Solvent printers and air quality control, part 2
Ventilation/Exhaust: This method usually comes in the form of either running duct work outside of the room, exhausting directly out of the building, or a ceiling hanging filtration unit. It is the most widely recognizable method, although probably the least effective at VOC removal. VOCs are typically heavier than air and therefore hard for moving air to carry around.
All air filtration systems have a capture zone—a radius around the unit—within which contaminants will get sucked into the system and removed from the environment. These systems will have some effect on the overall air quality; unfortunately, very few VOCs will drift into the capture zone and be removed from the environment, thus creating a higher-than-allowable exposure limit environment. These systems can be costly and bothersome to maintain, and the EPA (Environmental Protection Agency) does not want these harmful contaminants exhausted out into the environment. These systems also often require special electrical hookups and building permits for installation—both make this method of VOC removal burdensome. Furthermore, fixed systems can limit your ability to rearrange your shop space or add more equipment as your needs change.
Source Capture System: these systems usually come as a box with hoses that attach directly to the printer and draw off VOCs, thus preventing them from escaping into the room. This proactive method is more effective than exhaust methods, but has several drawbacks as well. While it does keep a large percentage of VOCs from getting into the air, it cannot capture 100% of the VOCs produced by the printer, as VOCs off-gas from many points on the printer. Likewise, as the prints are rolling off of the printer they continue to off-gas, and will continue to off-gas when placed on drying racks.
Once the VOCs are out into the ambient air these systems are not able to remove them. Furthermore, once the printer is shut off, so is the source capture system, so any VOCs not already through the system will escape into the ambient air. In a test of a leading brand of source capture system on a popular brand of solvent based printer conducted by the California State Certified air testing company, the allowable exposure limit was exceeded with in as little as 30 minutes of printer operation, so while it did keep the level in the room considerably lower than with no filtration, it did not seem to be able to remove enough of the VOCs to keep the room below the allowable exposure limits.
Often companies must provide additional ambient air filtration when using a source capture system. Other downsides include expensive consumables and the size and bulk of the unit taking up floor space in the shop, as well as special electrical requirements.
Ambient Air Filtration: these systems are usually free standing units that draw air in through a filtration system and return the clean air back into the room through an exhaust outlet. The key to these units working effectively is that they must have enough air movement to circulate all of the air in the room, thus ensuring all VOCs in the ambient air are given a chance to pass through the filters of the unit. A small device may not move enough air to get all of the VOCs into its filtration system.
The drawback of this system is that it takes up floor space, much like the source capture system; however, in contrast to the source capture system, it can be easily moved around for more fluid movement of product and employees.
Another drawback is that this method is a reactive approach to removing VOCs. 100% of the VOCs get into the air before the device can remove them. However, if an adequately-sized ambient air filtration device is employed properly it can keep the exposure limits in a print room below the allowable limits.
Furthermore, this type of unit can be left running 24 hours a day and will continue to remove all VOCs produced from off-gassing created during drying times. On the ambient air filtration unit tested, the consumable levels were considerably lower than those of the source capture system, and standard 110v electrical power was required. This method has proven to be more effective than either ventilation/exhaust systems or source capture systems alone.
Source Capture & Ambient Air Filtration: this type of system acts as a dual purpose unit, and is the most effective of all the options available. It hooks up to the printer to remove VOCs directly—as with a source capture system—but will also circulate and remove VOCs from the ambient air in the room.
This hybrid device appears to be the best way to keep VOC levels well below the allowable exposure limits. By acting in a proactive manner to remove VOCs directly off of the printer the concentration of VOCs allowed to escape into the ambient air will be considerably lower than if you were just using an ambient air filtration system. And by reactively circulating and cleaning all of the ambient air in the room, any VOCs not removed by the source capture action or caused during off-gassing and drying will be removed in a short time frame, ensuring your shop remains OSHA compliant. Testing by the California State Certified testing company concluded that with this dual purpose air filtration system in place, the VOC levels in the room measured well below allowable exposure limits (see figures 3 and 4).
