Document ID: chunk:federal_register_of_legislation:F2024L00446:reg:9:p22
Version: federal_register_of_legislation:F2024L00446
Segment Type: reg
Provision Reference: reg 9 (pt 22/37)
Character Range: 1839972–1843009

enclosure
               The fixed-volume enclosure shall be constructed with rigid panels that maintain a fixed enclosure volume, and meet the requirements below.
              4.2.2.1. The enclosure shall be equipped with an outlet flow stream that withdraws air at a low, constant rate from the enclosure throughout the test. An inlet flow stream may provide make-up air to balance the outgoing flow with incoming ambient air. Inlet air shall be filtered with activated carbon to provide a relatively constant hydrocarbon level. Any method of volume accommodation shall maintain the differential between the enclosure internal pressure and the barometric pressure between 0 and -0.5 kPa.
              4.2.2.2. The equipment shall be capable of measuring the mass of hydrocarbon in the inlet and outlet flow streams with a resolution of 0.01 gram. A bag sampling system may be used to collect a proportional sample of the air withdrawn from and admitted to the enclosure. Alternatively, the inlet and outlet flow streams may be continuously analysed using an on-line FID analyser and integrated with the flow measurements to provide a continuous record of the mass hydrocarbon removal.
              4.2.3. Calibration of the enclosure
              4.2.3.1. Initial determination of internal volume of the enclosure
              4.2.3.1.1. Before its initial use, the internal volume of the chamber shall be determined as follows:
              The internal dimensions of the chamber are carefully measured, allowing for any irregularities such as bracing struts. The internal volume of the chamber is determined from these measurements.
              For variable-volume enclosures, the enclosure shall be latched to a fixed volume when the enclosure is held at an ambient temperature of 30 °C or at the choice of the manufacturer 29 °C. This nominal volume shall be repeatable within 0.5 per cent of the reported value.
              4.2.3.1.2. The net internal volume is determined by subtracting 1.42 m3 from the internal volume of the chamber. Alternatively the volume of the test vehicle with the luggage compartment and windows open may be used instead of the 1.42 m3.
              4.2.3.1.3. The chamber shall be checked as in paragraph 4.2.3.3. of this annex. If the propane mass does not correspond to the injected mass to within 2 per cent, then corrective action is required.
              4.2.3.2. Determination of chamber background emissions
              This operation determines that the chamber does not contain any materials that emit significant amounts of hydrocarbons. The check shall be carried out at the enclosure's introduction to service, after any operations in the enclosure which may affect background emissions and at a frequency of at least once per year.
              4.2.3.2.1. Variable-volume enclosures may be operated in either latched or unlatched volume configuration, as described in paragraph 4.2.3.1.1. of this annex, ambient temperatures shall be maintained at 35 °C  2 °C, or at the