4.1 This test method is intended to provide a means for determining the concentration of argon, oxygen, and nitrogen gases in individual sealed insulating glass units, which were intended to be filled with a specific concentration of argon at the time of manufacture.

4.2 The argon, oxygen, and nitrogen are physically separated by gas chromatography and compared to corresponding components separated under similar conditions from a reference standard mixture or mixtures of known composition.

4.3 The composition of the sample is calculated from the chromatogram by comparing the area under the curve of each component with the area under the curve of the corresponding component on the reference standard chromatogram.

4.4 It is essential that the person or persons performing this test are very knowledgeable about the principles and techniques of gas chromatography, operation and calibration of gas chromatographs. More information can be found in Practice E355.

4.5 It takes time for the fill gas to equilibrate in any insulating glass unit. This is particularly important in insulating glass units using a tubular spacer and in units containing interior components such as tubular muntin bars. Performing this test before a unit has equilibrated could result in fill gas concentrations that are measurably different than the actual fill gas concentration.

4.6 This method may be used to determine the initial argon gas concentration achieved by the filling method, or the argon gas concentration in units which have been in service or which have been subjected to durability tests such as those described in Test Methods E773 and E2188.

4.7 This method is not applicable to units filled with mixtures of argon and gases other than air.

4.8 This is a destructive test method in that the edge seal of the insulating glass unit is breached in order to obtain a gas sample for analysis by gas chromatography.

4.9 The argon concentration in the gas fill is part of the information necessary to estimate the thermal performance of the sealed insulating glass unit.

Note 1-Other data necessary include gap width, glass thickness, coating type, film coefficients, and so forth, but are beyond the scope of this standard.