THE PRINTERS’ GUIDE TO AIR & WATERThe importance of water for paper,printing and packaging

Humidification and Evaporative Cooling

The processing of paper, cardboard, foil,labels and other materials is absolutelydependent on the delicate interplay of awide range of parameters. Paper andother organic materials responddynamically to their immediateenvironmental conditions. More than inany other industry, the three elementsof water, air and heat decide whether ornot the production process runssmoothly and achieves the desired levelof quality.

The right waterFor offset printing, the mostwidespread technique used for printingnewspapers, books and packaging,water is a factor that determinesquality. Minerals such as calcium andmagnesium in particular can causemajor problems. Untreated water isunsuitable for use as process water forproducing fountain solutions.

The capital outlay for a professionalwater treatment system is recoupedrelatively quickly, thanks to process toolcost savings and especially as a resultof the standardisation of the offsetprinting process. In some cases, thewater treated for use in ahumidification plant can also offer thebenefit of being usable for fountainsolution production.

Optimal humidityWhen working with hygroscopicmaterials (i.e. those capable ofabsorbing moisture), humidity must bekept uniformly constant. In mostproduction processes in the printingand post-press industry, a relativehumidity of 50–60% is ideal with roomtemperatures of 20–22°C.

Air that is too dry will cause materialchanges, the buildup of electrostaticcharge, increased dust bonding and

health risks affecting the mucousmembranes, eyes and skin. A controlledindoor climate with optimal humidityensures quality, higher productionspeeds and fewer process disruptions.

Low-cost coolingIn many factory buildings significantthermal loads due to waste heat frommachinery require additional cooling inorder to keep working conditionsbearable for employees. In addition,humidity is relative and thereforedepends directly on room temperature:the higher the temperature, the lowerthe relative humidity.

The energy costs for cooling an entireproduction building can be enormous.By utilising the principle of evaporativecooling, a direct room humidificationsystem can significantly cut the costsof air conditioning.

For many years, the printing industry has been characterised by price wars andover capacities. Cost effectiveness is therefore more important than ever as ameans of ensuring competitive strength. Optimising production, processes andoperating conditions together with modern building technology are the keys tosuccess. And water plays its part as a factor of production: for plant, personneland process materials!

WATER AS A FACTOR OF PRODUCTION

The three elements: water, air and heat

FOR MORE EFFICIENCY

QualityCost

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Issues we can help you with

TYPICAL PROBLEMS

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Boosting quality – cutting costs

An Ideal relative humidity of 50–60% and standardised processwater guard against productionproblems and fluctuations inquality.

WATER AS A FACTOR OF PRODUCTION

iAs a factor of production, water affects quality, costs and time both in theprinting and post-press processes. Yet the actual cause of problems inproduction is not always immediately obvious. The table below offers asummary of typical problems experienced in the areas of paper handling andpost-press work.

How water can help Air Process Cooling humidity water

l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l

Water as a factor of production

1 Three aspects of cost effectiveness

2 The right water for good print quality

3 Optimal humidity protects the paper

4 Cooling through humidification

5 Flatness in sheet-fed offset

6 Constant humidity for web-fed offset

Issue

Setoff

Roller glazing

Doubling

Electrostatic

Emulsification

Creasing

Registerdifferences

Toning

Drying delay

Definition

Transfer of the fresh printing ink to the back of thefollowing sheet in the output stack on the printingmachine.

Ink roller does not accept printing ink.

Double outline of elements of the printed image onthe following sheet, due to mismatched transfer ofthe ink transferred from the previously printed sheetonto the blanket.

Sticking of materials together due to static electricity.

Excessive absorption of fountain solutions byprinting ink in offset printing.

Excessive deformation of the paper when passingthrough the printing machine as a web or sheet.

The individually printed inks are not transferred tothe paper’s surface to achieve 100% matchingcoverage, which causes blurring of the printed image.

Printing of an extra, unwanted visible colour toneover the entire sheet.

Retardation to the printing ink drying process in thestack with sheet- or web-fed offset.

