Document ID: chunk:federal_register_of_legislation:F2024C00356:reg:3:p15
Version: federal_register_of_legislation:F2024C00356
Segment Type: reg
Provision Reference: reg 3 (pt 15/18)
Character Range: 434689–437647

2 °C) [309 K 2 K (36 2 °C) throughout the 4-hour period mentioned below.
              2.2.3. The enclosure may be sealed and the mixing fan operated for a period of up to 12 hours before the 4-hour background sampling period begins.
              2.2.4. The analyser (if required) shall be calibrated, then zeroed and spanned.
              2.2.5. The enclosure shall be purged until a stable hydrocarbon reading is obtained, and the mixing fan turned on if not already on.
              2.2.6. The chamber is then sealed and the background hydrocarbon concentration, temperature and barometric pressure are measured. These are the initial readings CHCi, Pi, Ti used in the enclosure background calculation.
              2.2.7. The enclosure is allowed to stand undisturbed with the mixing fan on for a period of four hours.
              2.2.8. At the end of this time the same analyser is used to measure the hydrocarbon concentration in the chamber. The temperature and the barometric pressure are also measured. These are the final readings CHCf, Pf, Tf.
              2.2.9. The change in mass of hydrocarbons in the enclosure shall be calculated over the time of the test in accordance with paragraph 2.4. below and shall not exceed 0.05 g.
              2.3. Calibration and hydrocarbon retention test of the chamber
               The calibration and hydrocarbon retention test in the chamber provides a check on the calculated volume in paragraph 2.1. above and also measures any leak rate. The enclosure leak rate shall be determined at the enclosure's introduction to service, after any operations in the enclosure which may affect the integrity of the enclosure, and at least monthly thereafter. If six consecutive monthly retention checks are successfully completed without corrective action, the enclosure leak rate may be determined quarterly thereafter as long as no corrective action is required.
              2.3.1. The enclosure shall be purged until a stable hydrocarbon concentration is reached. The mixing fan is turned on, if not already switched on. The hydrocarbon analyser is zeroed, calibrated if required, and spanned.
              2.3.2. 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.
              2.3.3. The ambient temperature control system is then turned on (if not already on) and adjusted for an initial temperature of 308 K (35 °C) [309 K (36 °C)].
              2.3.4. When the enclosure stabilises at 308 K 2 K (35 2 °C) [309 K 2 K (36 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.
              2.3.5. A quantity of approximately 4 grams of propane is injected into the enclosure. The mass of propane shall be measured to an accuracy and