European Commission 05.07.2018
Dry installed liquid pumps are used in various operating conditions. The range of applications may vary from standard applications without explosion protection measures to applications where a pump´s inlet is connected to a pipe whit permanent explosive atmosphere.
Depending on the ambient atmosphere and the probability of occurrence of explosive atmosphere inside the connected piping, requirements are generated to use an explosionprotected pump.
The manufacturer of the pump is responsible for the category and the intended use of the equipment. The intended use shall consider all operating conditions of the service life including putting into service, starting and stopping as well as putting out of operation. The probability of the occurrence of an explosive atmosphere and the probability of possible ignition sources occurring shall be regarded by the operating company in a risk assessment according to Directive 1999/92/EC.
An important activity is the performance of an analysis (“ATEX analysis”) to check whether the product comes under the scope of application of Directive 2014/34/EU. Pumps without contacts to flammable liquid and without the presence of an ambient explosive atmosphere are not in contact with explosive atmosphere and do not require categories according to Directive 2014/34/EU. Furthermore, what is an acceptable safety value for dry installed pumps? If the occurrence of an explosive atmosphere cannot be avoided, the operating company shall specify the probability of the appearance of a hazardous explosive atmosphere on the basis of the Directive 1999/92/EC. Depending on this probability, the employer has to classify the hazardous areas into zones. For example, in Germany it is regarded as state of the art that the interior of a tank for flammable liquids without inertisation is classified as zone 0 above the liquid level, provided the user does not determine a different zone due to precise knowledge of the product (liquid), e.g. a liquid flashpoint above 55 °C.
The interior of pipes, fittings and plant units, that operationally do not remain permanently filled with liquid, are usually classified as being in the identical zone. For the selection of the category of the explosion-protected equipment (pumps) according to Directive 2014/34/EU, the zone inside the pipe and the zone outside the equipment are significant. In this case, the zone classifications have to be applied to the interior of the connecting flanges. Without detailed knowledge of the safety characteristics of the liquids to be conveyed or without complete classification of hazardous areas zone 0 shall be taken as the basis.
The zones of the pump installation site may vary depending on the construction method of the pipe flanges. To introduce the different explosion protection requirements of equipment, a few examples will be addressed. Depending on the potential of the explosions hazards and the category of the pump as non-electrical equipment, the requirements lead to different conformity assessment procedures for which in some cases a Notified Body must be consulted.
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