Far away from protected server rooms or automation lines in air-conditioned production halls, embedded computers need to withstand the toughest conditions in modern vehicles and moving machines, or in outdoor installations such as railway lines. This presentation answers questions on how to develop sealed enclosures according to the required IP classes, which materials should be selected and in which applications these requirements are particularly important.

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February 1, 2018
5 Things to Know about
IP Classes in Rugged Computing

2. 2
Batten Down the Hatches
Far away from protected server rooms or automation lines in air-conditioned
production halls, embedded computers need to withstand the toughest
conditions in modern vehicles and moving machines, or in outdoor installations
such as railway lines.
This presentation answers questions on how to develop sealed enclosures
according to the required IP classes, which materials should be selected and in
which applications these requirements are particularly important.
1: What are common IP classes in embedded?
2: How to realize sealed housings?
3: Which role does the right connector play?
4: Is the housing completely airtight even in the highest IP class?
5: Where does the waste heat go?

3. What are Common IP Classes in Embedded?
IP classes are always made up of two
digits. The first stands for protection
against foreign bodies (such as dust) and
solids; the second stands for protection
against liquids. Typical examples for
embedded requirements are:
▪ IP54 – boxes or panel PCs for all outdoor
applications
▪ IP65 – box PCs or panel PCs for railways,
modules for medical
▪ IP67 – extremely rugged applications,
like mining machines, agriculture vehicle
with chemical influences…
Higher IP classes can be achieved by
casting the entire housing – except for a
cover with connector plugs – from a
single mold.
Dust Liquids
0 No protection
0 No protection
1 Solid object greater than
50mm (hand) 1 Vertically falling drops of water
(e.g. condesation)
2 Solid object greater than
12,5mm (finger) 2 Direct sprays of water up to 15
degrees from vertical
3 Solid object greater than
2,5mm 3 Direct sprays of water up to 60
degrees from vertical
4 Solid object greater than
1mm 4 Water sprayed from all
directions, limited ingress
5 Dust protected, limited
ingress of dust 5 Low-pressure jets of water
from all directions, limited
ingress
6 Dust tight, zero ingress of
dust 6 Strong jety of water from all
directions, limited ingress (e.g.
ship‘s deck)
7 Temporary immersion
between 15cm and 1m
8 Long period of immersion
under pressure
9 High pressure, high
temperature jets of water
from multiple directions

4. How to Achieve Sealed Housings?
▪ To achieve i.e. IP65 class with complete protection against dust ingress and
protection against water jets, a 8 mm-thick aluminum housing (a wall thickness
of 2 mm suffices for standard box PCs) is recommended, which seals the PC on
all sides with screws and silicone-filled contours. The thickness of the housing
walls and the number and position of the screw fittings determine the contact
pressure that can later be applied to the housing without the contact on the
touch points and therefore the impermeability being lost.
▪ EMC protection can be achieved through conductive silicone material with
silver particles.

5. lhhWhich Role Does the Right Connector Play?
▪ For all interfaces used, the plug connection, along with the connecting
cables themselves, must be sealed in such a way that it also conforms to the
IP class.
▪ Typical industrial interface connectors such as USB, DisplayPort or RJ45 are
available in many sealing classes – but cost up to 10 times more than usual
robust connectors for harsh environments
▪ This usually results in M12 connectors, which can be sealed up to IP76 and
even work reliably under severe impacts and vibrations
▪ The pin assignment must be defined
by the manufacturer. Also the
appropriate adapter cables need to
be well chosen (e.g. due to the high
speed of USB 3.0, cables should
contain twisted pairs)

6. Is the Housing Completely Airtight Even in the
Highest IP Class?
Even if the required protection class is achieved by means of the later contact
pressure and surrounding seals on all points of contact, the box will still never be
completely airtight. This is a decisive criterion in which pressure compensation
plays a key role.
Due to thermal expansion and contraction of the materials caused by
temperature fluctuations (or equally by altitude differences in aviation), small
amounts of air would be sucked in through the seals, thus bringing moisture into
the interior of the housing from where it can no longer escape.
To prevent this, a pressure compensation
valve can be installed on the rear of the
housing. This ventilates the housing just
enough to allow condensation to be kept
to a minimum.

7. Where Does the Waste Heat Go?
Tightly sealed embedded systems inevitably raise the issue of heat dissipation. If
there is merely a small valve ensuring pressure compensation – and thus virtually
no air circulation – how can the electronics be cooled? The solution is conduction
cooling, which is also the reason why a heat-conducting aluminum housing is
used in all robust designs.
For this reason, it is essential that components that produce heat are thermally
connected to the housing, as a result the device itself becomes the heat sink. This
technology is not limited to box PCs – it can also be implemented with 19"
components (CompactPCI / CompactPCI Serial) or COM Express modules (Rugged
COM Express).
➢ Read the full article about IP classes in
rugged computing
➢ Check out our rugged product range

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www.menmicro.com/competencies/rugged-computing/
www.men-france.fr/competencies/rugged-computing/