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20.04.2023
Tamper-Proof Exhaust Emission Tests
For valid soot particle measurements: Portable calibrating system for measuring instruments in accordance with the new Euro 6/VI emission standards
Until now, it has been impossible to determine whether a diesel particulate filter was working – or had been installed at all – from the data collected during exhaust gas measurement using the turbidity measurement process. The solution is particle counting.
The introduction of particle measuring as a new emission test method for Euro 6/VI diesel vehicles closes an important information gap in terms of measurement data.
Scale MT, a company based in Regensburg, Germany, has developed a calibration method for particle measuring devices and successfully launched it in European countries. The particle calibrating system comprises a combination of KNF pumps, consisting of a compressor and a micro gas pump.
Deficient diesel particulate filters go undetected
So far, turbidity measurement with an opacimeter has been the method of choice for determining whether emission limits were being met.
This optical analysis has one significant disadvantage: The measuring data does not indicate whether the diesel particulate filter is operating in accordance with prevailing standards. The data does not even indicate whether or not a diesel particulate filter is installed at all.
However, this gap has been closed with the introduction of a new mandatory particulate measurement method as part of Euro 6/VI for diesel vehicles to measure emissions.
Calibration of the exhaust gas analyzers for motor vehicles according to the Euro 6/VI guideline
The more conclusive method of particle counting also requires the exhaust gas measurement devices to be regularly calibrated.
The German calibration directive for exhaust gas analyzers currently requires them to be tested every 12 months as well as after any intervention in the measurement data acquisition, e.g., due to an adjustment as part of the annual maintenance.
Certified service providers or technicians trained through a certification scheme may carry out such tests and issue valid calibration certificates.
In Germany, an authorized emission test during vehicle inspection must use a calibrated particle counter accredited by DakkS, the German accreditation body.
Car owners in Germany will receive a new TÜV certificate once the exhaust gas test confirms that the emission limit values have not been exceeded in the vehicle inspection.
Portable calibration systems with internal compressed air to be used all across Europe
Scale MT’s calibration system has been approved by the Physikalisch-Technische Bundesanstalt, the relevant authority in Germany. The system was developed for particle counters that work according to the condensation particle counter (CPC) principle.
The company from Regensburg, Germany specializes in particle measurement technology and has years of experience in the automotive industry. Scale MT relies on KNF’s robust pumps for a reliable process flow in the calibration line of the PKS 100 E system.
In several European countries, calibration service providers already put their trust in the reliability of this system.
The Scale MT PKS 100 E combines the functions of generating, guiding and measuring test aerosols as well as validating the particle counter.
Scale MT’s portable calibrating system PKS 100 E is used for testing particle counters as part of vehicles’ periodical technical inspection in several European countries. Photo credit: © Scale MT GmbH
Test aerosols for condensation particle counters for vehicles’ periodical technical inspection
Test aerosols cannot be stored. Therefore, each calibration begins with generating the test aerosol. For this purpose, a sodium chloride solution is vaporized by a nozzle. The shearing force in the gas volume flow takes droplets with it, creating condensation nuclei which are turned into stable, homogeneous particles as they are guided through the system, with a defined size in the nanometer range.
Calibration is completed when the measurement of the test aerosol is compared with the test device and the reference instrument.
KNF compressor and gas pump for calibration
The clean compressed air required for vaporizing the saline solution is generated by the oil-free operated KNF compressor NPK 09.1.2. Even though it has a high performance of up to 7 bar rel., the compressor is a lightweight, which makes the system portable.
Guiding the generated condensation nuclei through the system to the measurement point is critical for meeting the specifications set forth in the calibration guideline for test aerosols. Only homogeneous, stable salt crystals meet the requirements for a valid test.
A KNF NMP 850.1.2 HP series micro gas pump reliably fulfills this task. Even dried salt crystals do not affect its functioning.
The oil-free operating KNF compressor NPK 09.1.2 generates compressed air required for the dispersion of the sodium chloride solution and thus for the formation of a condensation nucleus.
The KNF NMP 850.1.2 HP micro gas pump produces a vacuum that safely guides the test aerosols in nitrous acid to the measuring point.
Supply chain disruptions delay particle measurements
In Germany, particle counting will be obligatory for Euro 6/VI diesel vehicles from the beginning of 2023. At least in theory. In reality, implementation is stagnating, as the producers of measuring instruments are missing parts – due to global disruptions affecting supply chains. Implementation has been postponed to July 1, 2023 at the latest.
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