Feature Component protection Enclosing the


preventing condensation within vir- tually any product or packaging, explains the company.


answer to reducing moisture levels


To help protect electrical and electronic equipment, Brownell now provides a range of moisture adsorbing solutions such as static and panel-mounted desiccants, as well as technologies designed to maintain safe working pressures within enclosures


oisture can have a potentially devastating effect on electrical and electronic equipment. To help overcome the issue, Brownell offers a range of solutions, including desiccants and adsorbents, which are designed to reduce damaging moisture


M levels in products and


processes to a safe or acceptable level, and then maintain those levels. A desiccant is a hygroscopic sub- stance that induces or sustains a state of dryness desiccation in its vicinity, explains the company. Such materials have the ability to not only adsorb moisture, but can also be used in some purification and separation processes. An adsorbent material, meanwhile, the


has ability to extract certain


substances from gases, liquids or solids by causing them to adhere to its surface without changing the physical proper- ties of the adsorbent.


Adsorbing moisture


Among the desiccant products available from Brownell are static, panel- mounted and ultra-clean versions. The static desiccators are designed to protect electronic and electrical equip- ment against corrosion, dampness and contamination by reducing existing or incoming moisture to acceptable levels. The desiccators use adsorbing agents – either silica gel or molecular sieves – and have built-in saturation indicators which are blue when the humidity


14


adsorber is dry, and turn pink when the saturation level has been reached. According to the company, silica gel desiccators are generally used for appli- cations such as electrical and electronic systems which require long term preservation to reduce or prevent the formation of corrosion. The alterna- tive molecular sieve desiccators can maintain an ultra-low relative humidity for extremely sensitive applications such as optical and laser systems. These are said to be useful for equipment operating under extreme temperature conditions. The use of both static and panel- mounted desiccators can enhance the operating life of equipment as well as extending the safe working environ- mental limits in which equipment can work, explains Brownell.


Ultra-clean desiccators are designed to protect electro-optical, optical and laser systems, and the molecular sieves used within this type of desiccator will create a super dry environment, claims the company – typically down in the 100’s of ppm(V)


region (-30˚C


dewpoint). Creating this ‘super dry’ environment will prevent any change of state of the remaining water vapour from gas to liquid or ice.


Another solution is provided by


Brownell’s moisture adsorbing poly- mer which can be tailor shaped and fixed, providing an alternative to conventional desiccant bags for


Panel mounted desiccators protect electronic and electrical


equipment against corrosion,


dampness and contamination


WINTER/SPRING 2014 Enclosure & Panel Building Solutions Above:


Protecting against pressure build-up, waterproof


‘breathers’ help prevent water damage to


enclosures and instruments and can withstand total immersion in water


Being in sheet form, this can be easily cut, formed, punched, shaped and thermo-formed. It is supplied in a standard 297 x 210mm board. This, explains the company, ensures an excellent level of clean drying in a wide range of products – from electronics, machinery, optics and instruments to pharmaceuticals and food.


By allowing complex shaping and mechanical fixing, this humidity adsorbing board helps ensure maxi- mum space occupancy, which is increasingly required as a result of product miniaturisation.


Maintaining pressure With the lightweight materials used in the manufacture of today’s electronic products, designers either have to restrict the applications or increase the strength of the enclosure walls. However, heat can cause a pressure build-up within an enclosure and with- out adequate venting the lightweight material could fracture. Brownell’s Waterproof Breathers allow an enclosure to ‘breathe’ while withstanding driving rain or even total immersion in water up to 2m. The breathers can pass high flow rates of air which can result from rapid variations in pressure, caused by temperature or altitude changes. If a controlled environment within the equipment


is required, then a


humidity adsorber can be fitted in the rear of most immersion breathers. Another solution is pressure relief valves. According to Brownell, pressure relief valves allow designers to con- struct enclosures and instruments in lightweight materials with the valves maintaining safe working pressures. They can also be used in cargo contain- ers being transported by air.


Brownell T: 020 8965 9281 www.brownell.co.uk


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