Single seat valve

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Single seat valves are used for simple shut-off in hygienic applications, such as B. in the brewery, beverage, milk processing and food industries as well as in the pharmaceutical, healthcare, biotechnology and fine chemical industries. A distinction is made between single-seat shut-off valves and single-seat switchover valves.

Function of a single seat valve

Valves for hygienic applications are usually equipped with an air-spring actuator. The actuator piston rod is connected to the valve disk. A stroke movement of the valve is generated by applying air under the piston surface. When the air admission is deactivated, the valve is closed by the spring force of the actuator.

With the simple shut-off, there is only one seal in the valve disc, which separates the pipes from one another. In the event of a possible seal defect, liquid may leak into the second pipeline. For this reason, single-seat valves are not suitable for separating "hostile" media.

Simple shut-off with just one seal
Changeover valve
Structure of a valve

Structure of a valve

  1. Control and feedback system
  2. Drive: The control air is either connected directly to the drive or to the respective control and feedback system and guided under the piston surface of the drive via the internal air duct. Shut-off valves can be equipped with different types of drive, which have either a spring-opening / air-closing or an air-opening / spring-closing effect.
  3. Lantern: The open lantern separates the drive and product parts. It enables visual inspection of the rod seal and also serves to indicate any leaks. Furthermore, the heat transfer from the valve housing to the drive is prevented.
  4. Valve disk: With the valve disk, a distinction is made between upper and lower valve disk. In the case of single-seat valves, sealing takes place via just one valve disc. In the case of double seat valves, the pipeline is sealed using the valve disk (to seal the lower housing) and an additional, upper valve disk (to seal the upper housing).
  5. Valve housing: The clearance- free housing should ideally match the diameter of the connecting pipeline in terms of its clearance height. This avoids domes and swamps with their negative effects such as oxidation damage or cleaning problems. A flow-optimized spherical shape of the housing offers the best flow profiles without stall .

Application examples

In practical use, single-seat valves are used, for example, as emptying or drainage valves or used to shut off a bypass line. These valve types are often used as metering valves.

Direction of flow

In order to avoid pressure hammers when the valve is closed while the product is flowing, single-seat valves are switched against the direction of flow of the product, if this is technically possible.

See also

Individual evidence

  1. ↑ Wolfgang Kunze: Technology brewers and maltsters. 11th edition, VLB Berlin, 2016, ISBN 978-3-921690-81-9 , p. 458
  2. ↑ Bernd Thier: Industriearmaturen: Bauelemente der Rohrleitungstechnik, 5th edition, Vulkan Verlag, Essen, 1997, p. 516
  3. ↑ EHEDG Guidelines DOC 8: Design criteria for hygienic machines, apparatus and components. 2nd edition, April 2014, p. 11 ff