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 Mink claw vacuum pump |
The complete model range of Mink claw vacuum pumps for pneumatic vacuum conveying is now also being offered by the Maulburg manufacturer Dr.- Ing. K. Busch GmbH in a version which conforms with the ATEX Directive. This means that there are now vacuum generators available for producing 60 to 300 m3/hour for use in potentially explosive atmospheres. Two different versions are available according to the zone classification in which the vacuum pumps will be used.
Whenever an operating company has plans to operate with potentially explosive substances, the first step it must take, according to EU Directive 1999/92/EG (ATEX 137), is a safety analysis and the resulting zone classification of its production facilities. Busch in turn had its vacuum generator assessed according to EU Directive 94/9/EG (ATEX 95) and a guarantee produced that it conforms with the relevant directives in the form of the EU Certificate of Conformity. Co-operation between plant operating companies (ATEX 137) and vacuum pump manufacturers (ATEX 95) has given rise, on the basis of both directives, to a self-contained safety system with which explosions are effectively avoided.
In practice, conveying plants can have the widest range of ATEX-relevant constellations. Busch has standardised its Mink vacuum pumps to conform with ATEX for the most commonly used zone constellations.
1. If there is a potentially explosive atmosphere present inside a plant, either continuously or over longer periods, then the classification must be a Zone 20. Zone 21 is defined in the area around the product separator and the vacuum generator, which means that a potentially explosive atmosphere can occur there from time to time. This occurs, for example, if a cloud of combustible dust can escape from the plant over a valve. One normally assumes classification of the area in the line after the product separator (clean air line) as Zone 22 since fine particles can pass through the separator or can find their way into the clean air line due to a fault on the product separator.
A Mink claw vacuum pump must be used here which conforms with the requirements for Zone 21 outside around the pump and the motor and 22 in the pump.
2. It is much more common with pneumatic conveying systems to find a constellation of the zones where a Zone 20 exists upstream of the product separator and in the line after it, separated from the product separator by a filter, which is defined as Zone 22, but there is no potentially explosive atmosphere around it. What this means for the vacuum generator is that no zone is defined in the immediate surroundings and Zone 22 applies inside. Busch offers a simplified, more favourably priced version, of an ATEX conform Mink claw vacuum pump for such applications.
This clear classification of Mink claw vacuum pumps according to ATEX simplifies selection of a suitable vacuum generator for the plant operating company. It ensures that the specified ATEX directives are observed and that the conveying plant is safe.
Picture captions:
1. Mink claw vacuum pump for Zone 21 in the direct vicinity of the pump and Zone 22 inside the pump
2. Responsibilities according to Directive 94/9/EU and Directive 1999/92/EU
Dr.-Ing. K. Busch GmbH
Marketing/ Marketing Services
28th July 2005