Explosion protection in a printing ink production plant

Paul Boughton

Since its foundation in 1843 by printing press proprietors Friedrich and Christian Jänecke and innkeeper Friedrich Schneemann, Jänecke+Schneemann has grown into one of Germany’s most successful manufacturers of printing ink.

Today its range of products includes offset inks, liquid flexo and rotogravure inks, together with screen printing inks for a huge variety of printing processes and printing substrates. The inks are used in many fields, including flexible packaging such as carrier bags and printed paper articles such as cardboard. Labels and foodstuff packaging are examples of other important markets.

Recently the company outgrew its site in Hanover and moved to Höver on the outskirts of the city. As part of a larger construction project, a 7000m2 production facility for flexo inks has just been completed on this new site (Fig.1). The entire facility is classified as Zone 1 due to the presence of solvents and other potentially hazardous substances.

Consequently, all of the electrical equipment there is explosion protected. This includes everything from switches, circuit-breakers, fluorescent lighting, signal lights, signal horns, control stations and junction boxes right through to operator interface terminals.
R STAHL Schaltgeräte and R STAHL HMI Systems supplied almost all of this equipment, while electrical wiring was carried out by Seelze-based Wahl & Co in close co-operation with TÜV Hanover – the German Technical Inspection Authority.

The production process is subdivided into four zones: delivery and storage of raw materials, dispersion of solvents and colour pigments, intermediate storage and dosing of inks, and container filling.

As the entire production facility is designed to meet the latest safety engineering and environmental regulations, strict compliance is a top priority. This is especially important during solvent delivery and storage.

Liquid raw materials are supplied from underground tanks in the outer area to the plant building. Managed by a central control station (Fig.2), 16 underground tanks, each with a 30m3 capacity, are filled with the raw materials.

The tank supply lines are controlled and monitored by means of an explosion protected Type ET125 operator interface terminal and an 8146 control station.

The safety of operating personnel is ensured by means of a Series8491 explosion protected signal horn, while in the outside area the apparatus shown in Fig.3 ensures that no hazardous situations can occur during delivery. In the event of danger, an 8030 installation switch and Series8537 safety switch ensure swift and safe plant shutdown.

Depending on production demands, raw materials stored in the underground tanks can be distributed throughout the production facility. This is done by means of a distribution panel (Fig.4), via which the various components for different inks are selected. Once selected, these components are transferred to large impeller-type mixers for further processing.

A further process step involves mixing colour pigments and solvents to encourage dispersion. Greater dispersion means finer ink, so this is an important step in terms of product quality. To begin with, the solvent and pigment mixture is pre-dispersed under a dissolver. This preparation then undergoes ultra-fine grinding in a cone mixer mill to achieve maximum dispersion (Fig.5).

The most important ink quality indices, such as degree of dispersion and viscosity, are monitored continuously by the quality management system during the entire production process. If the – known as primary colour inks – are stored temporarily in tanks with a capacity of 2.5tonnes. Transfer of these intermediate products, together with both storage and further distribution, are managed via Series8146 control stations and Type8008 control switches (Fig.6).

The various primary colour inks are removed from these intermediate storage tanks via an automatic weighing and dosing station and are then mixed to form the end product.
After quality inspection, the finished ink is decanted into a whole array of delivery packaging ranging from 10kg cans to 1000kg containers.

The entire production area is illuminated both inside and outside by EXLUX6000 Series explosion protected lighting. Their rugged design and strong materials of construction make this lighting ideal for resisting aggressive media and ensuring safe workflows.

Jänecke+Schneemann's new production facility also complies with the latest environment regulations. To this end, it makes use of a Thermal Regenerative Exhaust System (TRES) that uses combustion to clean solvent-laden air before its discharge into the environment. In return, energy produced during the combustion process is reused in the ink production process.

The next stage in the Höver construction project is due to be implemented over the next five years. This will more than double the size of the facility and put Jänecke + Schneemann in an even better position to compete in the international printing ink market.

Dipl.-Kfm Friedhelm Jänecke is Managing director of Jänecke + Schneemann Druckfarben GmbH, Hanover and Dr Andreas Kaufmann is Product Manager Lighting, R STAHL Schaltgeräte GmbH, Waldenburg.

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