Document ID: chunk:federal_register_of_legislation:F2023L00129:reg:13:p43
Version: federal_register_of_legislation:F2023L00129
Segment Type: reg
Provision Reference: reg 13 (pt 43/56)
Character Range: 413344–416071

cent. The sample filter manufacturer's measurements reflected in their product ratings may be used to show this requirement. The filter material shall be either:

              (a) Fluorocarbon (PTFE) coated glass fibre, or

              (b) Fluorocarbon (PTFE) membrane.
9.4.4.2. Filter size
 The filter shall be circular with a nominal diameter of 47 mm (tolerance of 46.50  0.6 mm) and an exposed diameter (filter stain diameter) of at least 38 mm.
9.4.4.3. Filter face velocity
 The face velocity through the filter shall be between 0.90 and 1.00 m/s with less than 5 per cent of the recorded flow values exceeding this range. If the total PM mass on the filter exceeds 400 µg, the filter face velocity may be reduced to 0.50 m/s. The face velocity shall be calculated as the volumetric flow rate of the sample at the pressure upstream of the filter and temperature of the filter face, divided by the filter's exposed area.
9.4.5. Weighing chamber and analytical balance specifications
 The chamber (or room) environment shall be free of any ambient contaminants (such as dust, aerosol, or semi-volatile material) that could contaminate the particulate filters. The weighing room shall meet the required specifications for at least 60 min before weighing filters.
9.4.5.1. Weighing chamber conditions
 The temperature of the chamber (or room) in which the particulate filters are conditioned and weighed shall be maintained to within 295 K ± 1 K
(22 °C ± 1 °C) during all filter conditioning and weighing. The humidity shall be maintained to a dew point of 282.5 K ± 1 K (9.5 °C ± 1 °C).
 If the stabilization and weighing environments are separate, the temperature of the stabilization environment shall be maintained at a tolerance of
295 K ± 3 K (22 °C ± 3 °C), but the dew point requirement remains at 282.5 K ± 1 K  (9.5 °C ± 1 °C).
 Humidity and ambient temperature shall be recorded.
9.4.5.2. Reference filter weighing
 At least two unused reference filters shall be weighed within 12 hours of, but preferably at the same time as the sample filter weighing. They shall be the same material as the sample filters. Buoyancy correction shall be applied to the weighings.
 If the weight of any of the reference filters changes between sample filter weighings by more than 10 µg, all sample filters shall be discarded and the emissions test repeated.
 The reference filters shall be periodically replaced based on good engineering judgement, but at least once per year.
9.4.5.3. Analytical balance
 The analytical balance used to determine the filter weight shall meet the linearity verification criterion of paragraph 9.2., Table 7. This implies a precision (standard deviation) of at least 2 µg and a resolution of at