Like charity, it seems that the environment begins at home. While plenty of printers are pouring money and resources into reducing emissions, effluent and waste released into external atmosphere, inside many a factory the air quality remains neglected. At best, there may be an air-conditioning unit that keeps the ambient temperature at bearable levels in the summer months. But most printers aren’t aware of the productivity – and therefore hard cash – benefits that can arise from optimising the pressroom environment. “It’s not just a case of being altruistic and nice to your staff,” says John Barker, UK sales manager of humidity control expert Draabe. “There are good, solid payback reasons for getting the air quality right.”

　　The average print factory floor is not necessarily a benign environment for human health. Setting aside ‘avoidable’ industrial risks such as lifting heavy weights and eyestrain from computer monitors, the air quality and atmosphere inside the factory – which, since all workers have to breathe, is not classed as an ‘avoidable risk’ – is under threat from a combination of factors; the main three being temperature, humidity levels and airborne pollutants.

　　Preventing paper curl

　　Temperature and humidity level are intimately related: a temperature rise of 1°C causes humidity levels to drop by 2%, and printers are rarely in control of their factory’s ambient temperature, as it’s usually pushed upwards by presses and finishing kit. Low humidity – a problem that dogs printers in the UK – causes a big problem for paper: curl. Barker explains: “When you unwrap paper from its vapour seal and store it in a dry atmosphere, it dries out. But the edges dry out faster than the middle, which gives you paper curl, and that means it doesn’t feed well on the press.” Printers with a paper curl problem must either run the press slower, or start and stop the press for jams.

　　Static is another low-humidity problem for printers. The phenomenon of the 1m stack at the infeed that makes for a 2m stack on the delivery side is well known in the average sheetfed print factory: the sheets are separated by the static that builds up on each sheet. This happens normally in factories, but in atmospheres where the humidity level is over 50%, the ambient air contains enough moisture to earth that static charge back down to the ground naturally. Some printers use pile turners with air-blowers that minimise static, or fit anti-static bars on their presses and finishing kit. But a good humidity control system will do the job in the background, without any need for a separate stage in the production chain. Humidifiers work by spraying short bursts of pressurised, purified water through nozzles, which evaporates, taking heat from the surrounding air to cool it down.

　　Clarkeprint in Birmingham installed its humidity control system three years ago to deal specifically with paper curl. Director Paul Clarke says the company was doing a lot of stationery work at the time, “and we needed to be able to guarantee to our customers that the sheets would go through their laser printers, but we were getting so much curl and that caused problems.” The system, he says, reduced those and made for “much happier customers”.

　　In addition to humidity and temperature factors, the atmosphere in any print factory potentially contains higher-than-average level of airborne pollutants. Typical pollutants divide into two kinds: fumes, such as VOCs and other solvents; and particulate matter, such as dust and anti-setoff powders.

　　Solvent control

　　Fumes in a typical print factory include high levels of VOCs in inks and fount solutions. Solvents can irritate the skin, eyes and lungs and cause headaches, nausea and dizziness, and VOC levels can be particularly high in large-format digital print shops using solvent-based printers. While most digital printers incorporate some mechanisms for either containing or removing their fumes, there are also third-party products available that capture the VOCs at source – used on printers that don’t have any integrated fume-removal system. PAT Technology’s CaptivAir is one such: it’s effectively a box that sucks all the fumes away from the printer, purifying them before exhausting the cleaned air back into the room. PAT has also developed a range of air quality treatment systems intended to eliminate dust and debris while maintaining optimal humidity levels inside pre-press equipment – particularly ablative CTP devices (which work by scouring off small particles of the plate coating) and digital inkjet proofers.

　　Eliminating alcohol also contributes to the air quality on a typical print shop floor. Several printers in the UK trialled waterless print technology when it first emerged in the 1990s, but have since rejected it as “hard to control and producing inconsistent results,” according to Richard Owers, sales and marketing director of Beacon Press. Instead, Beacon found an alcohol elimination system, known as Optimizer, developed by German process control outfit Eurografica, which works with MAN Roland on the optimisation of its presses. Using the Optimizer technology has allowed Beacon to eliminate its IPA-content fount solution additives altogether, and Owers says the equipment will pay for itself in a relatively short time as Beacon no longer needs to pay for IPA, nor pay to dispose of it. “It also makes for a steady decline in factory-to-air emission readings and a safer, more pleasant working environment for our staff,” he says.

　　Ongoing improvements

　　Improving air quality isn’t simply a matter of investing in new gadgetry, however, as Greenhouse Graphics in Basingstoke shows. The company has focused on reducing its use of IPA on-press. Director Timi van Houten explains that Greenhouse’s policy of sustainable print (collated into a single raft of initiatives that the company dubs ‘ecoprint system 4’) is a cost-saving for the company, but also benefits the wider environment and individual employees by providing a better environment to work in. “Everybody wins. And there’s no capital investment involved, although it is demanding of time.”

　　For printers, one of the biggest environmental challenges is airborne ‘particulate matter’ – ie, paper dust from the press or bindery together with dust generated by human bodies from sweat, hair and skin particles. Printers using lots of anti-set-off powders can also generate powder dust. Too high a level of particulate matter in the air can cause quality problems on the press – hickeys and general artefacting are common – and can badly affect the air quality for staff.

　　Removing particulate matter from the factory’s air supply is often done by vented filtration systems – so-called air-scrubbers. These can be any size from a free-standing box situated at the place where the particulate matter is generated, to a factory-wide system linked to all areas by pipes and vents to a central filter that returns cleaned-up air into the factory. However, air-scrubbers increasingly have a bad reputation among environmental specialists: “Because they operate at one remove from the equipment or process that generates the airborne particles, those particles are allowed to circulate before being sucked out of the air,” says PAT Technology vice-president of sales and marketing Sylvain Lafrenière. “Which can mean that operators get to breathe the particles, or they get to wander out of the door or window and into the wider atmosphere.”

　　Filtration systems also remove airborne contaminants that aren’t necessarily visible or even tangible – including pollen, fibres, bacteria and smoke. All types of filtration system use filters that may be consumables, and legislation requires for ventilation to be cleaned on a regular basis – so printers that install these systems should factor in charges for replacement filters and cleaning/maintenance.

　　But while there are plenty of business benefits in improving ambient environment, it’s not just carrot: there’s plenty of stick as well. As far as staff go, employers have legal responsibilities to provide the appropriate quality of ambient environment. There are two main pieces of legislation that set this out. Under the Health & Safety at Work Act of 1974 (which were strengthened by the Health, Safety & Welfare Regulations 1992), employers are obliged to maintain a safe and healthy level of air quality. The long-familiar Control of Substances Hazardous to Health (COSHH) regulations of 1994 also state that employers engaged in ‘industrial processes’ – which includes printers – must carry out risk assessments to ensure that their indoor air quality is adequate. Prosecution is the penalty for failure to comply, but employees who feel their working air quality is inadequate also have the right to sue employers who don’t provide this.

 

[时间：2007-09-14  作者：Karen Charlesworth  来源：信息中心]