Potential causes

• Build-up of static charge on the paper• Wavy edges or paper under tension• Emulsified printing ink

• Water hardness too high

• Lack of paper flatness• Major differences between temperature and humidity in the press room and paper stack

• Indoor climate too dry• Materials/printing stock too dry

• Proportion of fountain solution too high inthe printing ink

• pH value too low

• Lack of paper flatness• Wavy or tight edges

• Dimensional changes in the paper• Wavy or tight edges• Static electricity

• pH value is suboptimal

• pH value is suboptimal

Paper and cardboard printing stock isprimarily composed of fibres of plantorigin, which is hygroscopic. Materialscan gain or lose moisture from and tothe air. The degree to which this occursdepends on the material’s equilibriummoisture content, the relative humidityand the ambient air temperature.

Equilibrium moisture contentHygroscopic materials seek to bringtheir absolute moisture content intoequilibrium with the ambient air intheir environment. This equilibriummoisture content is then achieved oncethe paper neither gains nor losesmoisture to the room atmosphere.

Depending on the materials fromwhich it is made, the absolute humidityof the paper (4–9%) is typically in astate of equilibrium with a relativehumidity of 50– 60%. If differencesbetween the paper’s equilibrium

moisture content and the relativehumidity are too large, then the paperwill experience changes due to itgaining or losing moisture – causingthe paper’s fibres to expand or shrink.

Relative humidityWhen assessing room climate, theinterplay of the physical quantities oftemperature, absolute humidity andrelative humidity must be taken intoaccount: The quantity of water the aircan absorb in the form of water vapourdepends on the temperature.

Warm air can absorb more moisturethan cold air. When no more watervapour can be absorbed, the air is said

to be “saturated”, and relative humidityis 100%. The relative humidity is theratio of absolute humidity (moisturecontent) and the maximum possiblemoisture content for the air at thesame temperature. If the temperaturerises with absolute humidity constant,then relative humidity falls. Forpractical purposes, relative humidity isthe most important metric forassessing the room climate, as it isrelative humidity that causesdimensional changes in paper and card.

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absolute humidity in g/m3 air rel. humidity = x 100 (%)

max. absolute humidity in g/m3 air

Incorrect handling and a failure to keep humidity constant have seriousconsequences for the flatness of paper and cardboard. As dynamic materials, they are very quick to respond to deviations in equilibrium moisture content.

The trouble-free handling of these materials in the printing machine – theirprintability or “runnability” – are greatly influenced by the humidity.

FLATNESS AND HUMIDITY

Paper is dynamic

THE CAUSES OF DIMENSIONAL CHANGES

Pape

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Relative humidity (%)low high

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Tight edgesTight edges is a paper problem thatalways occurs if a paper stack withnormal moisture content is exposed toambient air that is too dry. Sincerelative humidity is too low, the edgesof the sheet lose moisture, shrinking inrelation to the middle of the sheet. Thepaper’s edges and corners tighten,causing the sheet to become concave.The tight edges problem typicallyoccurs in cold weather.

Wavy edgesSheets of paper start to develop wavyedges when the paper’s moisturecontent is less than the humidity of theambient air. The edges of the sheetsbegin to absorb moisture, causing thepaper to elongate at the edges whilethe middle of the sheet remainsunchanged. Wavy edges are thereforethe result of exposing paper that is toodry to a higher humidity or paper witha normal equilibrium moisture contentto room air that is excessively humid.

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Typically, there is virtually no risk oftight or wavy edges occurring fordeviations in equilibrium moisturecontent caused by up to a 5% change inrelative humidity. A change of 8–10% inthe relative humidity is considered tobe a critical threshold for dimensionalchanges in the paper.

Recommended humidity and temperature levels

Influence of humidity

FLATNESS AND HUMIDITY

Depending on the relative humidity, the paper’s plant-derived fibres can gainor lose moisture, resulting in the fibres either swelling or shrinking,respectively. As a result, the fibres either grow longer (swelling) or becomenarrower (shrinking). These specific changes to fibre width and length result inthe paper sheets losing their flatness, causing problems such asmisregistration, doubling and wrinkling.

