Document ID: chunk:federal_register_of_legislation:F2023C00229:reg:110:p6
Version: federal_register_of_legislation:F2023C00229
Segment Type: reg
Provision Reference: reg 110 (pt 6/59)
Character Range: 618580–621509

rp = ratio of the SSV throat to inlet absolute, static pressure =

              rD = ratio of the SSV throat diameter, d, to the inlet pipe inner diameter =

              To determine the range of subsonic flow, Cd shall be plotted as a function of Reynolds number at the SSV throat. The Re at the SSV throat is calculated with the following formula:
              where:

              A1 = a collection of constants and units conversions

              QSSV = air flow rate at standard conditions (101,3 kPa, 273 K), m3/s
              d = diameter of the SSV throat, m
              μ = absolute or dynamic viscosity of the gas, calculated with the following formula:

              b = empirical constant =

              S = empirical constant = 110,4 K

              Because QSSV is an input to the Re formula, the calculations must be started with an initial guess for QSSV or Cd of the calibration venturi, and repeated until QSSV converges. The convergence method must be accurate to 0,1 % of point or better.

              For a minimum of sixteen points in the region of subsonic flow, the calculated values of Cd from the resulting calibration curve fit equation must be within ± 0,5 % of the measured Cd for each calibration point.'

         (viii) Former section 2.4 becomes Section 2.5.

         (ix)    Section 3 is replaced by the following:

        '3.  CALIBRATION OF THE PARTICULATE MEASURING SYSTEM

        3.1.  Introduction

              The calibration of the particulate measurement is limited to the flow meters used to determine sample flow and dilution ratio. Each flow meter shall be calibrated as often as necessary to fulfil the accuracy requirements of this Directive. The calibration method that shall be used is described in section 3.2.

        3.2.  Flow measurement

        3.2.1. Periodical calibration

                -          To fulfil the absolute accuracy of the flow measurements as specified in section 2.2 of Appendix 4 to this Annex, the flow meter or the flow measurement instrumentation shall be calibrated with an accurate flow meter traceable to international and/or national standards.

                -          If the sample gas flow is determined by differential flow measurement the flow meter or the flow measurement instrumenta- tion shall be calibrated in one of the following procedures, such that the probe flow qmp into the tunnel shall fulfil the accu- racy requirements of section 4.2.5.2 of Appendix 4 to this Annex:

                  (a) The flow meter for qmdw shall be connected in series to the flow meter for qmdew, the difference between the two flow meters shall be calibrated for at least 5 set points with flow values equally spaced between the lowest qmdw value used during the test and the value of qmdew used during the test. The dilution tunnel may be bypassed.

                  (b) A calibrated mass flow device shall be connected in