Chamber Volume for IEC 60068-2-1 Tests

Buying a temperature chamber by volume alone is the most common specification mistake we see. The number on the datasheet describes the internal space — not the space your samples can actually occupy.

The working volume rule

Air has to circulate around the load for the chamber to hold uniformity. As a rule of thumb, the samples should not fill more than one third of the internal volume, and they should not touch the walls or block the air path. A 225 L chamber therefore carries roughly 70 L of product, not 225 L.

Temperature range and rate

IEC 60068-2-1 (cold) and 60068-2-2 (dry heat) define the test severities, but the chamber must also be able to reach setpoint and soak within the tolerance band. A chamber specified to −70 °C that takes 90 minutes to get there is a different machine from one that reaches it in 30 minutes at the same load.

Humidity is a separate decision

Damp-heat testing (IEC 60068-2-78) needs a water system, a humidity sensor and a drain, and it constrains where the chamber can be installed. Decide whether humidity is in scope before the room is laid out, not after.

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