lexiara

(vi)

Commission Directive 2005/78/EC of 14 November 2005 implementing Directive 2005/55/EC of the European Parliament and of the Council on the approximation of the laws of the Member States relating to the measures to be taken against the emission of gaseous and particulate pollutants from compression-ignition engines for use in vehicles, and the emission of gaseous pollutants from positive ignition engines fuelled with natural gas or liquefied petroleum gas for use in vehicles and amending Annexes I, II, III, IV and VI thereto (Text with EEA relevance) · European Union

The following section 2.4 is inserted: ‘2.4. Calibration of the Subsonic Venturi (SSV) Calibration of the SSV is based upon the flow equation for a subsonic venturi. Gas flow is a function of inlet pressure and temperature, pressure drop between the SSV inlet and throat. 2.4.1. Data analysis The air flowrate (QSSV) at each restriction setting (minimum 16 settings) shall be calculated in standard m3/min from the flowmeter data using the manufacturer's prescribed method. The discharge coefficient shall be calculated from the calibration data for each setting as follows: Text of image QSSV = A0d2Cdpp √ [1 T (rp1,4286 - rp1,7143) × (1 1 - rD 4rp1,4286)] where: To determine the range of subsonic flow, C d 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: Text of image Re = A1 QSSV dμ where: Because Q SSV is an input to the Re formula, the calculations must be started with an initial guess for Q SSV or C d of the calibration venturi, and repeated until Q SSV 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 C d from the resulting calibration curve fit equation must be within ± 0,5 % of the measured C d for each calibration point.’ Q SSV | = | air flow rate at standard conditions (101,3 kPa, 273 K), m3/s T | = | temperature at the venturi inlet, K d | = | diameter of the SSV throat, m r p | = | ratio of the SSV throat to inlet absolute, static pressure = Text of image 1 - ΔP PA r D | = | ratio of the SSV throat diameter, d, to the inlet pipe inner diameter = Text of image d D A 1 | = | a collection of constants and units conversions Text of image = 25,55152 (1m3) (min s) (mm m) Q SSV | = | 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: Text of image μ = bT 3/2 S + T = bT 1/2 1 + S T kg/m–s b | = | empirical constant = Text of image 1,458 × 10 6 kg msK 1/2 S | = | empirical constant = 110,4 K

· All articles ·

Source: EUR-Lex (Cellar) · retrieved 2026-11-10 · Text as adopted (Official Journal); later amendments are not incorporated in this text.