Document ID: chunk:federal_register_of_legislation:F2023L00129:reg:13:p15
Version: federal_register_of_legislation:F2023L00129
Segment Type: reg
Provision Reference: reg 13 (pt 15/56)
Character Range: 336337–339301

sample proportional to the exhaust mass flow rate. The quality of proportionality shall be checked by applying a regression analysis between sample and exhaust flow in accordance with paragraph 9.4.6.1. The complete test set up is schematically shown in Figure 6.
           Figure 6
           Scheme of raw/partial flow measurement system
8.4.1. Determination of exhaust gas mass flow
8.4.1.1. Introduction
 For calculation of the emissions in the raw exhaust gas and for controlling of a partial flow dilution system, it is necessary to know the exhaust gas mass flow rate. For the determination of the exhaust mass flow rate, one of the methods described in paragraphs 8.4.1.3. to 8.4.1.7. may be used.
8.4.1.2. Response time
 For the purpose of emissions calculation, the response time of any of the methods described in paragraphs 8.4.1.3. to 8.4.1.7. shall be equal to or less than the analyzer response time of  ≤  10 seconds, as required in paragraph 9.3.5.
 For the purpose of controlling of a partial flow dilution system, a faster response is required. For partial flow dilution systems with online control, the response time shall be ≤  0.3 second. For partial flow dilution systems with look ahead control based on a pre-recorded test run, the response time of the exhaust flow measurement system shall be ≤  5 seconds with a rise time of ≤  1 second. The system response time shall be specified by the instrument manufacturer. The combined response time requirements for the exhaust gas flow and partial flow dilution system are indicated in paragraph 9.4.6.1.
8.4.1.3. Direct measurement method
 Direct measurement of the instantaneous exhaust flow shall be done by systems, such as:
(a) Pressure differential devices, like flow nozzle, (details see ISO 5167);
(b) Ultrasonic flowmeter;
(c) Vortex flowmeter.
 Precautions shall be taken to avoid measurement errors which will impact emission value errors. Such precautions include the careful installation of the device in the engine exhaust system according to the instrument manufacturers' recommendations and to good engineering practice. Especially, engine performance and emissions shall not be affected by the installation of the device.
 The flowmeters shall meet the linearity requirements of paragraph 9.2.
8.4.1.4. Air and fuel measurement method
 This involves measurement of the airflow and the fuel flow with suitable flowmeters. The calculation of the instantaneous exhaust gas flow shall be as follows:
 qmew,i  = qmaw,i + qmf,i (28)
 Where:
                  qmew,i is the instantaneous exhaust mass flow rate, kg/s
                  qmaw,i is the instantaneous intake air mass flow rate, kg/s
                  qmf,i is the instantaneous fuel mass flow rate, kg/s
 The flowmeters shall meet the linearity requirements of paragraph 9.2., but shall be accurate enough to also meet the linearity requirements for the exhaust gas flow.
8.4.1.5. Tracer measurement method
 This involves