Sections 1065.1123 through 1065.1127 appear at 88 FR 4693, Jan. 24, 2023, unless otherwise noted.
The provisions of § 1065.1125 describe system specifications for measuring percent opacity of exhaust for all types of engines. The provisions of § 1065.1127 describe how to use such a system to determine percent opacity of engine exhaust for applications other than locomotives. See 40 CFR 1033.525 for measurement procedures for locomotives.
Smokemeters measure exhaust opacity using full-flow open-path light extinction with a built-in light beam across the exhaust stack or plume. Prepare and install a smokemeter system as follows:
(a) Except as specified in paragraph (d) of this section, use a smokemeter capable of providing continuous measurement that meets the following specifications:
(1) Use an incandescent lamp with a color temperature between (2800 and 3250) K or a different light source with a spectral peak between (550 and 570) nm.
(2) Collimate the light beam to a nominal diameter of 3 centimeters and maximum divergence angle of 6 degrees.
(3) Include a photocell or photodiode as a detector. The detector must have a maximum spectral response between (550 and 570) nm, with less than 4 percent of that maximum response below 430 nm and above 680 nm. These specifications correspond to visual perception with the human eye.
(4) Use a collimating tube with an aperture that matches the diameter of the light beam. Restrict the detector to viewing within a 16 degree included angle.
(5) Optionally use an air curtain across the light source and detector window to minimize deposition of smoke particles, as long as it does not measurably affect the opacity of the sample.
(6) The diagram in the following figure illustrates the smokemeter configuration:
Figure 1 to paragraph (a)(6) of § 1065.1125—Smokemeter Diagram
(b) Smokemeters for locomotive applications must have a full-scale response time of 0.5 seconds or less. Smokemeters for locomotive applications may attenuate signal responses with frequencies higher than 10 Hz with a separate low-pass electronic filter that has the following performance characteristics:
(1) Three decibel point: 10 Hz.
(2) Insertion loss: (0.0 ±0.5) dB.
(3) Selectivity: 12 dB down at 40 Hz minimum.
(4) Attenuation: 27 dB down at 40 Hz minimum.
(c) Configure exhaust systems as follows for measuring exhaust opacity:
(1) For locomotive applications:
(i) Optionally add a stack extension to the locomotive muffler.
(ii) For in-line measurements, the smokemeter is integral to the stack extension.
(iii) For end-of-line measurements, mount the smokemeter directly at the end of the stack extension or muffler.
(iv) For all testing, minimize distance from the optical centerline to the muffler outlet; in no case may it be more than 300 cm. The maximum allowable distance of unducted space upstream of the optical centerline is 50 cm, whether the unducted portion is upstream or downstream of the stack extensions.
(2) Meet the following specifications for all other applications:
(i) For in-line measurements, install the smokemeter in an exhaust pipe segment downstream of all engine components. This will typically be part of a laboratory configuration to route the exhaust to an analyzer. The exhaust pipe diameter must be constant within 3 exhaust pipe diameters before and after the smokemeter's optical centerline. The exhaust pipe diameter may not change by more than a 12-degree half-angle within 6 exhaust pipe diameters upstream of the smokemeter's optical centerline.
(ii) For end-of-line measurements with systems that vent exhaust to the ambient, add a stack extension and position the smokemeter such that its optical centerline is (2.5 ±0.625) cm upstream of the stack extension's exit. Configure the exhaust stack and extension such that at least the last 60 cm is a straight pipe with a circular cross section with an approximate inside diameter as specified in the following table:
| Maximum rated power | Approximate exhaust pipe diameter
(mm) |
|---|---|
| kW<40 | 38 |
| 40≤kW<75 | 50 |
| 75≤kW<150 | 76 |
| 150≤kW<225 | 102 |
| 225≤kW<375 | 127 |
| kW≥ 375 | 152 |
(iii) For both in-line and end-of-line measurements, install the smokemeter so its optical centerline is (3 to 10) meters further downstream than the point in the exhaust stream that is farthest downstream considering all the following components: exhaust manifolds, turbocharger outlets, exhaust aftertreatment devices, and junction points for combining exhaust flow from multiple exhaust manifolds.
(3) Orient the light beam perpendicular to the direction of exhaust flow. Install the smokemeter so it does not influence exhaust flow distribution or the shape of the exhaust plume. Set up the smokemeter's optical path length as follows:
(i) For locomotive applications, the optical path length must be at least as wide as the exhaust plume.
(ii) For all other applications, the optical path length must be the same as the diameter of the exhaust flow. For noncircular exhaust configurations, set up the smokemeter such that the light beam's path length is across the longest axis with an optical path length equal to the hydraulic diameter of the exhaust flow.
(4) The smokemeter must not interfere with the engine's ability to meet the exhaust backpressure requirements in § 1065.130(h).
