Areas with a potentially explosive atmosphere in industrial plants are defined by the German Ordinance on Industrial Safety and Health and classified into different zones (0/20, 1/21 and 2/22). The purpose of this zoning is to define the type of danger in each case so that corresponding explosion protection measures can be taken. Alongside many organisational measures, the installed plant components, such as valves, must be designed for and comply with the requirements for the relevant zone.
The definition for each Ex zone is based on the type of potentially explosive atmosphere (gas or dust), the probability that it will occur and the duration of its occurrence.
Zones 0, 1 and 2 are for gas/air mixtures and zones 20, 21 and 22 are for dust/air mixtures.
Special precautions must be taken in the local environment (rooms, etc.) and within the plant (pipelines, valves, control units, etc.) depending on the defined zone.
Ex zone 0:
Potentially explosive gas/air mixtures can occur continuously or frequently over a long period of time in this zone.
Ex zone 1:
Potentially explosive gas/air mixtures can occur occasionally in normal operation in this zone.
Ex zone 2:
No potentially explosive gas/air mixtures will normally occur in this zone. However, potentially explosive atmospheres may occur for a short period of time in exceptional cases under certain circumstances in this zone.
Ex zone 20:
Potentially explosive dust/air clouds can occur frequently and for long periods of time in this zone.
Ex zone 21:
Potentially explosive dust/air clouds can occur occasionally under normal circumstances in this zone.
Ex zone 22
Potentially explosive dust/air clouds will not occur under normal conditions. However, they can occur very rarely for a limited period of time in exceptional cases.
Alongside the already mentioned organisational measures, such as employee training and marking of the hazardous areas, special structural measures must be taken in the plant or the rooms to prevent an explosion or to minimise the risk of explosion. This also applies to all the different types of valves that have been installed. The valves may only be installed in a potentially explosive zone if they have been designed or function in compliance with the corresponding ATEX regulation.
The Ex zone does not only cover areas where media that are prone to trigger an explosion due to their composition, such as chemical substances or gases, are processed but also covers areas where a large number of generally harmless media are processed that may nevertheless generate potentially explosive conditions. For example, dusts, vapours or gases could be generated during the transport or processing of these usually harmless substances that could combine with oxygen or air to generate an explosive mixture.
Naturally, pinch valves that are installed in plants that have areas with potentially explosive atmospheres are also subject to the requirements of the ATEX Directive (RL2014/34/EU). Pinch valves from AKO that are installed in these zones are configured to conduct the electrical charge that is generated from friction or other influences safely away and thus prevent any discharge in the form of sparks within the potentially explosive atmosphere.
Pinch valves for Ex zones are equipped with special sleeves that have electrically conductive properties in order to also prevent an explosion inside a pipeline system.
Just like the standard pinch valves, explosion protection pinch valves have a modular design and can be configured – still in compliance with all of the regulations – to the requirements of the plant and the medium. You can select from a broad range of nominal sizes, connection options, housing and connection materials and various qualities of conductive compounds. We would be pleased to advise you on the configuration of the optimum pinch valve for you.
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