Measurement method for determination of not water miscible metal working fluids and other complex mixtures containing carbohydrates at workplaces

Status:

completed 12/2012

Aims:

Cooling lubricants and complex mixtures containing hydrocarbons are products containing mineral oils and additives that are employed in manufacturing, for example during the machining of metals or as release agents for prefabricated concrete parts. The composition of these substances varies according to their intended use. Owing to the diversity of the additives, it has proved effective to gear measurement of the substances in workplace atmospheres to the mineral oils forming their primary components, and to use infrared spectrometry for the purpose of analysis. Depending upon the physical properties of the various mineral oil fractions and their use at the workplace, they may occur simultaneously in vapour and aerosol form. Sampling must therefore consider both phases. A need arose for the IFA test method developed approximately 20 years ago to be thoroughly revised and to be fully validated in consideration of the latest standards.

Activities/Methods:

Sampling was performed by means of the GSP method in its GGP configuration for aerosol/vapour sampling. The aerosols were separated on a glassfibre filter, the vapours on XAD-2 adsorber resin. Infrared spectrometry was employed for analysis. During validation of the method, four representative water-immiscible cooling lubricants and other complex water-immiscible mixtures containing hydrocarbons were selected which cover the entire user spectrum. The complete validation process was performed for all four selected products in accordance with EN 482, "Workplace atmospheres – General requirements for the performance of procedures for the measurement of chemical agents", EN 1076, "Workplace exposure – Procedures for measuring gases and vapours using pumped samplers – Requirements and test methods", and the new prEN 13936, "Workplace exposure – Procedures for measuring a chemical agent present as a mixture of airborne particles and vapour – requirements and test methods". Besides the statistical data (expanded uncertainty of measurement, recovery rates for various concentrations, storability of the coated sampling media, limits of detection), the distributions of the different mineral oil products between the vapour and aerosol phases were also determined. Following completion of the work, standard work instructions were formulated.

Results:

The method was completely revised. It satisfies the basic requirements governing measurement methods in accordance with EN 482 and prEN 13936 for all four complex mixtures containing hydrocarbons. In the studies of the distribution of aerosols and vapours as a function of the sampling conditions, it was clearly evident that separate sampling of the aerosols and vapours is not possible. Since the system is dynamic, numerous variables such as the droplet size, room temperature, flow rate and sampling duration have an influence upon the respective proportions; only the sum of the vapour and aerosol is constant.

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