Document ID: chunk:federal_register_of_legislation:F2024C00356:reg:21:p19
Version: federal_register_of_legislation:F2024C00356
Segment Type: reg
Provision Reference: reg 21 (pt 19/35)
Character Range: 339941–342976

2.4.9.  The efficiency of the converter shall be tested at least once a week.

3.  Reference gases

3.1.  Pure gases

               The following pure gases shall be available, if necessary, for calibration and operation:

               Purified nitrogen: (purity: ≤ 1 ppm C, ≤ 1 ppm CO, ≤ 400 ppm CO2, ≤ 0.1 ppm NO);

               Purified synthetic air: (purity: ≤ 1 ppm C, ≤ 1 ppm CO, ≤ 400 ppm CO2, ≤ 0.1 ppm NO); oxygen content between 18 and 21 per cent volume;

                Purified oxygen: (purity > 99.5 per cent vol. O2);

               Purified hydrogen (and mixture containing helium): (purity ≤ 1 ppm C, ≤400 ppm CO2);

               Carbon monoxide: (minimum purity 99.5 per cent);

               Propane: (minimum purity 99.5 per cent).

3.2. Calibration and span gases
               Mixtures of gases having the following chemical compositions shall be available:

               (a) C3 H8 and purified synthetic air (see paragraph 3.1. above);

               (b) CO and purified nitrogen;

               (c) CO2 and purified nitrogen.

               NO and purified nitrogen (the amount of NO2 contained in this calibration gas shall not exceed 5 per cent of the NO content).

               The true concentration of a calibration gas shall be within 2 per cent of the stated figure.

Annex 4a -Appendix 4
  Particulate mass emissions measurement equipment
              1. Specification
              1.1. System Overview
              1.1.1. The particulate sampling unit shall consist of a sampling probe located in the dilution tunnel, a particle transfer tube, a filter holder, a partial-flow pump, and flow rate regulators and measuring units.
              1.1.2. It is recommended that a particle size pre-classifier (e.g. cyclone or impactor) be employed upstream of the filter holder. However, a sampling probe, acting as an appropriate size-classification device such as that shown in Figure 13, is acceptable.
              1.2. General Requirements
              1.2.1. The sampling probe for the test gas flow for particulates shall be so arranged within the dilution tract that a representative sample gas flow can be taken from the homogeneous air/exhaust mixture.
              1.2.2. The particulate sample flow rate shall be proportional to the total flow of diluted exhaust gas in the dilution tunnel to within a tolerance of ±5 per cent of the particulate sample flow rate.
              1.2.3. The sampled dilute exhaust gas shall be maintained at a temperature below 325 K (52 °C) within 20 cm upstream or downstream of the particulate filter face, except in the case of a regeneration test where the temperature must be below 192 °C.
              1.2.4. The particulate sample shall be collected on a single filter mounted within a holder in the sampled dilute exhaust gas flow.
              1.2.5. All parts of the dilution system and the sampling system from the exhaust pipe up to the filter holder, which are in contact with raw and diluted exhaust gas, shall be designed