Different types of locations, such as a textile mill, office, laboratory, or home have different requirements for relative humidity, due to which appropriate methods of humidification are utilized. Fundamental humidifying media, which have certain advantages and limitations, determine their suitability for a specific application:
Steam: It is simply a water vapor that only requires to be combined with the air.
Evaporative Pan: Air runs across the surface of heated water in a pan, and absorbs the water paper.
Water Spray: It is an adiabatic system, in which evaporation of the water is caused by the absorption of heat by water.
Requirements For Humidification
Capacity: When low capacity is required, steam humidifier, or evaporative pan media will be economical. For large capacity, steam humidification or water spray systems are suitable.
Maintenance: Steam humidification systems normally require less maintenance, while requirement of maintenance for the evaporative pan and water spray systems depend upon the contents of minerals in water. In water spray systems, spray nozzles can become blocked due to deposits of minerals, and may require regular cleaning.
Reaction to Control: Response to control in steam systems is better than the evaporative pan or the water systems because steam is simple water vapor which only requires to be mixed with the air.
Control of Output: Steam humidifiers can react more accurately to demands of system compared to the other systems. Evaporative pan and water spray systems function intermittently in response to control, and their output is determined by the size and number of spray nozzles or by water temperature and surface area respectively.
Corrosion: Corrosion occurs due to presence of moisture in any system. Sediments created in the unit, or in the steam, are drained from the humidifier through the drain trap. Corrosion in the evaporative pan systems depends on the materials used and the cleaning intervals. Water spray humidifiers are extremely vulnerable to corrosion.
Steam is normally used for production units, and where steam is not available, steam generating units are used. For higher range, central steam humidifiers are economical. An evaporative pan is suitable as a substitute to self-contained steam generating humidifiers for small commercial requirements. Water spray units are best suited for industries where evaporative cooling is necessary.