Dimensional changes

1 Corners and edges become curved

2 Humidity affects runnability

3 Crucial for sheet-fed offset: flatness

4 Lack of flatness in the stack

5 Paper moisture and relative humidity

6 Tight edges

7 Wavy edges

Application Temperature (°C) Relative Humidity (%)

Paper storage 18 – 20 60 – 65

Pre-press 20 – 22 45 – 55

Sheet/web-fed printing 20 50 – 60

Digital printing 20 – 22 45 – 55

Screen printing 22 50 – 60

Post-press 20 – 22 50 – 60

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The term “electrostatic” refers to apositive or negative charge on materialsurfaces that is unable to dissipate. Inthe printing industry, static electricityprimarily builds up on materials to beprocessed as a result of friction orsudden separation – such as whenfeeding the material through theprinting machine.

In the printing process, rolls and sheetsof paper are exposed to high levels offriction from guide rollers and thus arisk of static electricity – especially ifrollers are coated with rubber or plastic,which cannot dissipate charge sincethey are excellent insulators.

Humidity increases conductivityPaper is a weak conductor of electricityand its conductivity increases when itabsorbs moisture. If its moisturecontent is sufficiently high, the paper’s conductivity is improved

to a level where it can easily dissipateelectrical charge.

On non-conducting surfaces such asplastic rollers or inorganic printingstock, such as foils, a thin film ofmoisture is formed, which makes thesurface conductive enough that adangerous build-up of electrical chargecannot occur.

Problems with electrostaticA critical lower limit for preventing thebuild-up of electrostatic charge isconsidered to be relative humidity of40% for the stack and a relativehumidity of 45–50% in the press room.If values drop below this limit, then theattractive forces unleashed can causemultiple sheets to be fed into theprinting machine from the input stack,resulting in malfunctions within thepaper handling process.

Materials with low grammagesrespond more dynamically to staticelectricity than papers with a higherweight. In addition, the temporary aircushion separating the printed sheetson the output stack can dissipate tooquickly, causing set-off of fresh printingink onto the back of the new sheet.Poor paper handling in the printingmachine can also result inmisregistration and a substandardprinted image.

In web-fed offset, excessiveelectrostatic charge often causesproblems in the folding unit or foldedsheet stack. In port-press and bookbinding, problems with sticking to thefolding unit feeder or misfeeding intogathering pockets and cover feederattachments are also caused by staticelectricity.

The build-up of electrostatic charge can cause serious problems when working with paper, foil and packaging. Static electricity is the typical result when non-conducting or poorly conducting materials are subject to rapid friction or sudden separation. Optimal humidity promotes the harmlessdissipation of electrical charge.

STATIC ELECTRICITY AND HUMIDITY

A highly-charged atmosphere

CONSEQUENCES OF ELECTROSTATIC BUILD-UP

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Web-fed offsetCompared to sheet-fed offset, web-fedoffset is less sensitive with regards tohumidity. Serious problems can occurif relative humidity is too low in theareas where roll stands are used tostore unpacked paper rolls beingprepared for splicing. Here, optimalconditions are assured by a targethumidity of 50–60%.

If this is not provided, two factors canlead to significant problems inproduction. First, the external layers ofthe paper rolls can lose moisture andstart to dry out. The shrinkage thatresults then causes significant tensionin the paper, leading to tears in theouter layers or breakages in the splicebetween the end of one roll and the“roll nose”, i. e. the start of the next roll.

In addition, the paste on the preparedrolls can also dry out prematurely. This

results in pasting errors during theautomated roll changing procedure orweb breaks at the pasting point as thepaper is fed through the machine.Other negative consequences caninclude additional spoilage, productionstoppages and potential delays inoutbound delivery.

Digital printingAs with conventional offset printing,dimensional changes in the material tobe processed and the build-up ofelectrostatic charge are the keyproblems that are caused by air that istoo dry. A lack of humidity also has astronger effect on print quality than in offset.