(5) For engines with multiple exhaust outlets, measure opacity using one of the following methods:
(i) Join the exhaust outlets together to form a single flow path and install the smokemeter (3 to 10) m downstream of the point where the exhaust streams converge or the last exhaust aftertreatment device, whichever is farthest downstream.
(ii) Install a smokemeter in each of the exhaust flow paths. Report all measured values. All measured values must comply with standards.
(6) The smokemeter may use purge air or a different method to prevent carbon or other exhaust deposits on the light source and detector. Such a method used with end-of-line measurements may not cause the smoke plume to change by more than 0.5 cm at the smokemeter. If such a method affects the smokemeter's optical path length, follow the smokemeter manufacturer's instructions to properly account for that effect.
(d) You may use smokemeters meeting alternative specifications as follows:
(1) You may use smokemeters that use other electronic or optical techniques if they employ substantially identical measurement principles and produce substantially equivalent results.
(2) You may ask us to approve the use of a smokemeter that relies on partial flow sampling. Follow the instrument manufacturer's installation, calibration, operation, and maintenance procedures if we approve your request. These procedures must include correcting for any change in the path length of the exhaust plume relative to the diameter of the engine's exhaust outlet.
The test procedure described in this section applies for everything other than locomotives. The test consists of a sequence of engine operating points on an engine dynamometer to measure exhaust opacity during specific engine operating modes to represent in-use operation. Measure opacity using the following procedure:
(a) Use the equipment and procedures specified in this part 1065.
(b) Calibrate the smokemeter as follows:
(1) Calibrate using neutral density filters with approximately 10, 20, and 40 percent opacity. Confirm that the opacity values for each of these reference filters are NIST-traceable within 185 days of testing, or within 370 days of testing if you consistently protect the reference filters from light exposure between tests.
(2) Before each test and optionally during engine idle modes, remove the smokemeter from the exhaust stream, if applicable, and calibrate as follows:
(i) Zero. Adjust the smokemeter to give a zero response when there is no detectable smoke.
(ii) Linearity. Insert each of the qualified reference filters in the light path perpendicular to the axis of the light beam and adjust the smokemeter to give a result within 1 percentage point of the named value for each reference filter.
(c) Prepare the engine, dynamometer, and smokemeter for testing as follows:
(1) Set up the engine to run in a configuration that represents in-use operation.
(2) Determine the smokemeter's optical path length to the nearest mm.
(3) If the smokemeter uses purge air or another method to prevent deposits on the light source and detector, adjust the system according to the system manufacturer's instructions and activate the system before starting the engine.
(4) Program the dynamometer to operate in torque-control mode throughout testing. Determine the dynamometer load needed to meet the cycle requirements in paragraphs (d)(4)(ii) and (iv) of this section.
(5) You may program the dynamometer to apply motoring assist with negative flywheel torque, but only during the first 0.5 seconds of the acceleration events in paragraphs (d)(4)(i) and (ii) of this section. Negative flywheel torque may not exceed 13.6 N·m.
(d) Operate the engine and dynamometer over repeated test runs of the duty cycle illustrated in Figure 1 of this appendix. As noted in the figure, the test run includes an acceleration mode from points A through F in the figure, followed by a lugging mode from points I to J. Detailed specifications for testing apply as follows:
(1) Continuously record opacity, engine speed, engine torque, and operator demand over the course of the entire test at 10 Hz; however, you may interrupt measurements to recalibrate during each idle mode.
(2) Precondition the engine by operating it for 10 minutes at maximum mapped power.
(3) Operate the engine for (5.0 to 5.5) minutes at warm idle speed, ƒnidle, with load set to Curb Idle Transmission Torque.
(4) Operate the engine and dynamometer as follows during the acceleration mode:
(i) First acceleration event—AB. Partially increase and hold operator demand to stabilize engine speed briefly at (200 ±50) r/min above ƒnidle. The start of this acceleration is the start of the test (t = 0 s).
(ii) Second acceleration event—CD. As soon as measured engine speed is within the range specified in paragraph (d)(4)(i) of this section, but not more than 3 seconds after the start of the test, rapidly set and hold operator demand at maximum. Operate the dynamometer using a preselected load to accelerate engine speed to 85 percent of maximum test speed, ƒntest, in (5 ±1.5) seconds. The engine speed throughout the acceleration must be within ±100 r/min of a target represented by a linear transition between the low and high engine speed targets.
(iii) Transition—DEF. As soon as measured engine speed reaches 85 percent of ƒntest, rapidly set and hold operator demand at minimum and simultaneously apply a load to decelerate to intermediate speed in (0.5 to 3.5) seconds. Use the same load identified for the acceleration event in paragraph (d)(4)(iv) of this section.
(iv) Third acceleration event—FGH. Rapidly set and hold operator demand at maximum when the engine is within ±50 r/min of intermediate speed. Operate the dynamometer using a preselected load to accelerate engine speed to at least 95 percent of ƒntest in (10 ±2) seconds.
