Document ID: chunk:federal_register_of_legislation:F2023L00129:reg:13:p21
Version: federal_register_of_legislation:F2023L00129
Segment Type: reg
Provision Reference: reg 13 (pt 21/56)
Character Range: 354083–356782

a system without flow compensation, the ratio of sample flow to CVS flow shall not vary by more than ±2.5 per cent from the set point of the test. For a system with flow compensation, each individual flow rate shall be constant within ±2.5 per cent of its respective target flow rate.
 The complete test set up is schematically shown in Figure 7.
    Figure 7
    Scheme of full flow measurement system
8.5.1. Determination of the diluted exhaust gas flow
8.5.1.1. Introduction
 For calculation of the emissions in the diluted exhaust gas, it is necessary to know the diluted exhaust gas mass flow rate. The total diluted exhaust gas flow over the cycle (kg/test) shall be calculated from the measurement values over the cycle and the corresponding calibration data of the flow measurement device (V0 for PDP, KV for CFV, Cd for SSV) by one of the methods described in paragraphs 8.5.1.2. to 8.5.1.4. If the total sample flow of particulates (msep) exceeds 0.5 per cent of the total CVS flow (med), the CVS flow shall be corrected for msep or the particulate sample flow shall be returned to the CVS prior to the flow measuring device.
8.5.1.2. PDP-CVS system
 The calculation of the mass flow over the cycle is as follows, if the temperature of the diluted exhaust is kept within ±6 K over the cycle by using a heat exchanger:
 (49)
 Where:
                  V0 is the volume of gas pumped per revolution under test conditions, m³/rev
                  nP is the total revolutions of pump per test
                  pp is the absolute pressure at pump inlet, kPa
                  T is the average temperature of the diluted exhaust gas at pump inlet, K
 If a system with flow compensation is used (i.e. without heat exchanger), the instantaneous mass emissions shall be calculated and integrated over the cycle. In this case, the instantaneous mass of the diluted exhaust gas shall be calculated as follows:
med,i = 1.293 x V0 x nP,i x pp  x 273 / (101.3 x T) (50)
 Where:
                  nP,i is the total revolutions of pump per time interval
8.5.1.3. CFV-CVS system
 The calculation of the mass flow over the cycle is as follows, if the temperature of the diluted exhaust is kept within ±11 K over the cycle by using a heat exchanger:
med = 1.293 x t x Kv x pp / T 0.5 (51)
 Where:
                  t is the cycle time, s
                  KV is the calibration coefficient of the critical flow venturi for standard conditions,
                  pp is the absolute pressure at venturi inlet, kPa
                  T is the absolute temperature at venturi inlet, K
 If a system with flow compensation is used (i.e. without heat exchanger), the instantaneous mass emissions shall be calculated