Electronics Protection - Summer 2017 - 14

Feature
Holland continued from page 13

58. Conductive foam is an open structure so it is not watertight, but it can be combined with a watertight neoprene gasket.
59. Knitted mesh for military and low-frequency use is available made out of full metal (10 to 15 percent compression) neoprene foam covered with knitted metal wires that has 30 to 40 percent compression. Silicone tube covered
with knitting has up to 50 percent compression and low compression force.
60. The knitted-mesh gasket can be mounted into a groove or can be produced with a fin so that it can be screwed
or clamped.
61. When there is no groove in your construction, the knitted wire mesh gasket can be glued to self-adhesive rubber,
to keep it in place.
62. For high-performance gaskets to seal gaps in for example Faraday cages for sensitive measurement the gaskets
can be produced in a double implementation and bolted in the center.

Ventilation Panels

63. Within a few days we can produce Honeycomb ventilation panels according to the customer's drawing. The honeycomb structure is like waveguides and lets air though while blocking electromagnetic waves from entering.
The cell size of the honeycombs is 3.2 mm and combinations of sever layers is possible, even under cross constructions for higher performance. A cross cell honeycomb consists of minimal two layers of Honeycomb material
stepped and rotated 90 degrees relative to each other. This results in a good shielding performance independent of
the polarization of the waves (Fig. 23).
64. The prevent from dust, a dust
filter can be integrated in the ventilation panel. The dust filter can
also be mounted to the outside of
the of the enclosure (Fig. 24)
65. The standard cost-effective
honeycomb is made of aluminium,
but for special applications like
EMP it can also be made out of
mild steel, which is more expensive.

Figure 23. (left) Example of a cross-cell honeycomb venitilation panel
Figure 24. (top right) From left to right, honeycomb with dust filter, cross cell, single cell,
straight cell slant 45°, double slant to prevent eavesdropping
Figure 25. (bottom right) Dawing of a frameless honeycomb construction

66. A honeycomb ventilation panel
can be framed and pre drilled on
request for easy mounting or can
be produced frameless with optional a pressed flange for smaller constructions or when the Honeycomb ventilation
panel is mounted in a clamped construction.
67. For outdoor use the honeycomb can be treated with a nickel or other finish. This is to protect the Honeycomb
ventilation panel from environmental influences such as corrosion.
68. To keep raindrops from falling into the enclosure we can make the honeycomb also at a slant (45° is standard).
69. Two layers of slanted honeycomb placed opposite to one another also make it impossible for metal rods to be
entered into the cage, and thus prevent from electrocution (Fig. 23).

70. Mounting framed honeycombs can be done via through holes or threaded holes which are flow drilled into the
frame in order to achieve a good screw length. Flow drilling is better than using rivets, which may become loosened.
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Table of Contents for the Digital Edition of Electronics Protection - Summer 2017