Ink dispensers for solvent inks must be designed to avoid the risk of explosion, environmental pollution and corrosion that their volatile ingredients pose. In this blog we reveal the special design features for durable equipment that enables safe, emission-free handling of solvent inks, in compliance with ATEX regulations and IECEx standards.
Solvent inks are both a safety and environmental hazard because they contain highly flammable, aggressive volatile organic compounds (VOCs) that easily evaporate and create an explosive environment.
Ink dispensing systems for solvent inks must be designed to prevent explosions and emissions, while its constituent materials must be resistant to the most commonly used solvent substances.
Why solvent ink dispensers must offer chemical resistance
Solvent inks are more aggressive than water-based or UV-ink sets, so all constituent materials of a solvent ink dispenser must offer greater resistance properties. Chemical corrosion of parts compromises safety as well as having a negative financial impact. Casing and dispensing valves must be made of stainless steel. Plastic parts such as O-rings that come in contact with solvents must be made of material such as EPDM, to prevent swelling.
What makes a solvent ink dispenser ‘explosion-proof’?
In order to be explosion-proof, in accordance with ATEX and IECEx standards, a solvent-based ink dispenser must be designed to eliminate all potential sources of ignition. In the package printing working environment, these are:
- Static discharge
- Electrical sparks
- Hot surfaces
- Gases escaping into the environment due to broken parts
Grounding to prevent static discharge
All dispensing equipment must be grounded or ‘earthed’ to prevent electrostatic discharges that can cause a spark with potentially catastrophic consequences.
There are two types of grounding: passive and active.
Passive grounding
Passive grounding is where grounding is built into the design of the equipment, and requires no action from the operator. In a GSE Colorsat dispenser, the keyboard and its mouse, as well as the hoses, pumps and barrels, are grounded. Hoses, for example, feature a copper mesh to ensure grounding.
Active grounding
Any equipment parts that cannot be made safe by passive grounding must be actively grounded. This is where the operator must take action to ensure grounding. At GSE, we have developed grounding devices for a number of equipment parts to ensure the safety of our Colorsat dispensers.
There are grounding clamps for conducting static electricity from the dispense container – assuring safety whether dispensing directly into the container, or into a plastic inlay that saves washing time. The operator simply applies the clamp to the bucket – there’s nothing more to it! As a safety precaution, dispensing will not occur if the earth clamp is not connected properly.
Also, grounding switches for base component barrels may be connected to an alarm light that flashes whenever a container is not properly grounded.
Overpressure units prevent electrical sparks
Because electrical circuits can generate a spark if they fail, the electrical parts of the solvent ink dispenser must be kept in a sealed environment, isolated from the atmosphere of the factory. A small box-shaped unit called an ‘overpressure system’ ensures the sealed environment’s atmosphere is over-pressurized. A change of pressure indicates that air is escaping, or the unit is not closed – in which case the control unit will shut down all electronics automatically.
We have developed a unique explosion-proof module for label printing situations that is integrated in the overpressurized control console.
Eliminate risk from hot surfaces and escaping gases
Ensure any equipment is kept away from direct sunlight to minimize the risk of heated surfaces. And while a dispenser is built for chemical resistance, it is still important to strictly follow the manufacturer’s recommended maintenance procedures – so any worn parts are identified and replaced before they can cause leakage.
Solvent vapour extraction for emission-free dispensing
A solvent vapour extraction unit is necessary to remove the harmful fumes that result from the evaporation of VOCs in solvent inks. Vapour may be extracted through holes in the dispense head, or from the back plate of the dispense position, depending on the model of dispenser.
Locate electrical equipment in a VOC-free space!
Finally, a safe location is also important. 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.
ATEX and IECEx certifications assure dispenser compliance
Dispensing systems supplied to customers in the European Union should be equipped with a 114-ATEX approval and the associated CE certificate. This is the case with all GSE Colorsat ink dispensers – and if requested, we can also provide the IECEx approval for you.
Overall, a dispenser equipped with passive and active grounding, fully enclosed electronics, chemical resistance and vapour extraction provides the highest possible assurance of safely handling solvent inks in the printing environment.
If you have any questions about our solutions for your ink logistics, do not hesitate to contact us!
