By Cassandra Balentine
Controlling humidity is an important consideration for print providers. Proper humidification levels alleviate a variety of issues in the pressroom, including electrostatic discharge (ESD) and paper curl, while contributing to a healthy work environment and improving printer function.
Ideally, digital print environments should maintain a relative humidity level (RH) of at least 35 to 40 percent, and a range of humidification equipment is available to manage these levels.
Maintaining proper and consistent humidity in press environments is essential to machine and substrate performance.
There are many disadvantages that come from a print environment with low humidity, including ESD, paper curls, web breaks, and printer downtime. “Maintaining the correct humidity in the production plant eliminates ESD, duct, extends the life of the printheads, enhances quality, and most importantly provides employees with a comfortable working environment, which can increase productivity,” explains Ido Goldstein, chief humidity engineer, Smart Fog.
Proper humidification is required for paper passage and ink separation as well as circuitry operation. “ESD can harm circuitry and prevent correct printer operation,” cautions Scott W. Morgan, president, Humidifirst Co.
Generally, the ESD is controlled with room-monitored 35 to 40 RH levels. He suggests that higher humidity levels may be required for particular equipment or operations. “In such cases, spot humidification is helpful,” adds Morgan.
“Each process requires a specific range of humidity to produce optimum results. The ideal level of relative humidity is between 50 and 60,” suggests Goldstein. He says the minimum relatively for all printers is 35 to 40 percent. “Maintaining the correct level of humidity dramatically extends the life of the printhead and maintains the quality of the paper. The optimum RH for enhancing comfort and suppressing dust is 60 percent.”
DriStreem, a humidification system provider, states that humidifying printing facilities significantly improves print production processes. RH affects the moisture content of hygroscopic materials, such as paper. “Paper absorbs or releases moisture until an equilibrium moisture content is reached, which may affect many of the properties critical for production,” the company explains on its website.
According to another humidification vendor, Condair, paper is a natural material and susceptible to changes in RH. The company’s website explains that if the atmosphere around printing presses and paper storage areas becomes dry, the paper’s exposed edges suffer dimensional change, causing curling. Additionally, tight edges on reels can lead to web breaks and increase machine downtime. Further, a low humidity also increases static build-up, which could cause paper to stick together and not feed or stack correctly.
There are two main types of humidification systems, wetting and non wetting. Additionally, humidifiers come in a range of sizes. Several factors should be considered when looking into humidification, but it is always recommended to seek the advice of a humidification expert.
The first consideration for print providers is the size of the humidifier. “This depends upon supply from outside air into the room, either from an HVAC system, infiltration, or negative pressure from exhaust fans. Second, the size and shape of the room determines the method of humidifying—wall mount, free standing, central HVAC. Look to ceiling height and free space in front of a humidifier for proper placement. Also, determine whether safety overflow precautions require a drain, an alarm, or a water line shut off feature,” recommends Morgan
“You should consult with an experienced humidification expert to size a humidifier and recommend the right equipment for your particular application,” suggests Morgan. He says most humidifier companies have experienced sales representatives or factory-trained experts to assist with the selection.
“Generally you will require less humidity than you think is needed. Therefore, request humidifiers that are self-contained and do not have to be manufactured to a specific output size. Then if more humidification is needed, simply add another and often smaller humidifier instead of re-designing an entire large system. Always remember that room humidification is superior to central humidifiers placed inside ductwork. It is easier to install less expensive and considerably more accurate. Finally, we have found many print rooms where a small ultrasonic humidifier placed next to or above a digital printer has met printer manufacturer warranty requirements without incurring the expense of humidifying the entire room,” shares Morgan.
On the Market
A variety of humidification systems target printing environments.
AMCO direct spray high-pressure humidification systems control a plant’s RH levels. Paper receives and loses moisture readily as the surrounding humidity changes. According to the company, moisture content of five to seven percent provides suitable strength and workability. To achieve this moisture content, a RH of 40 to 50 percent must be maintained.
Condair offers industrial and commercial humidification for many applications, including humidification and humidity control in printing. Condair humidifiers and evaporative cooling systems have been helping improve productivity, sustainability, and health in commercial and industrial applications worldwide for over 60 years. Throughout various industries, the correct level of humidity is of such significant importance that it becomes an essential success factor for manufacturing productivity. For example, due to electrostatic charging, efficient handling of paper in the printing industry depends heavily on an appropriate level of air humidity. Moreover, various production procedures in the pharmaceutical industry are only conceivable if the correct humidity is ensured. Wasted heat from machines and procedural processes is neutralized through evaporative cooling.
