Packaging printers working with solvent inks must take the danger of explosion into consideration. This blog gives an explanation of the latest regulations in this area and measures that can be taken to assure safe ink logistics.
ATmosphères EXplosives – otherwise known as ATEX – is used as a synonym for two European directives on the danger of explosion in atmospheric circumstances. Work locations where there is a risk of dust explosions have had to comply with legal ATEX directives. The directives also apply to dispensing systems that are used for solvent inks or paints.
The so-called explosive atmospheres can come about because of flammable gases, vapours or fine powder substances. In the printing industry, attention must be paid to solvent vapours. The more volatile the vapour, the easier it burns. When mixed with sufficient oxygen and an ignition source, it forms the perfect recipe for an explosion. Indeed, a spark generated from the turning of a switch is enough to cause an explosion.
Safe working environment
The first European directive covering safe working environments was characterised by 2014/34/EU, better known as ATEX 114. This directive describes the instructions for equipment where there is a present danger of explosions caused by gas or substances. These specific preconditions are described in European and international standards, such as EN-IEC 60079. Equipment that complies with these requirements is tested and authorised to carry an international logo. This logo is recognisable by a symmetrical hexagon that contains the inscription of an Epsilon with an ‘X’. In order to assure workers’ safety at locations where a danger of explosion is present, the second directive, 1999/92/EG, comes into effect. This is better known as ATEX 153. This directive requires employees to work with among others a risk stock-taking and a zoning plan. The latter provides insight into the danger of explosion per zone.
ATEX 153 distinguishes three safety-zone classifications. Zone 0 describes the greatest risk of explosion. This applies when a mixture of flammable materials is present at a specific location for more than 1,000 hours per year – for example, inside a barrel for base components. Zone 1 is a medium level, where a mixture of flammable materials can be present for between 10 and 1,000 hours per year. Zone 2, the lowest level of risk, covers a flammable mixture present for fewer than 10 hours per year – for example in the area surrounding a barrel containing base components. The applicable zone is determined by the employer.
Besides ATEX, there is also the IECEx accreditation. An important difference between ATEX 114 and IECEx concerns the fact that ATEX only applies to Europe and that IECEx aims for world-wide recognition.
The biggest difference, however, is that ATEX is driven by legislation, while IECEx is standards-driven. Compliance with the standards is compulsory for IECEx, but not for ATEX. Furthermore, it is sufficient for ATEX when the manufacturer assembles the modules for type-testing and the production control. IECEx requires a third party to take this responsibility. In practice, this means IECEx is regarded as more stringent than ATEX. This is especially so with respect to notification of information during the certification process and assurance of the quality system at the manufacturing plant. Both ATEX and IECEx use the same standards (among which are EN-IEC 60079), but as far as technical content is concerned, there are hardly any differences. Click here for an article in Narrow WebTech magazine about our introduction of an IECEx-compliant dispensing system at drupa 2016.
Explosion-proof dispensing systems
All our dispensing systems for solvent inks are built with explosion-proof features and the applied materials are resistant to the most commonly used solvent-based substances. The design conforms to international safety standards for dispensing volatile explosive liquids. For example, the control desk of the dispensing station, featuring the dispensing computer and monitor, includes an overpressure system. Furthermore, the keyboard and mouse are explosion-proof.
For the discharge of static electricity, the keyboard and the mouse, as well as the hoses, pumps and barrels, are grounded. Without the need for operator action to achieve grounding, this ‘passive’ grounding ensures that the entire system discharges static electricity.
The electrical control cabinet, the network computer and the printer – or printers – are situated in a separate space that is free from explosive gases and close to the dispensing system.
The dispensing system is also equipped with a grounding clamp, which the operator must fix to the dispense container every time a recipe is dispensed.
Some customers work with plastic inlays in the dispense containers, eliminating the need to wash or discard the dispense buckets after dosing. For these situations we have developed a special grounding module, which grounds both the ink and the (metal) dispense container.
At each dispense container a magnetic clamp is mounted that makes contact with the bucket and is brought by means of a pin in the ink. This magnetic clamp is grounded during each dispensing cycle by fixing the grounding terminal in position.
Furthermore, machines with automatic roller tracks beneath the dispensing head provide an automatic grounding of the dispense container.
For added security, the system can optionally be fitted with grounding switches on the barrels for base components. These switches are connected to an alarm light that flashes whenever a container is not properly grounded.
Dispensing systems supplied to customers in the European Union are equipped with a 114-ATEX approval and the associated CE certificate. If requested, we can also provide the IECEx approval for you.
If you have any questions about our solutions for your ink logistics, do not hesitate to contact us!