Document ID: chunk:federal_register_of_legislation:F2012C00283:reg:21:p10
Version: federal_register_of_legislation:F2012C00283
Segment Type: reg
Provision Reference: reg 21 (pt 10/39)
Character Range: 284027–286947

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

              2.2.2.1. 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;

              2.2.2.2. 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;

              2.2.2.3. All connections between the flow-meter and the CVS pump shall be free of any leakage.

              2.2.3.  During an exhaust emission test, the measurement of these same pump parameters enables the user to calculate the flow rate from the calibration equation.
              2.2.4.  Figure 8 of this appendix shows one possible test set-up. Variations are permissible, provided that the Technical Service approves them as being of comparable accuracy. If the set-up shown in Figure 8 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 min-1
  Elapsed time for period (minimum 250 s) (t) 0.1 s

Figure 8
PDP Calibration Configuration

              2.2.5. After the system has been connected as shown in Figure 8 of this appendix, set the variable restrictor in the wide-open position and run the CVS pump for 20 minutes before starting the calibration.
              2.2.6. Reset the restrictor valve to a more restricted condition in an increment of pump inlet depression (about 1 kPa) that will yield a minimum of six data points for the total calibration. Allow the system to stabilize for three minutes and repeat the data acquisition.
              2.2.7. The air flow rate (Qs) at each test point is calculated in standard m3/min from the flow-meter data using the manufacturer's prescribed method.
              2.2.8. The air flow-rate is then converted to pump flow (V0) in m3/rev at absolute pump