Document ID: chunk:federal_register_of_legislation:F2012C00283:reg:3:p12
Version: federal_register_of_legislation:F2012C00283
Segment Type: reg
Provision Reference: reg 3 (pt 12/18)
Character Range: 396035–398995

and luggage compartment(s) opened shall be moved into the measuring chamber. The mixing fan(s) shall be adjusted in such a way as to maintain a minimum air circulation speed of 8 km/h under the fuel tank of the test vehicle.

              5.7.4. The hydrocarbon analyser shall be zeroed and spanned immediately before the test.

              5.7.5. The enclosure doors shall be closed and gas-tight sealed.

              5.7.6. Within 10 minutes of closing and sealing the doors, the hydrocarbon concentration, temperature and barometric pressure are measured to give the initial readings CHCi, Pi and Ti for the diurnal test. This is the point where time Tstart = 0.

              5.7.7. The hydrocarbon analyser shall be zeroed and spanned immediately before the end of the test.

              5.7.8. The end of the emission sampling period occurs 24 hours 6 minutes after the beginning of the initial sampling, as specified in paragraph 5.7.6. above. The time elapsed is recorded. The hydrocarbon concentration, temperature and barometric pressure are measured to give the final readings CHCf, Pf and Tf for the diurnal test used for the calculation in paragraph 6. This completes the evaporative emission test procedure.

              6. Calculation

              6.1. The evaporative emission tests described in paragraph 5. allow the hydrocarbon emissions from the diurnal and hot soak phases to be calculated. Evaporative losses from each of theses phases is calculated using the initial and final hydrocarbon concentrations, temperatures and pressures in the enclosure, together with the net enclosure volume. The formula below is used:

 Where:
 MHC      =  hydrocarbon mass in grams,
 MHC,out  =  mass of hydrocarbon exiting the enclosure, in the case of fixed-volume enclosures for diurnal emission testing (grams),
 MHC,i    =  mass of hydrocarbon entering the enclosure, in the case of fixed-volume enclosures for diurnal emission testing (grams),
 CHC      =  measured hydrocarbon concentration in the enclosure (ppm volume in C1 equivalent),
 V        =  net enclosure volume in cubic metres corrected for the volume of the vehicle, with the windows and the luggage compartment open. If the volume of the vehicle is not determined a volume of 1.42 m3 is subtracted,
 T        =  ambient chamber temperature, in K,
 P        =  barometric pressure in kPa,
 H/C      =  hydrogen to carbon ratio,
 k        =  1.2  (12 + H/C);

 Where:
 i       =  is the initial reading,
 f       =  is the final reading,
 H/C     =  is taken to be 2.33 for diurnal test losses,
 H/C     =  is taken to be 2.20 for hot soak losses.

              6.2. Overall results of test

               The overall hydrocarbon mass emission for the vehicle is taken to be:
Mtotal = MDI + MHS
 Where:
 Mtotal  =  overall mass emissions of the vehicle (grams),
 MDI     =  hydrocarbon mass emission for diurnal test (grams),
 MHS     =  hydrocarbon mass emission for