ANNEX III TEST PROCEDURE

Appendix 5 CALIBRATION PROCEDURE

2. CALIBRATION OF THE CVS-SYSTEM

2.2. Calibration of the Positive Displacement Pump (PDP)

2.2.1. Data analysis

The air flowrate (Q_s) 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,

Q_s

=

air flow rate at standard conditions (101,3 kPa, 273 K), m³/s

T

=

temperature at pump inlet, K

p_A

=

absolute pressure at pump inlet (p_B-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,

Δp_p

=

pressure differential from pump inlet to pump outlet, kPa

p_A

=

absolute outlet pressure at pump outlet, kPa

A linear least-square fit shall be performed to generate the calibration equation as follows:

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 maintenance, and if the total system verification (Section 2.4) indicates a change of the slip rate.