If electrostatic charge builds up withinthe machine due to rapid frictionalprocesses, the pigments can bedeflected in a diffuse manner betweenthe machine and printing stock. The

result is an uneven printed image thatappears “cloudy”, i. e. having alternatebright and dark patches.

PackagingIn packaging printing and production,optimal humidity is also one of themost important climatic parameters.For the punching and bonding ofchromo-duplex board, a sufficientlyhigh level of humidity guards againstdimensional changes while ensuring a 100% fit for the final, assembledproducts.

When processing and laminatingsynthetic foils, problems with materialssticking together, material handlingdifficulties, set-off issues, creasing anddisruptions in ink transfer can all beavoided.

Humidity is the solution

QUALITY CONTROL WITH HUMIDIFICATION

SELECTED PRODUCTION PROCESSES

The right humidity is a quality factor for many production techniques in theprinting and packaging industry. For many specialised applications andtechniques, only a trouble-free production process without delays and at theright quality can guarantee the desired level of productivity and profitability.

Static electricity

1 Humidity reduces static electricity

2 Multiple sheets pulled off the input stack

3 Misfed sheets

4 Sheets stick together

5 Polypropylene plates become charged

6 Pasted joins dry out

7 Synthetic foils

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Image: Fogra

The quantity of calcium andmagnesium salts – which determinethe overall hardness of the water – hasa substantial influence on print quality.Calcium and magnesium ions have theability to bind to the saponifiablecompounds in printing inks to forminsoluble “lime soaps”.

In the printing machine, theseinsoluble solids are deposited on theinking rollers, making theseincreasingly hydrophilic and therebyimpairing the quality of ink transfer.One effect on the ink rollers is “glazing”,i.e. printing ink is no longer smoothlytransferred from the ink fountain to theprinting plate. The perfect fountainwater has an overall hardness of 10–13°e CaCo3/qql. In this region ofaverage hardness, the formation of“lime soaps” is no longer a problem.

Optimal pH valueAlongside overall hardness, the printingprocess is also strongly affected by the

proportion of hydrogen carbonate.Hydrogen carbonate neutralises acids,thereby influencing pH. In offsetprinting, the fountain solution’soptimal pH value for printing is slightlyacidic, in the pH range 4.8 to 5.5.Fountain solution additives arebuffered to keep the pH valueconsistent even in the event of factorscaused by papers or inks.

If untreated mains water has ahydrogen carbonate content of over150 mg/l, some of the acid buffer willbe neutralised. Fluctuations in the pHvalue lead to difficulties with printing,such as delays in drying, toning andexcessive emulsification.

CorrosionFor corrosive constituents found inwater, namely chlorides, sulphates andnitrates, printing machine makersdefine maximum limits, as thesecompounds are highly damaging.Treated process water protects against

corrosion and can increase roller servicelife by as much as 70%. Other directcost-saving potential results fromsavings made on alcohols and otherfountain solution additives such asisopropanol (IPA), and the reduced needfor routine cleaning.

Water quality = process qualityWith a water treatment system, anydrinking water supply can be used toproduce standardised process waterthat has constant hardness and a lowhydrogen carbonate content, and isfree from corrosion-promoting saltsand microorganisms. A cost effectiveadditional benefit is also possible if the treated water can also be utilisedfor humidification.

In print shops, water is used in many applications – in rubber blanket washingfacilities, for humidification and for fountain solution production in particular.Untreated water from the mains cannot be used as process water in any of theseareas. The reason for this is to be found in the large number of substances inwater that can cause serious problems.

PROCESS WATER

The right water is the key!

ADVANTAGES OF TREATED FOUNTAIN WATER

200 400 600 800 1000

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600

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Abso

rbed

hea

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Evaporated water (in l/h)

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Temperature (in °C)15,5Re

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18 21 24 27 30 3220304050607080

Temperature plays a crucial role in therelationship between paper and air: therelative humidity of a room depends onthe ambient temperature. A change of1°C in the temperature corresponds toa change in relative humidity of about3%. As the temperature falls, therelative humidity rises. Conversely,relative humidity itself falls astemperatures rise – always assumingthat absolute humidity remains thesame (see fig. 6).

