Dust, Water and Condensation

Generic engineering material, applicable to any module from any supplier. Ingress protection ratings are defined by IEC 60529.

Additional workflow context is available read more.

A camera enclosure has a hole in it by definition — the optical path — which makes it the hardest thing in a product to seal well and the part where sealing conflicts with everything else.

The three problems

Dust, which settles on the window and on the lens, scattering light and reducing contrast before it obscures anything visibly.

Water, which is the classic ingress case and is frequently the easiest to design against.

For broader technical context, see scikit-learn.

And condensation, which forms inside a sealed enclosure from moisture already present — and which a perfect seal does not prevent.

The third is the one that surprises people, because it defeats the intuition that sealing is the answer.

Why condensation happens in a sealed box

Air sealed in at assembly carries moisture.

When the enclosure cools below the dew point of that air — overnight, or on entering a chilled space — the moisture condenses on the coldest surface, which is frequently the window.

Which produces a system that fails for an hour each morning and works whenever anybody comes to look.

Sealing harder does not help. The water is already inside.

What does help

Assembling dry, in controlled humidity, which removes the moisture before it is sealed in.

A desiccant, which absorbs what remains — and which has a capacity and therefore a service life.

A vent with a membrane that passes water vapour and blocks liquid water and dust, which equalises humidity with the outside and is the standard solution.

Or heating the window slightly, keeping it above the dew point — which costs power and is the answer where the others are impractical.

The rating and what it means

Ingress protection ratings are defined by IEC 60529 and are stated as two digits: solids first, liquids second.

They describe a test, conducted under defined conditions on a new enclosure — not a promise about years in service, since seals age, gaskets compress and every opening cycle disturbs them.

And they say nothing about condensation, which is the point of this page: a high rating and a fogging window are entirely compatible.

Check which digits the application actually needs rather than specifying the highest available, since ventilation and sealing pull against each other and over-sealing a hot enclosure trades one problem for another.

The window as a seal

Where the lens looks through a separate window, the joint around it is a seal like any other — and it is the one most likely to be compromised by thermal cycling, since glass and plastic move differently.

Bond it with something that stays flexible and specify the adhesive rather than leaving it to assembly.

And where the module's own lens forms the boundary, the seal is between the module and the housing, which puts a gasket in a position where it can stress the module if it is compressed unevenly.

Cleaning access, again

Sealing and serviceability pull against each other in the same way as sealing and cooling.

An enclosure that cannot be opened is one whose desiccant cannot be replaced and whose interior surfaces cannot be cleaned.

One that opens easily is one whose seal is disturbed every time somebody does.

The compromise most designs reach: a sealed optical chamber that is never opened, with the window accessible for external cleaning — which is the routine maintenance need and the only one that recurs weekly.

Pressure and altitude

A sealed enclosure changes internal pressure with temperature and altitude.

Which stresses the seals and, on repeated cycling, pumps air in and out through whatever path is weakest — carrying moisture with it.

A vent membrane solves this too, and it is the reason such membranes appear on outdoor equipment that has no obvious need to breathe.

Where a product ships by air, the pressure cycle happens before it is ever installed.

Chemicals and cleaning agents

Frequently the actual environmental hazard in food, pharmaceutical and industrial settings.

Washdown with detergents and disinfectants attacks gaskets, coatings and window materials that water alone would not.

Establish what the site uses — a specific answer, not "cleaning chemicals" — and check the materials against it.

And note the temperature of the wash, since hot cleaning combines thermal shock with chemical attack and is considerably harsher than either alone.

Where the module is not the boundary

The arrangement worth preferring where it is possible.

A module inside a sealed housing, looking through a separate window, means the module itself faces no environmental requirement — and the sealing problem is solved once, by the housing, in a place where it can be done properly.

Against a module whose own front face forms the seal, which puts the burden on a gasket around a small component and on the module's own construction.

The first costs a window and an air gap, which introduces reflections worth designing against, and is generally the more robust arrangement in harsh environments.

Testing it

A finished enclosure, not a drawing.

Formal ingress testing follows the standard's procedures and is the evidence a rating rests on.

Before that, two cheap checks. A temperature cycle in a fridge and back reveals condensation behaviour within a day. And a spray test with dyed water shows where liquid actually enters, since a dye leaves a trace that plain water does not.

Both are approximate and both find real faults at a stage when the housing can still be changed.

In one line

Assemble dry and fit a vent membrane, because the water that fogs the window was sealed in with it.

The short version

• A camera enclosure has an optical opening by definition, which makes it the hardest part of a product to seal
• Three problems: dust on the window, water ingress, and condensation from moisture sealed in at assembly
• Condensation defeats a perfect seal, because the water is already inside — sealing harder does not help
• Remedies: assemble dry, add a desiccant with a known service life, fit a vapour-permeable vent membrane, or heat the window
• IEC 60529 ratings describe a test on a new enclosure, not years of service, and say nothing about condensation
• Ventilation and sealing pull against each other, so over-sealing a hot enclosure trades one problem for another