The test method specified applies to gas-filled insulating glazing units ('glazing units', for short) as specified in DIN 1259 Part 2 and to multiple glazing units with panes made of organic materials. It serves to provide proof that the improvement in thermal insulation and sound insulation attainable by means of the gas filling as opposed to air is not offset as a result of gas leakage over a period of time. For metrological reasons, the method only applies to glazing units with a percentage by volume per gaseous constituent exceeding 15%. Measuring the tightness of glazing units is not so simple that an operator can be reasonably expected to obtain correct results using the standard, without having any special knowledge.

DIN EN 1279-3 (2003-05)