Digital printing: printing to perfection

Posted by Paul Langford on 13/05/20 10:00


Ensuring stable indoor conditions for digital printing is essential and can be costly. Achieving a constant temperature is fairly straightforward but a consistent humidity level is more challenging. First developed in the early 1990s, digital printing is a rapidly growing and sophisticated technology. Fast and reliable, it is however very dependent on having the correct print room conditions. The moisture content of the paper can affect the toner adhesion, paper jams and the fuser roller temperature.

Typically, paper is made with a moisture content of between 4 and 6 per cent. This should be stable in a relative humidity of 45-55%. in a room temperature of 22C. Digital printing companies know the importance of stable temperatures and humidity, but Colt has learnt that they may be spending more than they need to achieve these conditions.

While conventional air-conditioning units will control the temperature within very fine limits, they also dry the air, reducing the relative humidity. This means that they need to be combined with a re-humidification system. Often some kind of boiler based humidification system is used but these have a high energy consumption. We found, when consulting at a digital printing plant a few years ago, that the humidification system was using far more energy than the air conditioning. The alternative to conventional humidification systems is to use spray humidifiers, spraying water mist into the air. These systems need to be controlled carefully to avoid the possibility of legionella.

But what if you didn’t need to use humidifiers at all? In the instance above, we were able to supply direct evaporative coolers with humidity control. These provide the perfect answer. They can reduce the temperature within the room to acceptable limits for workers in summer. At the same time, the air is humidified as a by-product of the cooling process. Modern evaporative coolers which meet the requirements of VDI6022 (the widely accepted German standard) avoid the risks associated with legionella and actually clean the air.

This is a win-win for the customer. They have clean air at the right humidity. Using evaporative cooling uses far less electricity than a re-humidification system, and since our system provides part of the cooling load, the cost of running the air conditioning is also reduced. The business runs effectively, and saves money – which is what everybody wants and needs when running a business today. Find out more.


Topics: Climate Control