Document ID: chunk:federal_register_of_legislation:F2008C00323:reg:120:p16
Version: federal_register_of_legislation:F2008C00323
Segment Type: reg
Provision Reference: reg 120 (pt 16/23)
Character Range: 280066–283197

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 has been connected as shown in Figure 6/2 of this Appendix, set the variable restrictor in the wide-open position and run the CVS pump for 20 minutes before starting the calibration.

         4.2.3.3. 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 stabilise for three minutes and repeat the data acquisition.

Figure 6/2

PDP-CVS calibration configuration

         4.2.4. Data analysis

         4.2.4.1.  The air flow rate (Qs) at each test point is calculated in standard m3/min. from the flowmeter data using the manufacturer's prescribed method.

         4.2.4.2. The air flow-rate is then converted to pump flow (V0) in m3/rev at absolute pump inlet temperature and pressure.

         where:

                   V0 = pump flow rate at Tp and Pp given in m3/rev.,

                   Qs = air flow at 101.33 kPa and 273.2 K given in m3 in m3/min.,

                   Tp = pump inlet temperature (K),

                   Pp = absolute pump inlet pressure (kPa),

                   n = pump speed in min-1.

         To compensate for the interaction of pump speed pressure variations at the pump and the pump slip rate, the correlation function (x0)  between the pump speed (n), the pressure differential from pump inlet to pump outlet and the absolute pump outlet pressure is then calculated as follows:
where:

                   x0 = correlation function,

                   ΔPp = pressure differential from pump inlet to pump outlet (kPa),

                   Pe = absolute outlet pressure (PPO + Pb)(kPa).

         A linear least-square fit is performed to generate the calibration equations which have the formulae:

         V0 = D0 – M (x0)

         n = A – B (ΔPp)

         D0,  M, A and B are the slope-intercept constants describing the lines.

Figure 6/3

CFV-CVS calibration configuration

         4.2.4.3. A CVS system that has multiple speeds shall be calibrated on each speed used. The calibration curves generated for the ranges shall be approximately parallel and the intercept values (D0) shall increase as the pump flow range decreases.

         If the calibration has been performed carefully, the calculated values from the equation will be within 0.5 per cent of the measured value of V0.  Values of M will vary from one pump to another. Calibration is performed at pump start-up and after major maintenance.

         4.3. Calibration of the critical-flow venturi (CFV)

         4.3.1. Calibration of the CFV is based upon the flow equation for a critical venturi:

where:

         Qs = flow,

         Kv = calibration coefficient,

         P = absolute pressure (kPa),