Test procedure.
Test procedure.
(1) Couple the diesel engine to the dynamometer and connect the sampling and measurement devices specified in § 7.86.
(2) A minimum time of 10 minutes is required for each measuring point.
(3) Prior to testing, condition and weigh the particulate filters as follows:
(i) At least 1 hour before the test, each filter (pair) shall be placed in a closed, but unsealed, petri dish and placed in a weighing chamber (room) for stabilization.
(ii) At the end of the stabilization period, each filter (pair) shall be weighed. The reading is the tare weight.
(iii) The filter (pair) shall then be stored in a closed petri dish or a filter holder, both of which shall remain in the weighing chamber (room) until needed for testing.
(iv) The filter (pair) must be re-weighed if not used within 8 hours of its removal from the weighing chamber (room).
(4) Run the engine.
(i) The parameter for fa shall be calculated in accordance with § 7.87(a)(3).
(ii) The air inlet and exhaust backpressure restrictions on the engine shall be set as specified in §§ 7.87(a)(3) (iii) and (iv).
(iii) The dilution air shall be set to obtain a maximum filter face temperature of 125 °F (52 °C) or less at each test mode.
(iv) The total dilution ratio shall not be less than 4.
(5) The engine shall be at a steady state condition before starting the test modes.
(i) The engine speed and torque shall be measured and recorded at each test mode.
(ii) The data required for use in the particulate index calculation specified in paragraph (a)(9) of this section shall be measured and recorded at each test mode.
(6) A 1.0 ±0.1 percent CH4, by volume shall be injected into the engine's intake air for category A engines.
(7) Operate the engine at each rated speed and horsepower rating requested by the applicant according to Table E–3 to collect particulate on the primary filter.
(i) One pair of single filters shall be collected or eight multiple filter pairs shall be collected.
(ii) Particulate sampling shall be started after the engine has reached a steady-state condition.
(iii) The sampling time required per mode shall be either a minimum of 20 seconds for the single filter method or a minimum of 60 seconds for the multiple filter method.
(iv) The minimum particulate loading specified in §§ 7.86(c)(18) (iii) or (iv) shall be done.