Method for measurement of thermal decomposition products of sand cores bonded with polyurethane in foundries

Status:

completed 04/2003

Aims:

Indicative measurements of hazardous substances performed in foundries and pilot plant trials provided clear evidence of the release of aniline, phenyl isocyanate, aldehydes, aromatic amines, phenols, and other crack products during cold-box casting. To date, documented results in this area have been scarce; further data were therefore required. In addition, a need existed for the available standard measurement methods (in particular for isocyanates and aromatic amines) to be adapted for the extreme ambient conditions of liquid metal casting and also developed further for certain new substances.

Activities/Methods:

The first step carried out by the BG Institute for Occupational Safety and Health (BIA) entailed development of a measurement method for determining the atmospheric concentration of the following aromatic amines under the specific conditions encountered at foundry workplaces employing the cold-box method: aniline, o-toluidine, p-toluidine, 2,4-dimethylaniline, 2,6-dimethylaniline, 4,4'-diaminodiphenylmethane. XAD-7 was employed for sampling. Following desorption with toluene and derivatization with heptafluorobutyric acid anhydride, the amines were measured by gas chromatography with ECD detection. The detection limits were 5 µg/m³ for a sampling duration of two hours for all amines stated. Following validation in the laboratory, the procedure was tested under practical conditions in an aluminium foundry.

Results:

A method was developed for measurement of exposure to aromatic amines at cold-box casting workplaces. The procedure satisfies the requirements of DIN EN 482, "General requirements for the performance of procedures for the measurement of chemical agents", and can be applied with immediate effect as a standard procedure within the scope of the BGMG hazardous substances measurement system. A standard instruction procedure is currently being drawn up. A follow-up project is planned which will systematically assess exposure to aromatic amines in workplaces in a range of foundries.

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