Document ID: chunk:federal_register_of_legislation:F2024L00446:reg:9:p24
Version: federal_register_of_legislation:F2024L00446
Segment Type: reg
Provision Reference: reg 9 (pt 24/37)
Character Range: 1845489–1848449

and spanned.
              4.2.3.3.2. On variable-volume enclosures, the enclosure shall be latched to the nominal volume position. On fixed-volume enclosures the outlet and inlet flow streams shall be closed.
              4.2.3.3.3. The ambient temperature control system is then turned on (if not already on) and adjusted for an initial temperature of 35 °C, or at the choice of the manufacturer 36 °C.
              4.2.3.3.4. When the enclosure stabilises at 35 °C  2 °C, or at the choice of the manufacturer 36 °C  2 °C, the enclosure is sealed and the background concentration, temperature and barometric pressure measured. These are the initial readings CHCi, Pi, Ti used in the enclosure calibration.
              4.2.3.3.5. A quantity of approximately 4 grams of propane is injected into the enclosure. The mass of propane shall be measured to an accuracy and precision of 2 per cent of the measured value.
              4.2.3.3.6. The contents of the chamber shall be allowed to mix for five minutes and then the hydrocarbon concentration, temperature and barometric pressure are measured. These are the readings CHCf, Pf, Tf for the calibration of the enclosure as well as the initial readings CHCi, Pi, Ti for the retention check.
              4.2.3.3.7. Based on the readings taken according to paragraph 4.2.3.3.4. and 4.2.3.3.6. of this annex and the formula in paragraph 4.2.3.4. of this annex, the mass of propane in the enclosure is calculated. This shall be within ±2 per cent of the mass of propane measured in paragraph 4.2.3.3.5. of this annex.
              4.2.3.3.8. For variable-volume enclosures the enclosure shall be unlatched from the nominal volume configuration. For fixed-volume enclosures, the outlet and inlet flow streams shall be opened.
              4.2.3.3.9. The process is then begun of cycling the ambient temperature from 35 °C to 20 °C and back to 35 °C, or at the choice of the manufacturer 35.6 °C to 22.2 °C and back to 35.6 °C, over a 24-hour period according to the profile, or the alternative profile, specified in paragraph 6.5.9. of this annex within 15 minutes of sealing the enclosure. (Tolerances as specified in paragraph 6.5.9.1. of this annex.)
              4.2.3.3.10. At the completion of the 24-hour cycling period, the final hydrocarbon concentration, temperature and barometric pressure are measured and recorded. These are the final readings CHCf, Pf, Tf for the hydrocarbon retention check.
              4.2.3.3.11. Using the formula in paragraph 4.2.3.4. of this annex, the hydrocarbon mass is then calculated from the readings taken in paragraphs 4.2.3.3.6. and 4.2.3.3.10. of this annex. The mass may not differ by more than 3 per cent from the hydrocarbon mass given in paragraph 4.2.3.3.7. of this annex.
              4.2.3.4. Calculations
               The calculation of net hydrocarbon mass change within the enclosure is used to determine the chamber's hydrocarbon background