For most production processes in theprinting, paper and packagingindustries, optimal climatic conditionsare typically achieved with a relativehumidity of 50–60% and a roomtemperature of 20–22°C.

Much too warmHeat gains from machinery inproduction and post-productionfacilities are typically so severe that

temperatures are much higher thanrecommended values. Oneconsequence of this is a drop in relativehumidity – with serious consequencesfor material handling and processstability. Personnel also suffer by beingexposed to these adverse workingconditions. By controlling the roomtemperature, businesses can make auseful contribution to quality control aswell as increasing employee comfort.

Evaporative coolingClimate control in production facilitiesoften requires a lot of cooling, resultingin high energy costs. With the rightdesign and technology a direct roomhumidification system can reduce thecosts of air conditioning or simplyreduce the room temperatureindependently of any AC system. This isdue to the positive side effect of thehigh-pressure nozzles, which spray coldwater at 85 bar directly into the room’s

air without causing droplets. Thecomplete absorption of themicroscopic, atomised water dropletsin the air causes heat to be drawn outof the room. The principle ofevaporative cooling achieves anextremely cost effective lowering of theroom temperature. 100l water from ahigh-pressure humidification systemabsorbs around 70kW heat whileconsuming only 0.6kW of energy,achieving a potential reduction in roomtemperature of between 2°C and 5°C.

Low-cost cooling

COOLING

High temperatures in production areas are a burden on personnel, plant andprocess materials. On the other hand, the cooling of production rooms requiresa lot of cooling capacity, resulting in high energy costs. With a direct roomhumidification system using high-pressure nozzles, the cost of climate controlcan be significantly reduced.

Process water and cooling

1 pH value of 4.8 to 5.5 is optimal

2 Water determines printing quality

3 Colour rub-off due to drying problems

4 Corrosion reduces roller service life

5 Humidification absorbs heat

6 Temperature and relative humidity

7 High-pressure nozzle humidifier

EVAPORATIVE COOLING WITH HUMIDIFICATION

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1Water and high pressure

AirSteam

Steam

Air

Aerosols

Water supply

In general, we can distinguish betweentwo basic principles in humidification:direct and indirect humidification. Witha direct room humidification system,separate humidification units areinstalled directly in the room, and areclearly visible. With indirecthumidification, moisture is added tothe air in centralised air-conditioningsystem and fed into the working area by using a system of ducts andoutlets. In the printing industry, direct humidification systems aremainly used, primarily because theyoffer more targeted and tailoredcontrol over humidification.

Production areas used for differentkinds of work and with differenthumidification requirements – such aspaper storage, pre-press and post-press– can be humidified precisely accordingto demand. For specialised machineryand applications, targeted “spothumidification” for areas or materials can

also be implemented, to ensure higherlevels of humidification as needed.

TechnologiesThe technologies available today foruse in direct room humidificationsystems vary in terms of their energyconsumption, maintenance costs andhumidification capacity. Withevaporators, a fan is used to draw inroom air, which is then passed over amoist wick. The humidification processitself is caused by evaporation from thesurface of the wick.

While these kinds of humidifiersrequire very little electricity to run,humidity control is limited to around+/-10% and the evaporator wicks willneed regular cleaning, inspection andpotentially replacement to combatmicrobial growth.

Steam-based humidifiers generatesteam in a heatproof plastic or

stainless steel cylinder, in which thewater is heated to 100°C. Steamhumidifiers are hygienic, sincemicrobes and bacteria are reliably killedoff by this process. For electric steamhumidifiers, energy consumption ishigh, as are the service requirements,due to the need to manage the limescale that builds up.

With spray humidifiers, water isaerosolised allowing it to be readilyabsorbed by the air. The aerosolisationprocess can either be carried out withultrasonic oscillators, through the useof compressed air or by spraying thewater under high pressure.

Spray humidifiers can humidify largeinterior spaces while consuming verylittle energy. The use of watertreatment plant in combination with these systems removes mineralsfrom the supply water, providing dust-free humidification.

