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(2) Either measure these background concentrations the same way you measure diluted exhaust constituents, or measure them in a way that does not affect your ability to demonstrate compliance with the applicable standards. For example, you may use the following simplifications for background sampling:
(i) You may disregard any proportional sampling requirements.
(ii) You may use unheated gaseous sampling systems.
(iii) You may use unheated PM sampling systems only if we approve it in advance.
(iv) You may use continuous sampling if you use batch sampling for diluted emissions.
(v) You may use batch sampling if you use continuous sampling for diluted emissions.
(3) For removing background PM, we recommend that you filter all dilution air, including primary full-flow dilution air, with high-efficiency particulate air (HEPA) filters that have an initial minimum collection efficiency specification of 99.97% (see §1065.1001 for procedures related to HEPA-filtration efficiencies). Ensure that HEPA filters are installed properly so that background PM does not leak past the HEPA filters. If you choose to correct for background PM without using HEPA filtration, demonstrate that the background PM in the dilution air contributes less than 50% to the net PM collected on the sample filter.
(c) Full-flow dilution; constant-volume sampling (CVS). You may dilute the full flow of raw exhaust in a dilution tunnel that maintains a nominally constant volume flow rate, molar flow rate or mass flow rate of diluted exhaust, as follows:
(1) Construction. Use a tunnel with inside surfaces of 300 series stainless steel. Electrically ground the entire dilution tunnel. We recommend a thin-walled and insulated dilution tunnel to minimize temperature differences between the wall and the exhaust gases.
(2) Pressure control. Maintain static pressure at the location where raw exhaust is introduced into the tunnel within 1.2 kPa of atmospheric pressure. You may use a booster blower to control this pressure. If you test an engine using more careful pressure control and you show by engineering analysis or by test data that you require this level of control to demonstrate compliance at the applicable standards, we will maintain the same level of static pressure control when we test that engine.
(3) Mixing. Introduce raw exhaust into the tunnel by directing it downstream along the centerline of the tunnel. You may introduce a fraction of dilution air radially from the tunnel's inner surface to minimize exhaust interaction with the tunnel walls. You may configure the system with turbulence generators such as orifice plates or fins to achieve good mixing. We recommend a minimum Reynolds number, Re#, of 4000 for the diluted exhaust stream, where Re# is based on the inside diameter of the dilution tunnel. Re# is defined in §1065.640.
(4) Flow measurement preconditioning. You may condition the diluted exhaust before measuring its flow rate, as long as this conditioning takes place downstream of any sample probes, as follows:
(i) You may use flow straighteners, pulsation dampeners, or both of these.
(ii) You may use a filter.
(iii) You may use a heat exchanger to control the temperature upstream of any flow meter. Note paragraph (c)(6) of this section regarding aqueous condensation.
(5) Flow measurement. Section 1065.240 describes measurement instruments for diluted exhaust flow.
(6) Aqueous condensation. You may either prevent aqueous condensation throughout the dilution tunnel or you may measure humidity at the flow meter inlet. Calculations in §1065.645 and §1065.650 account for either method of addressing humidity in the diluted exhaust. Note that preventing aqueous condensation involves more than keeping pure water in a vapor phase (see §1065.1001).
(7) Flow compensation. Maintain nominally constant molar, volumetric or mass flow of diluted exhaust. You may maintain nominally constant flow by either maintaining the temperature and pressure at the flow meter or by directly controlling the flow of diluted exhaust. You may also directly control the flow of proportional samplers to maintain proportional sampling. For an individual test, validate proportional sampling as described in §1065.545.
(d) Partial-flow dilution (PFD). Except as specified in this paragraph (d), you may dilute a partial flow of raw or previously diluted exhaust before measuring emissions. §1065.240 describes PFD-related flow measurement instruments. PFD may consist of constant or varying dilution ratios as described in paragraphs (d)(2) and (3) of this section. An example of a constant dilution ratio PFD is a “secondary dilution PM” measurement system. An example of a varying dilution ratio PFD is a “bag mini-diluter” or BMD.
(1) Applicability. (i) You may not use PFD if the standard-setting part prohibits it.
(ii) You may use PFD to extract a proportional raw exhaust sample for any batch or continuous PM emission sampling over any transient duty cycle only if we have explicitly approved it according to §1065.10 as an alternative procedure to the specified procedure for full-flow CVS.
(iii) You may use PFD to extract a proportional raw exhaust sample for any batch or continuous gaseous emission sampling.
(iv) You may use PFD to extract a proportional raw exhaust sample for any batch or continuous PM emission sampling over any steady-state duty cycle or its ramped-modal cycle (RMC) equivalent.
(v) You may use PFD to extract a proportional raw exhaust sample for any batch or continuous field-testing.
(vi) You may use PFD to extract a proportional diluted exhaust sample from a CVS for any batch or continuous emission sampling.
(vii) You may use PFD to extract a constant raw or diluted exhaust sample for any continuous emission sampling.
(2) Constant dilution-ratio PFD. Do one of the following for constant dilution-ratio PFD:
(i) Dilute an already proportional flow. For example, you may do this as a way of performing secondary dilution from a CVS tunnel to achieve temperature control for PM sampling.
