The standard “VW PV 3942 Emission behaviour of parts, components and semi-finished products - For vehicle interior”, developed by the Volkswagen automobile company, describes a procedure for determining the amount of organic chemical substances released by parts used in the vehicle interior under the described conditions.
This standard describes a test chamber method for determining volatile organic emissions from parts, components or semi-finished products of the vehicle interior. This standard includes requirements for a test chamber with a volume of 1 m3 used to perform emission tests. It also describes the emission test procedure from the preparation of the device under test to the end of the measurement of the chamber used for this purpose.
To verify that the material requirements are met, test results may be determined by test institutes accepted by the Volkswagen Group for this standard.
A test vehicle is placed in an approximately ideally mixed test area of known and precisely defined volume and maintained at a specified temperature, humidity and air exchange. Organic matter escaping from the test vehicle accumulates in the test area and is drawn off by an air flow.
At certain time points, air samples are taken from the test room and the concentrations of gaseous air components are determined by gas chromatography/mass spectrometry (GC MS) overview analysis. In addition, an odor test is performed, the odor assessment is carried out in accordance with the PV 3900 standard.
The overall concentration of organic compounds in the tested vehicle chamber is continuously recorded by means of a flame ionization detector throughout the entire test period. For more comprehensive analysis, there is the option of taking additional air samples to analyze specific groups of substances.
A test bed used to determine gas emissions consists of:
Open-loop and closed-loop control equipment is required for:
There are no specifications regarding the type, arrangement, combination or technical design of these individual functional elements. The minimum requirements to be met are listed in other sections. In addition, it is necessary to verify (e.g. by sequential testing) that the specific emission test bed can be used to obtain comparable results for the chemical substances to be determined. Notes on ongoing quality assurance measures are described in another section.
The test vehicle room is a hermetically sealed room with a volume of, for example, 1 plus/minus 0,05 m3. Different test area sizes are possible but must be specified. The interior of the test room contains air mixing equipment and a shelf to support the tested vehicle without contact with any of the walls. There must be an inlet and an outlet pipe (each with a maximum diameter of 50 mm) for regulating air exchange and air sampling. This room must be arranged crosswise to prevent short-circuiting flows.
The test area wall surfaces and the rack used to support the tested instrument shall be constructed of stainless steel or glass. For fixtures or components within the test area where neither of the two specified materials can be used for technical reasons, materials with the lowest possible organic matter emission and absorption shall be selected. If these components are in contact with the test area atmosphere, the sum of their surface areas shall not exceed 5 percent of the test area wall surface area.
To prevent unregulated air exchange processes, it should be ensured that the leakage flow due to leaks in tests with active air exchange at 1 000 Pa positive pressure is less than 0,5 percent of the test area volume per minute or 5 percent of the supply air flow. To prevent external supply air flow, emission tests should be carried out with a slight positive pressure in the test area or with excessive volumetric flow relative to atmospheric pressure in the laboratory. This should be ensured especially during air sampling.
An important basis for this method is the intended ideal mixing of air in the test area. This must be ensured by means of suitable air mixing equipment so that this prerequisite can be met even when testing large volume, bulky test vehicles. The air flow velocity should be at least 0,1 m/s in the centre of the empty test area.
Thorough cleaning should be performed using a suitable cleaning method (e.g. thermal desorption at elevated temperatures). The success of the cleaning should be verified with a blank sample before testing begins.
Due to the high dependence of the emission behavior on the test temperature, the spatial and temporal temperature deviation for the test area should not exceed a tolerance of plus/minus 1 degree.
Humidification of the test room supply air should be carried out in a way that prevents the formation of vapor and aerosol. The humidification unit should allow a relative humidity of 65 percent in the supply air flow at 5 degrees.
Among the numerous tests, measurements, analyses and evaluations carried out for businesses in various sectors, our organization also provides testing services defined in the standard “VW PV 3942 Emission behavior of parts, components and semi-finished products - For vehicle interiors” with its trained and expert staff and advanced technological equipment.
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