To ensure adequate humidity, the printing industry uses a wide range ofsystems and technologies. Nozzle or ultrasonic fogging units, steamhumidifiers and evaporators are the kinds of technologies typically deployed,and differ in terms of energy consumption, maintenance requirements andhumidification performance.

HUMIDIFICATION TECHNOLOGY

One goal, multiple options

AN OVERVIEW OF POTENTIAL SYSTEMS

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State-of-the-art technologyIn recent years, many companies havereplaced steam and compressed-airhumidifiers with high-pressure nozzlesystems. These systems use a high-pressure pump and special nozzles toatomise the water into a fine mist aspart of a virtually silent process.

Energy consumption is also only afraction of typical values for nozzlespowered by compressed air or steamhumidifiers. The adiabatic coolingeffect of cold water evaporation alsocreates a pleasant indoor climate. Toensure operation is hygienic andtrouble-free, only ultra-pure,demineralised water is used – provided by a reverse osmosis plantthat is integrated into thehumidification system.

In facilities where the water treated foruse in the humidification system canalso be used as standardised processwater for the printing presses, there is a practical and cost-effective additional benefit.

Maintenance is a mustA humidification system is only ashygienic, safe and reliable as theprocess water, and the service andmaintenance model that is in effect.Even if it appears clear and pure, and isperfectly suitable for use as drinkingwater, untreated water will typically beunsuitable for use in mosthumidification systems.

This is because of the large number ofsubstances found in water: bacteria,microbes, algae, suspended particles,salts and other minerals can pose athreat both to human health and thefunctional capability of humidifiers.Typically, a reverse osmosis plant isused for the treatment of the water tobe used in humidification systems.

Despite optimal pre-treatment ofmains water with a softener andfiltration stages, undesirable depositscan still form on reverse osmosismembranes and other key componentswithin a humidification system. Theseare not only capable of seriouslycompromising the performance andservice life of the plant, but also – andabove all – present a serious risk tohuman health.

Routine inspections, maintenance,disinfection and the replacement ofheavily worn system components aretherefore absolutely essential for thesafe and hygienic operation of thehumidification plant.

Details of the hygiene standards of thevarious humidification systems can beobtained from certificates issued byindependent testing labs and frommanufacturers’ maintenance andservice programmes.

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HUMIDIFICATION TECHNOLOGYHYGIENE AND MAINTENANCE

Humidification technology

1 High-pressure nozzle humidifiers

2 Steam humidifiers

3 Ultrasonic humidifiers

4 Water treatment for high-pressure nozzles

5 Microbes and bacteria must be avoided

6 Routine maintenance

7 Internal hygiene monitoring

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Every year, over 6,000 delegates fromthe EMEA region visit the Demo andTraining Centre of this leading digitalprinting specialist to seek inspirationand participate in training. The Spanishsite views itself as “Dream Factory” thataims to stimulate and foster newcustomer product ideas, anddemonstrate the digital printingtechniques for turning them into reality.

To ensure optimal results for print andproduction, the HP Demo and TrainingCentre requires air humidity values tobe kept constant. “Electrostatic charge,changes to the paper dimensions andfluctuations in print quality alladversely affect our training anddemonstration work,” explains HPTrainings Manager Adam Goldthorp.“In addition”, says Goldthorp,“thevarious printing technologies andmaterials (e.g. plastic, cardboard) alsoneed different levels of humidity forprocessing.” The existing centralised

ventilation system with steamhumidification was no longer able to handle the requirements and wasaccordingly decommissioned. Since2013, a direct room humidificationsystem with high-pressure nozzles has been ensuring constant, optimal humidity.

Simple installationOver 50 high-pressure DRAABETurboFog Neo humidifier unitsguarantee controlled humidification invarious areas and parts of the building.Forinstallation, HP Inc. merely requireda mains water system and drain, plusan appropriate electricity supply.