DriStreem humidification systems are designed to maintain a consistent RH for print processes, assuring better quality and increased productivity while minimizing costs for machinery downtime and wasted materials.
Among its products, DriSteem offers high-pressure systems that provide evaporative cooling and humidification in multiple zones and a variety of applications. It enables humidification to enhance indoor air quality, manufacturing processes, material longevity, and comfort, while taking advantage of free cooling and energy savings inherent with the technology. The DriSteem high-pressure system handles every aspect of the application from the potable supply water source to the cooled/humidified conditions in the air handler, duct, or space.
FINESTFOG points out that there is an exchange of humidity in paper and the surrounding air, meaning that humidity is gained when the air is too wet or lost when the air is too dry. FINESTFOG air humidification reduces waste and machine downtime while keeping the air humidity at a constant level target. Additionally, it offers an adiabatic cooling effect for the air in the work shop. FINESTFOG air humidification is supplied by FINESTFOG water treatment with pure water, which is at the same time used as process water for the printing machines.
GoFog says its printing humidification systems allow machines to work at higher speeds with less rejection, optimum ink transfer, and improved sheet separation. The GoFog System is custom designed and is easy to maintain. The many benefits of the GoFog printing humidification systems eliminate issues with static electricity that cause costly downtime and product losses, provides paper stability and flexibility by maintaining proper moisture content, increased productivity at high speeds while decreasing rejects, paper warping and curling issues are eliminated, improved ink transfer and sheet separation, and evaporative cooling effect reduces the cooling load and improves employee comfort.
Humidifirst specializes in ultrasonic humidifiers. According to Morgan these are energy efficient, precision humidifiers that are simple to set up and operate. “Most print rooms will either use a wall-mounted misting humidifier, like our Mist Pac series, or if mist is objectionable, we offer a mist-less humidifier that can be loaded near equipment without risk of wetting,” he shares.
Hydrofogger offers humidifiers designed for commercial and industrial use for a range of applications, including commercial printing.
MeeFog helps print providers eliminate the humidification variable while meeting stringent indoor air quality requirements by introducing closely monitored humidity into printing facilities. According to the company, maintaining proper humidity levels in paper warehouses and press rooms ensures dimensional stability for proper registration and optimum ink transfer conditions for improved repeatability and higher production speeds. Facility mangers look to MeeFog to provide high-quality pumps and highly efficient nozzles for optimum performance and longevity. Systems do not require compressed air or steam.
Nortec humidifiers are used by printers around the world to prevent dimensional changes to paper, avoid electrostatic issues, and prevent web breaks and machinery downtime.
Some of the world’s largest printing companies, print machinery manufacturers, and brands put their trust in Nortec humidification systems to help them improve productivity and maintain product quality.
Among its products is the All Nortec ML Series humidification. Modules can be combined in one or more rooms or halls depending on space, room configuration, type of production, and similar factors.
PriscoTech humidification systems improve the working environment, productivity, and press utilization along with product quality. Prisco’s modular concept consists of several different misting head options, which are combined with a high-pressure water pump and ICC controller for almost unlimited configuration possibilities. Water is atomized into micro-sized particles that are absorbed quickly into the air, insuring the ultimate in humidity control. The systems are designed for ease of installation and resistant to dust or dirt. PriscoTech modular humidification systems direct the positive effects of humidity control where it’s needed most, including the pressroom, the bindery, paper storage, and even prepress.
Smart Fog offers non-wetting humidification systems, which include the company’s de-correlation technology and energy and maintenance intensive steam systems. “Smart Fog builds reliable, non-wetting commercial humidifiers made in the U.S. Precision, non-fluctuating humidity, low maintenance, easy, and low-cost installation are just some of the core features,” says Goldstein. Smart Fog employs the latest in antimicrobial technology to help create a safe and clean environment, he adds.
“Smart Fog systems are entirely non-wetting and provide precise non-fluctuating humidity while maintaining moisture-free surfaces. This is essential for printing, as water can damage the expensive printing equipment,” says Goldstein. Smart Fog systems feature easy, centralized installation. The system does not require scattered installation, which can save factory installation and does not require a precise location to generate exact, uniform humidity.
Maintaining the best environment fosters better productivity for a print provider. Humidification systems allow control over RH levels, ensuring a proper printing setting to reduce challenges and improve production capabilities.
Feb2018, DPS Magazine