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if a shift outside of the window occurs , conditions will not be favourable . Less than then 40 %, there would be the risk of short circuiting due to static charge . Humidity above 65 % you increase the risk of corrosive conditions on the electronics . Each application would have specific ranges to maintain . Other examples in the medical arena are the need for high humidity in burn centres to assist healing , or low humidity in pharmaceutical manufacturing .
“ Variations in space temperature and humidity may modify the dimensions and mechanical properties of many materials .”
The world is also moving quickly towards accommodating healthy environments which includes all the places we live and work . Here humidity is not only about comfort anymore .
“ If you do not have enough moisture in a room , the dryer the air is the RH will decrease because of the expansion of the air . This means that breathing that air in , it is going to have a physical impact on occupants through drying out their sinus , it is going to dry the alveoli in their lungs and possibly progress further to de-hydration . On the converse , RH reaching 100 % is sufficient to germinate a spore , bacteria , or mould . Once this has happened , all you need is above 75 % RH and growth will continue . These scenarios need to be managed correctly in terms of achieving the best people-health , which is vital ,” says Andersen .
Other than healthy environments , electronics and processing sites , maintaining the correct humidity band is also important for other materials such as fabrics and items that rely on moisture levels such as wooden goods that can be damaged through continual environment changes . Other applications where humidity control is essential are places such as archives , libraries and museums that have a variety of materials under high levels of protection due to the nature and importance of what is often stored .
In fact , the inclusion of the optimal band of humidity can be applied to almost any item , procedure , or process to produce any goods we have access to today from the paper used to print this publication , the screen you use to consume digital media or the pen on your desk or workstation . Any process involving the use of hygroscopic materials would also be critically reliant
on the correct humidity . This could further include food stuffs such as sugar or salt mills , and grain silos , which are susceptible to clumping or coagulation .
EQUIPMENT FUNCTION AND DIFFERENTIATING METHODS As a brief overview of an extensive topic , humidity control in simple terms is either adding or removing moisture from the air and this can be achieved in several ways using different methods and sensors . We have to identify humidification and dehumidification as separate functions because the equipment for each outcome is different from the other and prevailing climate temperature conditions often determine what method is best suited for specification .
“ One type of humidifier typically boils water to create dry steam which could be supplied in air handling units . Dehumidification can be affected by a cooling coil followed by a reheating coil or resistance heater . Alternatively , desiccant dryers can be used if low relative humidity is necessary for the particular application . Custom solutions are possible through incorporation of these functions into bulk air supply or by direct in-space inclusion . However , a full design should be completed and is always recommended ,” Kotze says .
In some humidification techniques one must make sure that the water source is relatively pure to avoid trace elements being
A two-stage indirect evaporative adiabatic cooler / humidifier . The low energy footprint provides exceptional PUE ( power utilisation efficiency ).
Specialised Climate Engineering
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RACA Journal I September 2021 www . hvacronline . co . za