Everything is supplied to the buildingfrom a central mechanical room, whereboth the water treatment systems andthe high-pressure pump are installed.These systems are connected to thehumidifiers using specialised high-pressure hoses and control lines. The

compact humidifiers, attached toceiling suspension or wall-mounted areeach oriented both horizontally andvertically in the various rooms toensure optimal humidity distribution.High-pressure nozzles spray out anultra-fine fog with a droplet size of lessthan 15 μm, which is immediatelyabsorbed by the air and uniformlydistributed within the room.

Lower energy costsThe required humidity is regulatedusing a digital control system. In eachof the individually definedhumidification zones (rooms or parts ofrooms), control units measure thecurrent level of humidity and activatethe humidifiers when it falls below theset target value. This means that roomscan be humidified individually, orexactly as required for their varioususes.

At its 4,000 sqm Demo and Training Centre in Sant Cugat del Vallès (Barcelona),HP Inc. presents its customers with the latest digital printing technology, fromlarge-format printing to packaging and job printing. To ensure optimal resultsfor print and production, the HP Demo and Training Centre requires airhumidity values to be kept constant.

CASE STUDY

Speed and quality in digital printing

HP INC., BARCELONA

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For José Baena from HP Inc. Global RealEstate, the new technology offersmajor advantages: “We now haveoptimal values across the various zonesand printing systems. And we’ve alsomanaged to cut energy consumptionfor humidification by over 95%.” Theenergy-efficient high-pressurehumidification system ensures aconstant relative humidity of 50–65%.

Depending on the printing process andmaterial, the relative humidity in theDemo and Training Centre can beadjusted quickly – and increased forprinting onto plastics, for example.

Automated maintenanceBoth the high-pressure system and thecorresponding water treatment unitare installed in small portablecontainers that allow quickreplacement and servicing. The reverseosmosis system used for watertreatment de-mineralises and cleansthe mains water of impurities. Every sixmonths, these containers areautomatically replaced at HP Inc. withfully maintained and cleaned systems.

The used systems can be easilyreleased from their wall brackets andsent back to the manufacturer forservicing where they are dismantled,inspected, rinsed out and cleaned.Worn parts are replaced and technicalupdates installed.

Humidity is a mustFor HP Inc., zero maintenance, all-inclusive service and the individualhumidification solutions were the keyreasons for picking the new high-pressure nozzle-based technology.

Since then, the DRAABE humidificationsystem has been providing individuallyadjusted, optimal humidity throughoutthe Demo and Training Centre, so as toprotect against static electricity anddimensional changes in printing stock.

Impressed by the positive experiencegained in their use, HP Inc. also deployshigh-pressure nozzle systems forquality control at international tradefairs: at drupa 2016, the world’sflagship trade fair for the printingindustry, an entire exhibition hall wasfitted out with a humidificationsystem. “My team and I were reallypleased to see the effects of a perfectlybalanced relative humidity on ourmachine demos and the general roomclimate,” reports Rotem SagiShteinmetz, Operations Manager in HPInc.’s drupa Team, summarising theimportance of optimal room humidity.

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Fact file

Humidification: 54 high-pressure fogging units

Space: 18,000 m3

Required humidity: 50 to 65 % RH

Commissioning: 2013

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CASE STUDY

HP Inc., Barcelona

1 Demo and Training Centre

2 Humidity protects against static electricity

3 High-pressure nozzle humidifier

4 Individual positioning

5 Replaceable water treatment units

6 Rotem Sagi Shteinmetz

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“More than machines” is the claimasserted for the two fully equipped printshops, spread over an area of about10,000m2, where the primary focus is onthe integrated overall processes and therequired components. With itscomprehensive portfolio of offset anddigital machines, software,consumables and services, the PMCcovers any and every topic likely to befaced by a modern, industrial-scale printproduction business.

Over 1,200 individual customer demosare held yearly, educating internationaldelegates in how real-world productionprocesses can be organised to be moreeconomical and more reliable. The PrintMedia Centre Heidelberg forms part ofthe Global Print Media Centre Network.Other members include the PrintMedia Centre Atlanta in Kennesaw andthe Print Media Centre Shanghai inQingpu, which serve the US and Asianmarkets respectively.

