High Tech Humidification - dristeem-media.com

1 Page high tech Humidificationby Kendall BrantEnvironmental Test FacilitiesEnvironmental testing is usually of two broad types, climate and dynamic . Climate testing includes temperature, humidity, salt spray, fungus, and combinations of the testing includes vibration shock, acceleration, radiation, and other forms of stress. Multiple usage chambers usually have a wide range of capability in temperature and humidity. Humidity requirements may range from 2% to 98% RH over a temperature range of 35 F to 185 F (2 to 85 C).Direct injection of steam from an in-plant boiler, assuming boiler chemicals are not objectionable, is suitable for high temperatures and humidities and where quick and accurate response to control is necessary.

2 Modulating control is necessary where a precise humidity level is required. When high purity water vapor is required, various types of vapor generators using demineralized water for make-up, can be employed. Care is necessary to avoid causing wet areas in ducts where bacteria could be harbored. In some cases, where extreme reliability of temperature and humidity control are needed, a dual system (direct steam injection and vapor generator) may be HumidificationBecause many labs are operating in clean-room environments, they require high levels of air changes. Laboratories generally are of four types: biological, chemical, physical and animal. Biological labs support research on scientific disciplines, such as biochemistry, microbiology, cell biology, biotechnology, immunology, botany, pharmacology, and labs support organic and inorganic synthesis and analytical functions.

3 Some organic and inorganic chemicals are hygroscopically affected by the RH levels. Some chemical reactions are triggered by atmospheric moisture. Humidity must be controlled for elimination of static electricity and for precise dimensional requirements. Page Physical labs support experimental processes involving physics including lasers, optics, nuclear, electronics, etc. Humidity must be controlled for the elimination of static electricity and for precise dimensional labs support housing of the animals used in medical research and the treatments performed. These labs require narrow ranges of humidity and temperature SpacesHeat removal and proper humidity control throughout the year is a requirement of most computer and related equipment installations.

4 Auxiliary devices and supplies (magnetic tape, disc packs, cartridges, data cells, and paper) should be kept in atmospheric conditions similar to those in the computer room. If this is not possible, they may require conditioning or tempering under computer-room atmospheric conditions for a period prior to some earlier installations, cooling air was supplied directly into the hardware. In those cases, the air stream must not be allowed to exceed 80% relative humidity because doing so may adversely affect some of the components, particularly those made of gold and , computer rooms are designed for a temperature of 72 F (22 C) and 45% relative humidity. To maintain proper relative humidity in a computer room, vapor transmission retarders sufficient to restrain moisture migration during the maximum expected vapor pressure differences between the computer room and surrounding areas, should be installed around the entire envelope.

5 Cable and pipe entrances should be sealed and caulked with a vapor-proof material. Door jambs should fit tightly. Windows in colder climates must be of the insulated glass systems should provide only enough outdoor air for personnel requirements and to maintain the room under a positive pressure relative to surrounding spaces. In most computer rooms, an outdoor air quantity of less than 5% of total supply air will satisfy ventilation requirements and prevent inward leakage. Outdoor air in excess of the required minimum increases the cooling and heating loads and makes control of atmospheric contaminants and winter humidity more order to minimize the dehumidification effect of the cooling coil, the coil should be selected to operate at a sensible heat ratio of.

6 9 to (dry coil) at 72 F (22 C), and 45% relative humidity. When applying Humidification apparatus, the moisture should be supplied on the leaving side of the cooling , self contained (packaged) air conditioners are used in these applications. They usually discharge the air vertically downward into a raised floor cavity. Locating the humidifier downstream of the cooling coil usually requires the Page Humidification to be introduced inside the air conditioner since there is no duct space for this Humidification methods are used including direct boiler steam injection, electrode cylinder type vapor generators, electric hot element vapor generators, infrared evaporators and sometimes wetted media This industry relies heavily on Humidification to minimize malfunctions in electronic switching stations.

7 Inadequate humidity causes equipment failures due to the attraction of very fine dust particles to the sensitive electronic devices in use. Many of the smaller switching stations are unmanned and are visited on an as needed schedule for inspection and periodic maintenance. Such being the case, the humidifiers must be of a type and style that can operate without fail for extended periods. This usually requires types that utilize softened or demineralized water for make-up. Further, they must not add dust particles to the Room Humidification Key Issues for Humidifying a cleanroom environment*Cleanrooms are one of the most demanding environments to humidify, as they require particulate-free humidity delivered at a rate to meet relative humidity tolerances as low as 1 per cent.

8 Choosing a Humidification system for a cleanroom environment will depend upon several factors: existing energy sources (such as a boiler), tolerance for going offline for maintenance, the type of humidity control required (humidity or dew point control), existing temperature and humidity factors, and available absorption types and energy sourcesThere are two basic types of Humidification systems: isothermal and adiabatic. Isothermal systems use electricity, natural gas, hot water or boiler steam to boil water into steam for Humidification . Existing boilers can be used as an energy source by diverting boiler steam through a heat exchanger to make steam for Humidification .

9 Direct injection for chemical treated boiler steam into cleanrooms is not advised. An adiabatic system, such as a fogger system which disperses fine water droplets into the air using compressed air, uses heat from the surrounding air to change water into vapour for Humidification . Because of the resulting temperature drop (typically 15 degrees C in make-up air) this system may require additional expense to preheat the air for necessary absorption to systems that use softened or standard water often cycle through scheduled water skimming, draining, and flushing to remove precipitated minerals. This causes steam production to temporarily stop, and humidify levels to fluctuate.

10 Deionised systems do not require such cycles, as there are no minerals to remove. Page The make-up water is continuously replaced by a modulation float valve, allowing the system to remain continuously online, providing consistent steam output. Both adiabatic and isothermal systems can meet the reliability requirements of cleanrooms, with each system having distinct benefits. Generally, the fewer moving parts a system has, the more reliable it is. By that standard, adiabatic fogging systems will be the most reliable. They have no moving parts and require minimal maintenance, and thus are virtually always online. But for many applications, isothermal systems are more appropriate.