Document ID: chunk:federal_register_of_legislation:F2023C00229:reg:9:p34
Version: federal_register_of_legislation:F2023C00229
Segment Type: reg
Provision Reference: reg 9 (pt 34/71)
Character Range: 304313–307449

influence calibration.

2.                                 CALIBRATION OF THE CVS-SYSTEM

2.1.                            General

              The CVS system shall be calibrated by using an accurate flowmeter traceable to national or international standards and a restricting device. The flow through the system shall be measured at different restriction settings, and the control parameters of the system shall be measured and related to the flow.

              Various types of flowmeters may be used, e.g. calibrated venturi, calibrated laminar flowmeter, calibrated turbinemeter.

2.2.                            Calibration of the Positive Displacement Pump (PDP)

              All parameters related to the pump shall be simultaneously measured with the parameters related to the flowmeter which is connected in series with the pump. The calculated flow rate (in m3/min at pump inlet, absolute pressure and temperature) shall 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 shall then be determined. If a CVS has a multiple speed drive, the calibration shall be performed for each range used. Temperature stability shall be maintained during calibration.

2.2.1.                        Data analysis

              The air flowrate (Qs) at each restriction setting (minimum six settings) shall be calculated in standard m3/min from the flowmeter data using the manufacturer's prescribed method. The air flow rate shall then be converted to pump flow (V0) in m3/rev at absolute pump inlet temperature and pressure as follows:

              where,

              Qs   = air flow rate at standard conditions (101,3 kPa, 273 K), m3/s T = temperature at pump inlet, K
              pA   = absolute pressure at pump inlet (pB-p1), kPa n = pump speed, rev/s

              To account for the interaction of pressure variations at the pump and the pump slip rate, the correlation function (X0) between pump speed, pressure differential from pump inlet to pump outlet and absolute pump outlet pressure shall be calculated as follows:

              where,

              Δpp = pressure differential from pump inlet to pump outlet, kPa  pA   = absolute outlet pressure at pump outlet, kPa
              A linear least-square fit shall be performed to generate the calibration equation as follows:

        V0 = D0 - m × (X0)

              D0 and m are the intercept and slope constants, respectively, describing the regression lines.

              For a CVS system with multiple speeds, the calibration curves generated for the different pump flow ranges shall be approximately parallel, and the intercept values (D0) shall increase as the pump flow range decreases.

              The calculated values from the equation shall be within ± 0,5 % of the measured value of V0. Values of m will vary from one pump to another. Particulate influx over time will cause the pump slip to decrease, as reflected by lower values for m. Therefore, calibration shall be performed at pump start-up, after major