Fault-free sheet feedingTo ensure optimal climatic conditionsfor machine demonstration work, thePMC Commercial, opened in 2015,controls relative humidity with a high-pressure nozzle system featuring thelatest generation of humidifiers. “Ourpresentations have to be right on themoney and must not be disrupted bywavy or tight edges or electrostaticbuild-up on the paper. Perfect sheetfeeding is a basic requirements for ourdemonstrations,” explains Head ofPrint Media Centre Roland Krapp.

In choosing its humidification system,Heidelberg can draw on almost 20years of experience: the first high-pressure humidifiers were installed inHeidelberg’s manufacturing facilitiesback in 1996. Over 200 units are now in use, ensuring that printing andtesting in the assembling halls proceedas intended.

Water treatmentThe right water plays a major role inensuring the quality of offset printingat PMC Commercial. Accordingly, germ-free, demineralised water is producedas part of a multi-stage process bothfor the high-pressure nozzle foggingunits and as specially treated processwater for the printing machines.

The process begins with watersoftening. Here, the calcium andmagnesium salts responsible for waterhardness are replaced with readilysoluble sodium salts. Once treated, thissoft water is then purified by beingpassed through a two-step mechanicalfilter stage.

With the Print Media Centre (PMC) Commercial and Packaging, HeidelbergerDruckmaschinen AG in Wiesloch-Walldorf operates the world’s largestshowroom for commercial and packaging printing. Optimal humidity andstandardised process water increase performance while ensuring a trouble-free printing process.

CASE STUDY

More than machines

HEIDELBERGER DRUCKMASCHINEN AG, WIESLOCH-WALLDORF

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This separates out solid contaminantswith a particle size of up to five-thousandths of a mm. The heart of thewater purification process is the thirdstage, reverse osmosis.

Here, a membrane separationtechnique is used to effectively steriliseand demineralise the pre-treated water.The reverse osmosis process is entirelyself-contained and runs in a portable,compact module that enables thecomprehensive maintenance anddisinfection of the plant by simplyreplacing the entire module.

This standard service is performed bythe manufacturer automatically athalf-yearly intervals. From the reverseosmosis plant, some of the pure waterproduced is fed directly to thehumidification system.

Process water as an additional benefitTo produce the fountain solution, the95% demineralised water passesthrough a fourth process stage, inwhich a specialised hardnessconcentrate is added to the water.

After this standardising step, theprocess water now has a residualhardness optimised for offset printingand is routed to the Heidelberg printingmachines via a separate supply line.Some of the treated water is also heldin reserve as a fountain solution forsubsequent use, in a separate tank.

By deploying this standardised processwater, Heidelberg ensures that theink/water balance for the ink in themachines remains stable, and thattoning, roller glazing or setoff does notoccur. The water has a constant quality,with a pH value between 4.8 and 5.5and a hydrogen carbonate content ofless than 150mg/l.

For personnel and plantAt Print Media Center Commercial,optimal humidity and standardisedprocess water are key parameters thatguarantee maximum performancewhile avoiding disruptions to theprinting process.

In selecting its humidification system,Heidelberger Druckmaschinen AG hasdevoted particular attention tomaximising operational reliability andconstant hygiene, emphasises RolandKnapp: “Requirements for occupationalsafety and health as well asmaintainability were reviewed in greatdepth by the specialist departmentsbeforehand. And we are very happywith the result: Our newhumidification system reliably creates the conditions required for peak performance by our personneland plant.”

Fact file

Humidification: 36 high-pressurefogging units

Space: 4,700 m3

Required humidity: 45 % RH

Commissioning: 2015

CASE STUDY

Heidelberger Druckmaschinen AG

1 Print Media Center Commercial

2 Printing machine at PMC

3 High-pressure nozzle humidifier

4 Optimal: humidity and process water

5 Water treatment at PMC Commercial

6 Expert know-how at Heidelberg

i

HUMIDITY AND PROCESS WATER

This brochure has been produced in closeconsultation with Fogra.

We thank Fogra warmly for their support and the photographic material supplied:

FOGRA Graphic Technology Research Associationwww.fogra.org

12/2018

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