KST – KROMSCHRÖDER SYSTEM TECHNOLOGY
5.2.2.3.1 General
Automatic shut-off valves shall be in accordance with the following subclauses of EN 161:2007:1)
- for general requirements: subclause 7.1,
- for leak tightness: subclauses 7.2 and 7.3,
- for durability: subclause 7.8,
- for the closing function: subclause 7.9,
- for the closing force: subclause 7.10,
- for the closing time: subclause 7.12,
- for the sealing force: subclause 7.13.
The automatic shut-off valve shall endure the intended cyclings in the IThE.
Valves construction and materials shall be suitable for the used gas composition.
Automatic shut-off valve shall be capable of withstanding back pressure and differential pressure under all process circumstances.
Low cycling applications intended to operate continuously for periods longer than 1 year shall have a redundant safety shut-off system at least comparable with the flow sheet given in Figure C.5 that allows testing the effective closure of the valves at least once a year.2)
High cycling applications (e.g. over 10 000 cycles/year, e.g. pulse firing, …) shall use only valves that are specified capable of an increased number of cycles.3) The instruction handbook shall specify the need to check valves for correct operation, the procedure to be adopted and the intervals at which this should be carried out.
The following chapters are printed with the permission of the DIN Deutsches Institut für Normung e.V. (German Institute for Standardization). For the implementation of the DIN Standard, the version with the most recent issue date is deemed authoritative. This is available from Beuth Verlag GmbH, Burggrafenstrasse 6, 10787 Berlin, Germany.
Our note on this Standard:
1) We recommend the use of type-tested valves to EN 161:2007 so as to ensure the required level of safety. Having passed the type-examination, the requirements are considered to have been proven.
2) Systems operated for longer than one year without interruption must have a redundant structure. Safe closing of the valves can be checked with a tightness control.
3) The maximum number of operating cycles and operating cycle frequency which can be implemented is influenced, if applicable, by the requirements of a SIL/PL level ()