It is important to recognize that not all printers are able to support a source capture system. While most manufacturers recognize the need to provide exhaust ports on their printers, many printers are still freestanding units with no means of hook-up available. For those systems without pre-existing exhaust ports, utilizing an adequately sized ambient air filtration system would be the most effective method of VOC removal for ensuring OSHA compliance.
There are many factors that will determine the level of filtration required, such as room size, printer type, printer running speed, media size, color gamut utilized, printer running time, built in filtration/ventilation (HVAC), and type of inks used. It is the ultimate responsibility of the shop owner to ensure that adequate VOC removal is provided. The shop owner should be able to rely his or her equipment dealers to acquire the knowledge and expertise to make the best decision on what type of air filtration to install.
Solvent-based printers can be a very effective tool for any sized printing operation to expand the products and services they can offer, and to increase their business success. There are risks associated with solvent printer use, but these risks are not to be feared, they can and should be recognized and neutralized so that operators can function in a healthy and safe environment.
Larry Miller
Vice President
Island Clean Air, Inc.
Solvent printers and air quality control
As the printing world has evolved, so too has the advent of the solvent based wide format printing system. Printing operations of all sizes are recognizing the value of adding these types of printing systems to their production lineups, enabling them to offer new and old customers alike a wider range of printed products. Vehicle wraps and outdoor signage, just to name two, are rapidly expanding market places, and with that comes the continued reliance on the solvent based printers for providing prints that will stand up to the sometimes extreme conditions that mother nature can throw at us. For all those who have hypothesized that the emergence of the UV flatbed printer would displace the need for the solvent based printer, you have underestimated the strength of the solvent based printer. And if sales volumes of current models and the introduction of new brand names are any indication of the strength of the marketplace, solvent printers are here to stay.
It is no secret that shops running solvent based wide format printers experience a level of fumes and odors that can cause health concerns and discomfort for employees and customers alike. Many shop owners describe themselves as having become desensitized to the smells, but often concede that customers entering their store react surprised and respond with “how can you work all day with that smell”? As well, new employees will complain of headaches, dry mouth, and sinus trouble until they eventually become desensitized as well, if not ill to the point of needing medical intervention or simply quitting due to the hostile working environment.
For years it has been accepted that these operating conditions are par for the course and accepted as normal, but we have come to a turning point where these fumes and odors are more than just a nuisance, they pose real health concerns. Whether you are running an eco-solvent printer, a wide format printer (up to 3 meters wide), or a grand format printer (over 3 meters wide) these concerns are dangerously real and present. Therefore, shop owners need to be properly educated as to the effects of exposure to these fumes and odors, as well as preventative measures to provide employees with a safe and healthy working environment. The shop owner needs not only to protect his or her employees’ health, but they need to protect themselves from liability as well.
It is important to note here that just because there is a really bad fume or odor smell in a working environment doesn’t necessarily mean there is a hazardous contaminant present, and that just because you can’t smell something bad doesn’t necessarily mean there is no hazardous contaminant present. While often the two go hand in hand, and the presence of one can indicate presence of the other, a shop owner should not simply assume they are both present or not. Providing a safe and healthy environment is achievable, but before we can address the solutions to reducing or eliminating health concerns caused by overexposure to airborne contaminants, we need to have a better understanding of exactly what the problem is.
The process of solvent based printing is simple: a solvent component mixes with the ink and carries it to the media and is printed onto the same media. The solvent then evaporates off of the media leaving the ink behind to produce a print. This is where the problem begins. The evaporated solvent product has been deemed hazardous for human consumption when found in high concentration levels.
