Diaphragm Valves

We offer a wide range of different types of diaphragm valves from Crane (Saunders) and Sisto,
which are particularly suitable for special or demanding media,
e.g. in the pharmaceutical industry, food and beverage technology, water and waste water treatment,
pulp and paper production, electronics production and many more.

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What are Diaphragm Valves?

Diaphagm valves are the all-rounders among valves due to their wide range of applications. They are used to regulate or shut-off fluids (gases, vapour, liquids).

Construction and function:

A diaphragm valve consists of a valve body with a weir or a flat seat and a flexible, internal shut-off diaphragm as well as a valve top with handwheel or pneumatic or electric actuator.

When actuated, the diaphragm moves towards or away from the valve weir or flat seat by deformation and thus controls the flow rate of the medium depending on the direction of movement. During the shut-off process, the diaphragm is pressed against the weir or flat seat, enclosing it completely and thus creating a reliable seal.

The body can be made of different materials depending on the application, including grey cast iron, ductile cast iron, cast steel, gunmetal or stainless steel. In addition, different body coatings are available. The diaphragm itself can also be made of different materials, such as PTFE, EPDM, natural rubber, Viton, etc., to ensure a wide range of applications.

Some of our models are equipped with the unique "chambered and spiral-supported diaphragm" sealing system, which also maximises the service life and pressure application limit of the diaphragm.

Diaphragm valves with weir seat
(Sisto type 16/20, Saunders type A/AFP)

... are the most commonly used variant. They have a characteristic raised weir or weir seat in the centre of the valve body. The diaphragm seals the diaphragm valve on the weir seat. To do this, the diaphragm is only moved a relatively short distance by means of a pressure piece. To fully open the valve, the diaphragm only needs to be deformed slightly, which minimises material wear. Diaphragm valves with a weir seat are particularly suitable for low to medium flow rates.

Diaphragm valves with flat seat
(Sisto type KB, Saunders type KB)

... have a flat valve seat which allows a free, straight passage with minimum obstruction. Due to their flow-optimised body shape with low flow resistance, they are mainly used in applications with high flow rates or for media such as slurries, sludge and viscous liquids.

Advantages::

Valves based on the diaphragm principle score points with their simple design and low dead space. All mechanical parts are located outside the media-wetted space, the operating medium only touches the diaphragm surface. This virtually eliminates deposits and effectively prevents possible cross-contamination.

In addition to being free of dead space, diaphragm valves are also designed and installed to optimise draining in order to enable residue-free removal of the medium. For optimum draining, there are corresponding specifications for the appropriate angle for installation in the pipework. Diaphragm valves are therefore extremely clean, which makes them particularly suitable for applications that require high standards of hygiene.

Furthermore, diaphragm valves have excellent flow control, effective sealing and easy maintenance.

Areas of application:

Due to their special and robust design as well as the numerous valve variants, diaphragm valves are not only universally applicable, but also particularly suitable for heavily contaminated, highly viscous and abrasive media or for applications that require high hygiene standards.

Possible areas of application are, for example pharmaceuticals, hygiene and sterile technology, semiconductor and microchip production, all areas of water treatment such as waste water, waste water, seawater, cooling water and process water as well as ultrapure and pharmaceutical water, sludge, powder and dust, cellulose and paper production/processing, paint and varnish production/processing, mining and mining technology, gemstone, metal and mineral extraction/processing, fertiliser production, gypsum, cement, sulphur and lime extraction, brine technology, sewage treatment plant technology, granulate production, mechanical and plant engineering, automation technology, food and beverage technology.