The storage of hazardous materials has been defined for decades and is specified in various legal tests such as the Occupational Safety Regulations (BetrSichV) or the Technical Regulations for Flammable Liquids (TRbF). Clearly formulated definitions of active and passive storage exist. However, the solutions implemented in practice often differ from the legal requirements. Standardized solutions are difficult to find, especially for the active storage of smaller quantities in the working space, e.g. a 200 litre drum of flammable liquid.

There are renowned manufacturers of safety cabinets on the market who offer tested products for passive storage of 200 litre drums according to TRbF 20 Annex L or EN 14470-1. However, passive storage presupposes the following requirement:

• Safety cabinets in the sense of this TRbF are used for the storage of flammable liquids in sealed containers within a working space. (Extract from TRbF 20, Annex L – Item 1.1)

But there are extremely few cases in which a 200 litre drum of flammable liquids is stored sealed (= passive) at the workplace. Practice shows that in general active storage exists:

• Active storage is the storage of flammable liquids in mobile containers, which are used in the place in which they are stored as a stationary discharge or collection container or are opened for other purposes. (Extract from TRbF 20 – Item 2.1.6)

So the question remains, what can be used if active storage is required?

The company Düperthal located at the Bavarian Untermain region took up this question and, in collaboration with the experts of the TÜV Süd, developed products which solve these problems. In the first step the focus was on a safety cabinet according to EN 14470-1, which was already approved for passive storage of a 200 litre drum. But how does a passive safety cabinet become a cabinet approved for active storage?

Prevention of the danger of ignition
An important aspect of active storage is continuous earthing in accordance with the TRbF 30 requirements for "filling stations" and the Guidelines of the employer's liability insurance associations BGR 132 "Avoidance of danger of ignition".

This requirement is solved in Düperthal cabinets in that all metal components inside the cabinet, e.g. collection trays and grating are conductively connected with each other. Further, the safety cabinet is equipped with two earthing terminals, one each for the drum and for the drum pump. There are prepared earthing connections on the top of the cabinet which enable the user to connect the system to the earthing and therefore to prevent static charging.

Ventilation and ex-zones
According to TRbF 20, Annex L, safety cabinets for passive storage do not necessarily have to be connected to the ventilation. A substantial reason for this is that closed containers only may be stored in conventional safety cabinets. In the case of active storage on the other hand, critical ex-zones (hazardous area zones) in accordance with TRbF 30 occur due to the open container. As a consequence, the drum cabinet must be ventilated with at least ten-fold air exchange per hour. Further, the ventilation must become active in each cabinet level, which is achieved in a drum cabinet with exhaust and air supply roses in each cabinet level. It is also necessary to monitor the function of the ventilation and to comply with the legal requirements for fans. Düperthal therefore offers a ready to plug in ventilation unit with integrated exhaust monitoring unit which conforms to ATEX.

Pipe penetration
The doors of safety cabinets according to EN 14470-1 or TRbF 20, Annex L, ar self-closing in the event of a fire. But for active storage with drum pumps, this means that the media and energy lines cannot be "simply" passed through the open doors. The ideal solution is a tested and approved pipe penetration for stainless steel pipes. If this pipe penetration is used, up to four stainless steel pipes with a maximum diameter of 20 mm, or optionally one pipe with 28 mm diameter, can be laid so that it emerges out of the side panel or the top of the cabinet. The pipe penetration has been successfully tested in a fire chamber test with the drum cabinet by an independent materials testing institute. The safety cabinet was classified as being Type 90 (= fire resistance for at least 90 minutes). In this way, the optimum solution has been created for connecting an explosion-proof compressed-air drum pump inside the cabinet.

Practical use
GE Global Research Europe is the European research centre of the global company General Electric. The corporation is present in more than one hundred countries and has a clear focus: to transform inventiveness into tangible concepts and products.
Mr. Frey and Mr. Ast of GE Global Research were among the first to use the new Düperthal system tested by the TÜV (German technical inspectorate). Global Research integrated the new solution into its practical processes a year ago – enough time to ask what their experience has been to date:

What are the main tasks of GE Global Research in its Munich location?