As a valued partner to the automotive industry, Benecke-Kaliko is committed to innovative and sustainable products. One important issue in this regard relates to the lowest possible emissions in a vehicle's interior which can be measured with different methods. When the requirement is to determine both the VOC emissions and the aldehyde/ketone emissions from the plastic materials in a vehicle, the Asian automotive industry in particular very often resorts to bag methods. That is because, compared with the VDA method, the bag method is less expensive since the test equipment - the bags and the oven - are significantly cheaper than the test cabinet for VDA 276.

Whereas, for example, the German Association of the Automotive Industry (VDA) test requires the pollutant concentrations to be measured in a test cabinet, in Asia the samples are usually packaged in bags and then heated in an oven. The pollutant concentration in the bag is then measured. However, it is difficult to obtain comparable test results because all the car makers have their own individual test specifications for the bag method, which differ to a greater or lesser extent from the ISO 12219-2 standard.

Benecke-Kaliko has analyzed the different specifications with regard to their influence on the result. This involved specifically varying test conditions such as sample preconditioning, oven temperature, oven dwell time, sample size and fill volume of the test bag. "In the main, the same qualitative results are obtained, i.e. the same substances are identified," says Dr. Roland Freudenmann, Global Head of Laboratories at Benecke-Kaliko, summarizing the results. However, the situation is different when it comes to the quantitative results, i.e. the pollutant concentration: These results vary greatly, depending on the different test conditions.

Benecke-Kaliko's analysis showed that the preparation of the samples has the biggest influence. "The divergence here can be as much as 2,000 percent," emphasizes Freudenmann. The second parameter which has a highly significant effect on the result is the oven temperature. "The VOC emissions rise by 1,000 percent and the aldehyde emissions by 300 percent if an oven temperature of 80°C is specified instead of 60°C," says Freudenmann.

The tempering period of, for instance, two hours also has to be accurately observed, he added, because the emissions results change substantially with varying times. "A variation from oven to oven with different heating characteristics is therefore also to be expected," Freudenmann concludes. Changes in the fill volume and different removal rates had little or no effect in Benecke-Kaliko's labs: "Increasing the sample size from 8 cm by 10 cm to 10 cm by 10 cm has only a minor effect on the quantitative difference in emissions."

Although sample conditioning has the greatest influence on the measurement result with the bag method, it is not defined at all or is only approximately defined in some specifications. "But without a definition as in the VDA 278 method - "Seal promptly after production, condition at room temperature in the test institute for seven days, then test" - very sizable scatter is to be expected with all the bag methods. A common specification of, for example, seven days at room temperature would therefore be an important prerequisite for obtaining reproducible results," is Freudenmann's verdict.

Now that an appropriate test configuration has been developed and key factors defined, Benecke-Kaliko is able to help its Asian customers achieve meaningful results. In addition, Benecke-Kaliko is able to enhance the air quality in automotive interiors thanks to its innovative products such as the low-emission Acella Eco.