Heating and Ventilating


Humidity balancing act is key to preserving valuables

With the combination of high humidification and very low energy consumption, modern adiabatic cold-water humidifiers seem to present an attractive option says Andie Chessun
A PROPERLY humidified building can enhance the health and comfort of its occupants, helping prevent dry skin and sore eyes and throats, and reducing static build-up. However, rising energy costs and increasing environmental concerns continue to be key factors for developers and building managers when specifying service elements for their site.

Museum applications
Humidity is key for maintaining valuables such as those exhibited in museums and galleries. Many objects have fiscal, educational and historical value so it is of utmost importance to adhere to the correct storage atmosphere. The typical humidity level for antique books in museums and galleries is 40-50%rH and if this fluctuates more than 5%rH this can cause irreversible damage.

Paper is hygroscopic, which means it reacts to changes in the humidity level and can become frail due to too little humidity. Antique wood furniture and musical instruments can crack or warp and fluctuating humidity can cause paintings to peel. Cracks can appear in the canvas whilst the frame may become warped. Natural materials of sculptures shrink and crack due to variations in the humidity. A uniform air humidity matched to the material in question safeguards the artwork at their value.

Many artefacts in museums are owned by private collectors and are loaned out to the museum via a contractual agreement. The requirement for regulated air is therefore paramount as it now involves an insurance company and a private owner as well as the museum and the general public. Monetary value is therefore placed on ensuring top air quality. If the museum's relative humidity is of an unacceptable quality, then the artefact could be removed from the museum entirely. LAPADA (the Association of Art & Antiques Dealers) suggests for dealers to check humidity levels with a light meter and hygrometer during transport or storage.

Another factor to consider, and an everyday challenge, will be the number of people visiting these artefacts as fresh air can be let into the building or body heat can cause issues. In addition the outside weather will be a constant
consideration to maintain the humidity, heat and atmosphere. It is important to ensure that the correct humidification is specified for environments where such valuable objects are stored.

Occupant comfort
Humidification control is essential when it comes to preserving property, works of art, historical artefacts and materials. However, it is also becoming increasingly important to consider humidification control with regards to occupant comfort and health. Heating systems often dry internal air out, requiring the use of linked humidification systems. Having a healthy humidity level, especially within hospitals and offices, is beneficial as dry air can encourage the transfer of germs and creates an uncomfortable atmosphere.

With atomisers the humidifying water is atomised into very fine droplets, so-called aerosols. The energy required to change into the gaseous state, is taken by the droplets from the surrounding air in the form of heat energy. The atomisation therefore has a cooling (adiabatic) effect on the room temperature. The electrical energy requirement is particularly low for this type of humidification.

HygroMatik's Low Pressure Adiabatic System (LPS) range includes different classes of humidification performances at 45, 72 and 110 l/h thanks to performance optimised pumps which also help to reduce energy usage.

Adiabatic systems can offer a free cooling effect of up to 30 per cent, useful for taking some of the load from existing cooling systems. This provides a further saving on running costs in areas where cooling is required. Even during the winter months, some form of air cooling is often required, especially in areas with a large number of heat sources such as computers or other electronic devices or in data centres. All cold-water humidifying systems are adiabatic, taking heat from the air as the pressure of the released water vapour decreases.

With some pressured adiabatic systems able to work at capacities of up to 750l/hr, they are particularly suited to environments that demand large humidification loads, such as offices, data centres, airports, museums, production halls and laboratories.

When specifying products it is also important to consider how easy to maintain the system is. If individual components can be removed and easily serviced it means a product is fully maintainable, and older systems can be refurbished. This reduces the cost of servicing and also reduces the unnecessary waste produced by disposing of large groups of components or even whole systems.

Environmental concerns require a reduction in consumable, especially those classed as industrial waste. Manufacturers should be able to offer maintainable rather than disposable options, for instance cylinders. This avoids systems going to landfill.

Careful consideration
There are a wide range of systems being offered from a variety of manufacturers, including low pressure, high pressure, hybrid, surface evaporation and ultrasonic systems, and each of these different technologies offers a unique combination of features requiring careful consideration of the most suitable application situation. Selecting humidification systems also requires the balancing of a wide range of variables involving the customer's needs and the situation of the unit.

//The author is the national sales manager at HygroMatik UK//
22 January 2014


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