Products Technology file Desiccators with
saturation indicators Panel mounted desiccators from Brownell help to protect electronic and electrical equipment against corrosion, dampness and contamination. These plastic units use powerful adsorbing agents, either silica gel or molecular sieves, and saturation indi- cators show when reactivation or replacement is required. When the humidity adsorber is dry the saturation indicators are blue, but these turn pink when the maximum amount of moisture has been adsorbed. The silica gel adsorbers can be reacti- vated for re-use by heating them at 100ºC for four hours in a ventilated oven. Brownell
www.brownell.co.uk T: 0208 965 9281 Enter 226
EMC shielding solutions for enclosures
While the first level of EMC shielding is PCB design, the enclosure will usually need some form of EMC shielding in the seams and openings such as doors, windows, ventilation, cable entry, etc. However, as it is difficult to retrofit EMC gasketing and components, EMC for enclosure design needs to be considered in the early stages. Consideration should also be given to the environment the equipment will be used in, as dust and water sealing can be incorporated into the EMC gasket; and galvanic compatibility between materials is an important consideration where a salt laden atmosphere is present.
Large enclosures – ranging from 19” racks and cabi- nets up to shipping container sized communication cabins – tend to need large gaskets to take up the tol-
erances that occur over long lengths such as doors. If the gasket needs to be 10mm high then the width should be no less than this.
Gaskets suitable for such applications are conductive fabric over foam as these are very soft and flexible but only offer electric field shielding and no environmental seal. Where magnetic shielding is required knitted wire mesh or combination gaskets are best suited, and these can be incorporated with environ- mental dust and water seals. Beryllium copper fingers are a good option where very high performance is required, such as shielded room doors, however breakage can occur.
Smaller enclosures – such as those for instrumentation and communication equipment – usually require much smaller profile gaskets. Here, the most cost effective method of providing an EMC and dust/moisture seal is to use an electrically conductive elastomer O ring in a groove. This method can utilise very small profiles down to 1mm diameter section. Where softer gaskets are required a tubular section can be used. Any O ring diameter or developed length is available. If there is insufficient land to put a groove, the gasket can be directly applied to the surface with conductive elastomer form in place. Very complex paths can be applied by this method.
There are many other electrically conductive flat sheet gasket types available, such as oriented wires, woven and expanded metal in elastomers suitable for surface mount applications. To meet requirements, Kemtron offers a complete range of EMC gaskets including EMC ventilation panels, shielded windows, cable glands etc. Kemtron
T: 01376 348115
Configurable enclosure range extended New components have been added
to OKW’s ‘Interface-Terminal’ series, including flush mounted ABS front panels, deeper bottom sections and new low profile wall mounting elements, providing design engineers with an even wider range of possible housing configurations.
The ABS panels are recessed for mounting a membrane keypad or product label, while the deeper bottom sections provide more space for the PCBs, displays and keypads as well as touch screens. The new wall mounting elements can be easily fitted to a wall or machine housing and include a push-button locking mechanism. Five pole contacts can also be mounted to the wall element and case for charging and data transfer when the housing is attached. The main housing components are moulded in off-white ABS and have a contoured shape with external dimensions of 190 x 135 x 95mm (S), 225 x 165 x 104mm (M) and 275 x 195 x 36mm (L). The three-part assembly consists of the top and centre section,
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www.kemtron.co.uk
which can be mounted in a por- trait or landscape orientation on the base section or base panel. The base panel can be specified with a battery compartment for five 1.5V AA cells. The Interface-Terminal range is suitable for applications including medical and wellness equipment, measuring and control instru- ments, security electronics, point- of-sale systems and much more. OKW Enclosures
Enter 228 T: 01489 583858
www.okw.co.uk DIN rail mounted PCB enclosures
A new line of DIN rail mounted PCB enclosures has been intro- duced by Hylec-APL.
The fully customisable hous- ings, from the company’s DE Controls manufacturing divi- sion, are available with solid or open tops in a number of unit sizes. All can be mounted on ‘Top Hat’ DIN rails or surface mounted as standard.
The range consists of two different design styles. The DNMB
(pyramid) design is available in 60mm and 73mm high versions with six length options between 18.5mm and 158.5mm; the DNCB (box) design is 100mm high and available with 36mm, 53.5mm and 71mm lengths. Both the 60mm and 73mm versions are available as one piece solid mouldings for improved structural integrity. All models share a uniform width of 90mm to fit on relevant DIN rails. Ergonomically designed to make them practical to install and aesthetically pleasing, these are manufactured from flame retardant UL94-V0 polycarbonate and have an enclosed and insulated base. They can house up to three PCBs horizontally and up to four PCBs vertically (depending on the model). A screw mounted heat sink can also be incorporated as necessary. The products are designed for snap-fit, easy tool-less assembly, which facilitates quick installation. Ventilated body styles are available as standard with a range of accessories to allow users to further customise the product. Applications and industries including lighting controllers, circuit protection, energy management systems, power supplies and HVAC controls. Hylec APL
Enter 229 T: 01933 234400
www.Hylec-APL.com OCTOBER 2012 Supplement: Enclosures & enclosure furniture
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