Diaphragm Valves Manufacturers

The diaphragm valve is equipped with a flexible diaphragm or combined diaphragm in the valve body and the valve cover, and its closing member is a compression device connected with the diaphragm. The valve seat can be either a weir shape or a pipe wall through the flow channel. The advantage of the diaphragm valve is that its operating 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 impacting the working parts of the operating mechanism. In addition, there is no need to use any form of separate seal at the valve stem, unless it is used as a safety device in controlling harmful media. In the diaphragm valve, since the working medium contacts only the diaphragm and the valve body, both of them can use a variety of different materials, so the valve can ideally control a variety of working media, especially for media with chemical corrosion or suspended particles. The operating temperature of diaphragm valve is usually limited by the materials used for diaphragm and valve body lining, and its operating temperature range is about – 50 ~ 175 ℃. The diaphragm valve is simple in structure and consists of three main parts: valve body, diaphragm and valve head assembly. The valve is easy to disassemble and repair quickly, and the replacement of the diaphragm can be completed on site and in a short time.
The structural form of diaphragm valve is very different from that of ordinary valves. It is a new type of valve and a special type of block valve. Its opening and closing part is a diaphragm made of soft material, which separates the inner cavity of the valve body from the inner cavity of the valve cover and the driving parts. It is now widely used in various fields. Common diaphragm valves include rubber lined diaphragm valve, fluorine lined diaphragm valve, unlined diaphragm valve and plastic diaphragm valve. The diaphragm valve is a stop valve that uses the diaphragm as the opening and closing member to close the flow channel, cut off the fluid, and separate the inner cavity of the valve body and the inner cavity of the valve cover. The diaphragm is usually made of elastic, corrosion-resistant and impermeable materials such as rubber and plastic. According to the structure, the diaphragm valve can be divided into six types: Weir type diaphragm valves, DC diaphragm valve, stop diaphragm valve, straight diaphragm valve, gate diaphragm valve and right angle diaphragm valve; The connection form is usually flange connection; According to the driving mode, it can be divided into manual diaphragm valve, electric diaphragm valve and pneumatic diaphragm valve. Among them, pneumatic driving is divided into normally open diaphragm valve, normally closed diaphragm valve and reciprocating diaphragm valve. According to the driving mode, there are manual diaphragm valve, pneumatic diaphragm valve and electric diaphragm valve.Weir type valves have multiple nick names – some of which are saddle valve, block Valves, A type valves and ridge valves, occasionally mistakenly called a pinch valve, however a pinch and diaphragm valve are complete separate entities.
The valve body with corrosion-resistant lining and the corrosion-resistant diaphragm are used to replace the valve core assembly of the diaphragm valve, and the movement of the diaphragm is used to adjust. The valve body of diaphragm valve is made of cast iron, cast steel or cast stainless steel, and lined with various corrosion-resistant or wear-resistant materials, diaphragm material rubber and polytetrafluoroethylene. The lining diaphragm has strong corrosion resistance and is suitable for the regulation of strong corrosive media such as strong acid and alkali.

The diaphragm valve has simple structure, small fluid resistance, and larger flow capacity than other types of valves of the same specification; No leakage, can be used for the adjustment of high viscosity and medium with suspended particles. The diaphragm separates the medium from the upper chamber of the valve stem, so the medium without packing will not leak out. However, due to the limitation of diaphragm and lining materials, the pressure resistance and temperature resistance are poor, which are generally only applicable to 1.6Mpa nominal pressure and below 150 ℃.

The flow characteristic of the diaphragm valve is close to the fast opening characteristic, which is approximately linear before 60% of the stroke, and the flow changes little after 60%. Pneumatic diaphragm valves can also be equipped with feedback signals, limiters, positioners and other devices to meet the needs of automatic control, program control or flow regulation. The feedback signal of pneumatic diaphragm valve adopts non-contact sensing technology. This product uses a thin film propulsion cylinder to replace the piston cylinder, eliminating the disadvantage that the piston ring is easy to be damaged, resulting in leakage and thus unable to push the valve to open and close. When the air source fails, the hand wheel can be operated to open and close the valve.

Diaphragm valve is a special type of block valve. Its opening and closing part is a diaphragm made of soft material, which separates the inner cavity of the valve body from the inner cavity of the valve cover.

Due to the limitations of valve body lining process and diaphragm manufacturing process, it is difficult to manufacture large valve body lining and diaphragm. Therefore, diaphragm valve is not suitable for large pipe diameter, and is generally applied to pipelines ≤ DN200.

Due to the limitation of diaphragm materials, diaphragm valves are suitable for low pressure and low temperature applications. Generally, it should not exceed 180 ℃. Since the diaphragm valve has good anti-corrosion performance, it is generally used in devices and pipelines with corrosive media. Since the service temperature of the diaphragm valve and the applicable medium are limited by the lining material of the diaphragm valve body and the diaphragm material.

Characteristics of diaphragm valve

(1) The fluid resistance is small.

(2) It can be used for medium containing hard suspended solids; Since the medium is only in contact with the valve body and the diaphragm, there is no need for the stuffing box, there is no leakage problem of the stuffing box, and there is no possibility of corrosion to the valve stem.

(3) Suitable for corrosive, viscous and slurry media.

(4) It cannot be used in high pressure situations.