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Division 3.9.1 Reference meter conversions

United Kingdom

Original text. Later amendments are not shown.

The calibration equations in this section use molar flow rate, ṅ ref , as a reference quantity. If the adopted reference meter outputs a flow rate in a different quantity, such as standard volume rate, V̇ stdref actual volume rate, V̇ actdref, or mass rate, ṁ ref, the reference meter output shall be converted to a molar flow rate by means of equations (7-136), (7-137) and (7-138), noting that while values for volume rate, mass rate, pressure, temperature, and molar mass may change during an emission test, they should be kept as constant as practical for each individual set point during a flow meter calibration:

ṅ ref = V stdref × p std T std × R = V actref × p act T act × R = ṁ ref M mix (7-136)

where:

ṅ ref

  • reference molar flow rate [mol/s]

    • V̇ stdref

  • reference volume flow rate, corrected to a standard pressure and a standard temperature [m3/s]

    • V̇ actref

  • reference volume flow rate, at the actual pressure and temperature [m3/s]

    • ṁ ref

  • reference mass flow [g/s]

    • p std

  • standard pressure [Pa]

    • p act

  • actual pressure of the gas [Pa]

    • T std

  • standard temperature [K]

    • T act

  • actual temperature of the gas [K]

    • R

  • molar gas constant [J/(mol · K)]

    • M mix

  • molar mass of the gas [g/mol]