Document ID: chunk:federal_register_of_legislation:F2008C00323:reg:120:p15
Version: federal_register_of_legislation:F2008C00323
Segment Type: reg
Provision Reference: reg 120 (pt 15/23)
Character Range: 277115–280423

configuration and the various parameters which are measured to establish the flow-rate of the CVS pump. All the parameters related to the pump are simultaneously measured with the parameters related to the flowmeter which is connected in series with the pump. The calculated flow-rate (given in m3/min. at pump inlet, absolute pressure and temperature) can then be plotted versus a correlation function which is the value of a specific combination of pump parameters. The linear equation which relates the pump flow and the correlation function is then determined. In the event that a CVS has a multiple speed drive, a calibration for each range used shall be performed.

         4.2.2. This calibration procedure is based on the measurement of the absolute values of the pump and flowmeter parameters that relate the flow rate at each point. Three conditions shall be maintained to ensure the accuracy and integrity of the calibration curve:

         4.2.2.1. the pump pressures shall be measured at tappings on the pump rather than at the external piping on the pump inlet and outlet. Pressure taps that are mounted at the top centre and bottom centre of the pump drive headplate are exposed to the actual pump cavity pressures, and therefore reflect the absolute pressure differentials;

         4.2.2.2. temperature stability shall be maintained during the calibration. The laminar flow-meter is sensitive to inlet temperature oscillations which cause the data points to be scattered. Gradual changes of  1 K in temperature are acceptable as long as they occur over a period of several minutes;

         4.2.2.3. all connections between the flowmeter and the CVS pump shall be free of any leakage.

         4.2.3. During an exhaust emission test, the measurement of these same pump parameters enables the user to calculate the flow rate from the calibration equation.

         4.2.3.1. Figure 6/2 of this Appendix shows one possible test set-up. Variations are permissible, provided that they are approved by the administration granting the approval as being of comparable accuracy. If the set-up shown in Appendix 5, Figure 5/3, is used, the following data shall be found within the limits of precision given:

                                               barometric pressure (corrected)(Pb)    0.03 kPa

                                             ambient temperature (T)    0.2 K

                                             air temperature at LFE (ETI)    0.15 K

                                             pressure depression upstream of LFE (EPI)   0.01 kPa

                                             pressure drop across the LFE matrix (EDP)   0.0015 kPa

                                             air temperature at CVS pump inlet (PTI)   0.2 K

                                             air temperature at CVS pump outlet (PTO)   0.2 K

                                             pressure depression at CVS pump inlet (PPI)   0.22 kPa

                                             pressure head at CVS pump outlet (PPO)   0.22 kPa

                                             pump revolutions during test period (n)   1 1/min

                                             elapsed time for period (minimum 250 s) (t)   0.1 s

         4.2.3.2. After the system