The fumes and odors that you are smelling are called VOCs (Volatile Organic Compounds), and these VOCs are regulated by the government based organization OSHA (Occupational Safety & Health Administration). For many of the compounds found in most solvent printers, exposure limits for humans have been set as low as 20ppm (parts per million). Often information on the allowable exposure limits can be found in the Material Safety Data Sheet of the ink, which should be provided to you by the dealer or manufacturer when you purchase a solvent based printer. The allowable exposure limit of any given chemical is very important for shop owners to know because if an employee becomes ill or suffers health problems as a consequence of overexposure to these VOCs the shop owner can be held liable for medical expenses, workers’ compensation claims, or possibly subject to fines by OSHA for non-compliance.
Understanding VOCs, ppm, and allowable exposure limits is a complicated process involving lengthy mathematical equations, and it is a little much to expect the average shop owner to know all of the particular elements that can come into play. Furthermore, simply knowing what the allowable exposure limit is doesn’t tell us whether a particular shop environment is compliant or not. The human senses can detect that VOCs are present but can not discern the level at which they are present.
To know the level of VOCs that these machines produce, indoor air quality testing must be done. I contacted many of the printer manufacturers directly to ask for data on the level of VOCs produced by their printers, and the typical answer was “there are too many variables to determine what concentration level may or may not be present when our printer is running. It is ultimately the responsibility of the shop owner to ensure that he or she provides a safe and compliant working environment for his or her employees”. As such, the printer manufacturers have been able to wash their hands of any responsibility regarding VOC exposure to the end user. And while the manufacturer may be correct in its declaration, this unfortunately doesn’t help end users establish what they may or may not need to do to provide a clean and healthy working environment for their employees.
In between the manufacturer and the end user lies the dealer, and most quality dealers will take the time to educate the end user about the need for adequate air filtration when employing a solvent based printer, as well as offer them proven and accepted solutions so the end user can make the best possible decision on how to provide his or her employees with the cleanest and safest working environment. These dealers have taken the time and energy to educate themselves on available solutions, and as an end user I recommend that you utilize their knowledge and expertise on this issue. In fact, I believe that a dealer should not be selling a solvent based printer with out offering an air filtration system with it, as well as taking the time to explain to customers why such a system is required.
Having said all of that, it is very impractical and costly for each end user to hire in an indoor air quality testing company to make sure they remain compliant, or to measure whether or not filtration is even required to meet compliance. Realizing this hurdle to end users, Island Clean Air Inc. of Vancouver, BC, contracted an independent California State Certified air testing company to measure the concentration level of some of the most common printers on the market today, and the results were surprising.
Each test was conducted under what was to be considered an average operating environment of a room in size from 100 sqft (10’x10’) to 400 sqft (20’x20’), and the printers were run at average print speeds on full size media with a full gamut of colors. Each printer’s production speed was dependent upon the overall capacities of the individual printer. Tested were the HP Designjet 9000s, Colorspan Gator 72s, Mimaki JV3-160, and the Mimaki JV5-160. Each test was conducted at different locations on different days to avoid any cross contamination and ensure the objectivity of the results.
For the initial testing, no means or air filtration or ventilation was employed, it was simply the printer running in a sealed room. Interestingly, each printer, in its tested room size, surpassed the allowable exposure limit with in 30 minutes of print operation, with a measured range of between 20ppm and 200ppm, depending upon which printer was tested. As production occurred past the 30 minute mark, this number continued to increase (see figure 1 and 2)—remember that the allowable exposure limit can be as low as 20ppm!”
These tests conclusively show that solvent based wide format printers are prone to creating an environment with higher than allowable exposure limits. Therefore, shop owners can conclude that if you are running a wide format solvent based printer, you must provide some method of filtration or ventilation to ensure your employees are not put into a working environment where their health and safety may be at risk. What a shop owner decides to provide for filtration/ventilation is their own prerogative, and is a point of debate amongst air filtration system manufacturers.
Next month we’ll compare 4 available methods of VOC removal and analyze their pros and cons.
Larry Miller
Vice President
Island Clean Air, Inc.
Follow Graphic Arts Magazine
