Plunger Solvent Dispenser Reduces Emissions and Solvent Use
The largest amount of solvent or related chemicals used normally occurs during clean-up of the print stations.
When chambers and anilox rolls are cleaned manually, not only is more water/solvent used, but also hand cleaning using shop towels is required. These towels must be sent out for cleaning or disposed. Automated cleaning chambers can increase press utilization rates by 25 percent. This allows more product to be printed in the same time period.
Best Management Practices & Pollution Prevention
Automated Roll Cleaning with Alkaline Cleaner
Alternative, less hazardous, cleaning products are available and work well. For example, many low or no VOC products that are lactate based (soy and corn derivatives) work well to cut ink. Additionally, caustic cleaners (high pH) may be a good alternative to high VOC emitting products.
Particle blast cleaning systems that emit no VOC's, using plastic beads or fine particles such as CO2 or baking soda are useful for cleaning press parts.
For enclosed doctor blade chambers, less solvent can be used to wash down the ink fountains and rolls. Only the chamber must be hand wiped, but this part is much smaller than the ink pan and requires very little solvent to be completely cleaned. Only the anilox roll needs to be cleaned on-press. The remaining parts, including the chamber system can be placed in an appropriate washtub. It is a more efficient cleaning system and uses considerably less cleaning solvents or caustic water solutions. This results in a reduction of hazardous waste from cleaning operations and reduced emissions from cleaning solvents. For the press operator, this also allows for faster and less difficult cleanings between print jobs.
Some doctor blade systems are automated for wash-up while the doctor blade remains in the printing position. Automated cleaning systems can further reduce waste in several ways. Most systems utilize a first stage recirculation wash mode where used dirty water/solvent is used to do the initial cleaning. This dirty water/solvent is returned to a common tank after each wash and can be reused many times. If done properly, this first stage wash actually can do most of the cleaning. Clean water/solvent is used for a final rinse only.
It is almost impossible to manage these waste streams manually; so wash ups are typically done with clean water or a reclaimed solvent, all of which goes into waste. When chambers and anilox rolls are cleaned manually, not only is more water/solvent used, but hand cleaning using shop towels is required. These towels must be sent out for cleaning or disposed. Automated cleaning chambers can increase press utilization rates by 25 percent. This allows more product to be printed in the same time period.
For access to vendors who may supply alternative materials and equipment, see the PNEAC Vendor Directory.
The towels used for manual cleaning must be sent out for cleaning or disposed according to state and federal shop towel management requirements. Disposable shop towels may be considered a hazardous waste if they contain solvents.
VOC's and HAP's may be emitted from the cleaning products being used. Which must be considered when evaluating air permitting issues. In addition, some of the solvents may be classified as Section 313 (TRI) reportable. Records must be maintained to determine if reportable quantities are used or stored within the calendar year.
If using water based inks, water containing ink and cleaning compounds are generated during the process of cleaning press. The wastewater may be restricted from discharging into the sanitary sewer depending on the type of inks and cleaning products used. Depending on the pigments in the waste, which may contain regulated metals, the waste may be classified as hazardous. The regulated metals differ among each state.
If using solvent, UV or EB curable inks wastes containing ink and cleaning solvent are generated during the process of cleaning the ink metering system's parts. The waste may be considered a hazardous waste due to flash point, F-listed solvents, or pigments, which may contain regulated metals. The regulated metals differ among each state.
Health & Safety
In order to reduce the risk of injury due to moving parts, the press should be shut down avoid physical injury.
Press operators should wear appropriate safety glasses, gloves, aprons, etc. in order to avoid injury from cleaning chemicals and/or inks while cleaning.
Appropriate equipment should be provided to press operators to transport heavy press parts, such as rollers, etc. when removed for cleaning the press.
Fire extinguishing systems, particularly in solvent based printing presses, should be in proper working order.
Press operators should be carefully trained/informed about fire safety and evacuation procedures, as the press area is a common area to encounter fire.
Press operators should be provided spark proof tools and supplies, particularly at solvent based printing operations.
Press operators should be informed about the hazards associated with the inks and cleaning chemicals used in the press area and how to protect themselves from exposure and injury.