Diaphragm valve: refers to a flexible membrane or combined diaphragm installed in the valve body and bonnet, and the closing part is a compression device connected with the diaphragm. The valve seat can be a weir shape or a straight through type.
(1) Advantages:
① The control mechanism is separated from the medium passage, which not only ensures the purity of the working medium, but also prevents the possibility of the medium in the pipeline from impacting the working parts of the control mechanism. There is no need to adopt any form of separate seal at the valve stem, unless it is controlling harmful media Used as this safety facility;
② Since the working medium is only in contact with the diaphragm and the valve body, both of which can use a variety of different materials, the valve can ideally control a variety of working media, especially suitable for media with chemical corrosion or suspended particles.
③ Simple structure, only composed of three parts: valve body, diaphragm and bonnet assembly. The valve is easy to quickly disassemble and repair, and the replacement of the diaphragm can be completed on site and in a short time.
(2) Disadvantages:
① Due to the valve body lining process and diaphragm manufacturing process and restrictions, larger valve body lining and larger diaphragm manufacturing process are difficult, so the diaphragm is not suitable for larger pipe diameters, generally used in DN≤200mm On the pipeline.
② Due to the limitation of diaphragm material, diaphragm valve is suitable for low pressure and low temperature occasions. Generally, it does not exceed 180°C; ③ The adjustment performance is relatively poor, and it can only be adjusted in a small range (usually it can be used for flow adjustment when it is closed to 2/3 opening).
