Continuous Inkjet printers are used widely throughout manufacturing and packaging industries to apply information, identification codes and best before dates etc. onto products and packaging made from various materials such as glass, card and metal.
This type of printer is extremely versatile and can print, for example, large logos onto cardboard boxes or tiny codes onto electronic components.
Various organic solvents such as Methyl Ethyl Ketone (MEK) are used as carriers for the ink pigment. Anyone who runs one of these printers will know that they can create a noticeable odour especially in an enclosed room and everyone knows that breathing solvent fumes is generally not a good idea.
Many companies are reluctant to install fume extraction systems onto inkjet printers as they would need to cut holes in walls or roofs to vent the fumes outside. They would also have to install expensive and disruptive ducting to carry the fumes away.
Another problem with fixed ducting is that if the inkjet printer moves location then all the ducting needs to be moved as well which again can be expensive and disruptive to production. Also, environmental laws in some countries limit the volume of pollutants which can be released into the atmosphere.
A better alternative is a filtration and recirculation system which extracts air containing solvent vapour from around the inkjet, filters it and then returns clean air to the workplace.
Purex International Ltd were asked to look at this problem by a customer. The problem to solve was that the solvent fumes were not only emanating from the printing head but also from the vent in the printer control unit. This meant that two extraction points would be required.
To solve this problem Purex utilise two specially designed Delta Cowls, one to extract fumes from the print head and the other to extract from the vents on the printer control unit itself. This 2-point approach ensures that fumes are not allowed to pollute the work area.
The delta cowls are attached to 38mm flexible stainless steel arms which are easy to position yet remain in place once installed.
Purex use a specially formulated blend of activated carbon and a chemisorbent media to filter the solvent fumes from the extracted air.
If activated carbon is used on it's own to filter ketone based solvents (like MEK) there is a potential fire risk because a heat producing reaction can take place.
In Purex filters, the chemisorbent material removes the solvent without heat being generated and the pellets onto which the chemical is adsorbed remove the heat from the process. So no fire risk!
Molecules of solvents or other contaminants are adsorbed on to the extended surfaces of the media, form bonds at a molecular level and are then retained within its structure. Clean air is put back into the workplace.
To give you an idea of how much surface area this blended filter media has to adsorb vapour - 1gm has a surface area larger than an Olympic swimming pool !
Good news for maintenance personnel is that Purex filters can be changed in seconds and can usually be changed at the same time as scheduled ink replacement. Thus preventing expensive unplanned downtime.
Various controls and sensors have also been incorporated into Purex systems to deliver extra benefits, for example an ON/OFF control relay automatically starts/stops the extraction unit when the inkjet printer is switched on/off. A run on timer allows the extractor to briefly run on after the inkjet is switched off to ensure all fume is removed.
For more information, visit www.purexltd.co.uk