(5) Operate the engine and dynamometer as follows during the lugging mode:
(i) Transition—HI. When the engine reaches 95 percent of ƒntest, keep operator demand at maximum and immediately set dynamometer load to control the engine at maximum mapped power. Continue the transition segment for (50 to 60) seconds. For at least the last 10 seconds of the transition segment, hold engine speed within ±50 r/min of ƒntest and power at or above 95 percent of maximum mapped power. Conclude the transition by increasing dynamometer load to reduce engine speed as specified in paragraph (d)(4)(iii) of this section, keeping operator demand at maximum.
(ii) Lugging—IJ. Apply dynamometer loading as needed to decrease engine speed from 50 r/min below fntest to intermediate speed in (35 ±5) seconds. The engine speed must remain within ±100 r/min of a target represented by a linear transition between the low and high engine speed targets.
(6) Return the dynamometer and engine controls to the idle position described in paragraph (d)(3) of this section within 60 seconds of completing the lugging mode.
(7) Repeat the procedures in paragraphs (d)(3) through (6) of this section as needed to complete three valid test runs. If you fail to meet the specifications during a test run, continue to follow the specified duty cycle before starting the next test run.
(8) Shut down the engine or remove the smokemeter from the exhaust stream to verify zero and linearity. Void the test if the smokemeter reports more than 2 percent opacity for the zero verification, or if the smokemeter's error for any of the linearity checks specified in paragraph (b)(2) of this section is more than 2 percent.
(e) Analyze and validate the test data as follows:
(1) Divide each test run into test segments. Each successive test segment starts when the preceding segment ends. Identify the test segments based on the following criteria:
(i) The idle mode specified in paragraph (d)(3) of this section for the first test run starts immediately after engine preconditioning is complete. The idle mode for later test runs must start within 60 seconds after the end of the previous test run as specified in paragraph (d)(6) of this section. The idle mode ends when operator demand increases for the first acceleration event (Points A and B).
(ii) The first acceleration event in paragraph (d)(4)(i) of this section ends when operator demand is set to maximum for the second acceleration event (Point C).
(iii) The second acceleration event in paragraph (d)(4)(ii) of this section ends when the engine reaches 85 percent of maximum test speed, ƒntest, (Point D) and operator demand is set to minimum (Point E).
(iv) The transition period in paragraph (d)(4)(iii) of this section ends when operator demand is set to maximum (Point F).
(v) The third acceleration event in paragraph (d)(4)(iv) of this section ends when engine speed reaches 95 percent of ƒntest (Point H).
(vi) The transition period in paragraph (d)(5)(i) of this section ends when engine speed first decreases to a point more than 50 r/min below ƒntest (Point I).
(vii) The lugging mode in paragraph (d)(5)(ii) of this section ends when the engine reaches intermediate speed (Point J).
(2) Convert measured instantaneous values to standard opacity values, κstd, based on the appropriate optical path length specified in Table 1 of § 1065.1125 using the following equation:
Where:
κstd = standard instantaneous percent opacity.
κmeas = measured instantaneous percent opacity.
lstd = standard optical path length corresponding with engine power, in millimeters.
lmeas = the smokemeter's optical path length, in millimeters.
Example for an engine < 40 kW:
κmeas = 14.1%
lstd = 38 mm
lmeas = 41 mm
(3) Select opacity results from corrected measurements collected across test segments as follows:
(i) Divide measurements from acceleration and lugging modes into half-second intervals. Determine average opacity values during each half-second interval.
(ii) Identify the 15 highest half-second values during the acceleration mode of each test run.
(iii) Identify the five highest half-second values during the lugging mode of each test run.
(iv) Identify the three overall highest values from paragraphs (e)(3)(ii) and (iii) of this section for each test run.
(f) Determine percent opacity as follows:
(1) Acceleration. Determine the percent opacity for the acceleration mode by calculating the average of the 45 readings from paragraph (e)(3)(ii) of this section.
(2) Lugging. Determine the percent opacity for the lugging mode by calculating the average of the 15 readings from paragraph (e)(3)(iii) of this section.
(3) Peak. Determine the percent opacity for the peaks in either acceleration or lugging mode by calculating the average of the 9 readings from paragraph (e)(3)(iv) of this section.
(g) Submit the following information in addition to what is required by § 1065.695:
(1) Exhaust pipe diameter(s).
(2) Measured maximum exhaust system backpressure over the entire test.
(3) Most recent date for establishing that each of the reference filters from paragraph (b) of this section are NIST-traceable.
(4) Measured smokemeter zero and linearity values after testing.
(5) 10 Hz data from all valid test runs.
(h) The following figure illustrates the dynamometer controls and engine speeds for exhaust opacity testing:
Figure 1 to paragraph (h) of § 1065.1127—Schemati of Smoke Opacity Duty Cycle
