Textual Amendments
In addition to the linearity requirements defined for each analyser in point 3, the compliance of analyser types with the specifications laid down in points 4.2.2 to 4.2.8 shall be demonstrated by the analyser manufacturer. Analysers shall have a measuring range and response time appropriate to measure with adequate accuracy the concentrations of the exhaust gas components at the applicable emissions standard under transient and steady state conditions. The sensitivity of the analysers to shocks, vibration, aging, variability in temperature and air pressure as well as electromagnetic interferences and other impacts related to vehicle and analyser operation shall be limited as far as possible.
The accuracy, defined as the deviation of the analyser reading from the reference value, shall not exceed 2 % of reading or 0,3 % of full scale, whichever is larger.
The precision, defined as 2,5 times the standard deviation of 10 repetitive responses to a given calibration or span gas, shall be no greater than 1 % of the full scale concentration for a measurement range equal or above 155 ppm (or ppmC 1 ) and 2 % of the full scale concentration for a measurement range of below 155 ppm (or ppmC 1 ).
The noise, defined as two times the root mean square of ten standard deviations, each calculated from the zero responses measured at a constant recording frequency of at least 1,0 Hz during a period of 30 seconds, shall not exceed 2 % of full scale. Each of the 10 measurement periods shall be interspersed with an interval of 30 seconds in which the analyser is exposed to an appropriate span gas. Before each sampling period and before each span period, sufficient time shall be given to purge the analyser and the sampling lines.
The drift of the zero response, defined as the mean response to a zero gas during a time interval of at least 30 seconds, shall comply with the specifications given in Table 2.
The drift of the span response, defined as the mean response to a span gas during a time interval of at least 30 seconds, shall comply with the specifications given in Table 2.
Permissible zero and span response drift of analysers for measuring gaseous components under laboratory conditions
| Pollutant | Zero response drift | Span response drift |
|---|---|---|
| CO 2 | ≤ 1 000 ppm over 4 h | ≤ 2 % of reading or ≤ 1 000 ppm over 4 h, whichever is larger |
| CO | ≤ 50 ppm over 4 h | ≤ 2 % of reading or ≤ 50 ppm over 4 h, whichever is larger |
| NO 2 | ≤ 5 ppm over 4 h | ≤ 2 % of reading or ≤ 5 ppm over 4 h, whichever is larger |
| NO/NO X | ≤ 5 ppm over 4 h | ≤ 2 % of reading or 5 ppm over 4h, whichever is larger |
| CH 4 | ≤ 10 ppmC 1 | ≤ 2 % of reading or ≤ 10 ppmC 1 over 4 h, whichever is larger |
| THC | ≤ 10 ppmC 1 | ≤ 2 % of reading or ≤ 10 ppmC 1 over 4 h, whichever is larger |
Rise time is defined as the time between the 10 per cent and 90 per cent response of the final reading ( t 90 – t 10 ; see point 4.4). The rise time of PEMS analysers shall not exceed 3 seconds.
Exhaust gases may be measured wet or dry. A gas-drying device, if used, shall have a minimal effect on the composition of the measured gases. Chemical dryers are not permitted.]