not higher than 1 MPa) and small.

The butterfly valve is a valve in which a closing part is a disc that rotates around the valve shaft to open and close, and is mainly used for cutting and throttling on the pipeline.

According to the structure the butterfly valve could divide into:

(1) Centerline butterfly valve

(2) Single offset butterfly valve

(3) Double offset butterfly valve

(4) Triple offset butterfly valve

The butterfly valve opening and closing part is a disc-shaped butterfly plate that rotates around its own axis in the valve body to achieve the purpose of opening and closing or adjusting. The butterfly valve is normally less than 90° from full opening to full closing. The butterfly valve and the rod have no self-locking capability. For the positioning of the butterfly plate, a worm gear reducer is added to the valve stem. The use of a worm gear reducer not only enables the disc to have a self-locking capability, but also stops the disc at any position and improves the valve's operating performance.

The butterfly valve belongs to the angular stroke valve, that is, the valve plate of the butterfly valve rotates 90° around the valve shaft to complete the opening and closing action of the butterfly valve. Therefore, the butterfly valve opening height is only one quarter of the diameter of the channel, so the opening and closing is rapid.

The butterfly valve not only has a cut-off effect, but also has an adjustment function. The butterfly valve opens and closes quickly, and can be frequently opened and closed. It is especially suitable for applications requiring quick opening or cutting. In some working conditions with limited installation space, the butterfly valve with clip-on connection can be selected to save space.

Therefore, it can be made into a large diameter, and the butterfly valve above DN300 is used more. It can also be used to transport media in pipes containing small particles that are unclean.