(ii) Continuously measure constituent concentrations. For example, you might dilute to precondition a sample of raw exhaust to control its temperature, humidity, or constituent concentrations upstream of continuous analyzers. In this case, you must take into account the dilution ratio before multiplying the continuous concentration by the sampled exhaust flow rate.
(iii) Extract a proportional sample from the constant dilution ratio PFD system. For example, you might use a variable-flow pump to proportionally fill a gaseous storage medium such as a bag from a PFD system. In this case, the proportional sampling must meet the same specifications as varying dilution ratio PFD in paragraph (d)(3) of this section.
(3) Varying dilution-ratio PFD. All the following provisions apply for varying dilution-ratio PFD:
(i) Use a control system with sensors and actuators that can maintain proportional sampling over intervals as short as 200 ms (i.e., 5 Hz control).
(ii) For control input, you may use any sensor output from one or more measurements; for example, intake-air flow, fuel flow, exhaust flow, engine speed, and intake manifold temperature and pressure.
(iii) Account for any emission transit time in the PFD system.
(iv) You may use preprogrammed data if they have been determined for the specific test site, duty cycle, and test engine from which you dilute emissions.
(v) We recommend that you run practice cycles to meet the validation criteria in §1065.545. Note that you must validate every emission test by meeting the validation criteria with the data from that specific test, not from practice cycles or other tests.
(vi) You may not use a PFD system that requires preparatory tuning or calibration with a CVS or with the emission results from a CVS. Rather, you must be able to independently calibrate the PFD.
(e) Dilution and temperature control of PM samples. Dilute PM samples at least once upstream of transfer lines. You may dilute PM samples upstream of a transfer line using full-flow dilution, or partial-flow dilution immediately downstream of a PM probe. Control sample temperature to a (47 ±5) °C tolerance, as measured anywhere within 20 cm upstream or downstream of the PM storage media (such as a filter). Measure this temperature with a bare-wire junction thermocouple with wires that are (0.500 ±0.025) mm diameter, or with another suitable instrument that has equivalent performance. Heat or cool the PM sample primarily by dilution.
§ 1065.145 Gaseous and PM probes, transfer lines, and sampling system components.
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(a) Continuous and batch sampling. Determine the total mass of each constituent with continuous or batch sampling, as described in §1065.15(c)(2). Both types of sampling systems have probes, transfer lines, and other sampling system components that are described in this section.
(b) Gaseous and PM sample probes. A probe is the first fitting in a sampling system. It protrudes into a raw or diluted exhaust stream to extract a sample, such that its inside and outside surfaces are in contact with the exhaust. A sample is transported out of a probe into a transfer line, as described in paragraph (c) of this section. The following provisions apply to probes:
(1) Probe design and construction. Use sample probes with inside surfaces of 300 series stainless steel or, for raw exhaust sampling, use a nonreactive material capable of withstanding raw exhaust temperatures. Locate sample probes where constituents are mixed to their mean sample concentration. Take into account the mixing of any crankcase emissions that may be routed into the raw exhaust. Locate each probe to minimize interference with the flow to other probes. We recommend that all probes remain free from influences of boundary layers, wakes, and eddies—especially near the outlet of a raw-exhaust tailpipe where unintended dilution might occur. Make sure that purging or back-flushing of a probe does not influence another probe during testing. You may use a single probe to extract a sample of more than one constituent as long as the probe meets all the specifications for each constituent.
(2) Gaseous sample probes. Use either single-port or multi-port probes for sampling gaseous emissions. You may orient these probes in any direction relative to the raw or diluted exhaust flow. For some probes, you must control sample temperatures, as follows:
(i) For probes that extract NOX from diluted exhaust, control the probe's wall temperature to prevent aqueous condensation.
(ii) For probes that extract hydrocarbons for NMHC or NMHCE analysis from the diluted exhaust of compression-ignition engines, 2-stroke spark-ignition engines, or 4-stroke spark-ignition engines below 19 kW, maintain a probe wall temperature tolerance of (191 ±11) °C.
(3) PM sample probes. Use PM probes with a single opening at the end. Orient PM probes to face directly upstream. If you shield a PM probe's opening with a PM pre-classifier such as a hat, you may not use the preclassifier we specify in paragraph (d)(4)(i) of this section. We recommend sizing the inside diameter of PM probes to approximate isokinetic sampling at the expected mean flow rate.
(c) Transfer lines. You may use transfer lines to transport an extracted sample from a probe to an analyzer, storage medium, or dilution system. Minimize the length of all transfer lines by locating analyzers, storage media, and dilution systems as close to probes as practical. We recommend that you minimize the number of bends in transfer lines and that you maximize the radius of any unavoidable bend. Avoid using 90° elbows, tees, and cross-fittings in transfer lines. Where such connections and fittings are necessary, take steps, using good engineering judgment, to ensure that you meet the temperature tolerances in this paragraph (c). This may involve measuring temperature at various locations within transfer lines and fittings. You may use a single transfer line to transport a sample of more than one constituent, as long as the transfer line meets all the specifications for each constituent. The following construction and temperature tolerances apply to transfer lines:
(1) Gaseous samples. Use transfer lines with inside surfaces of 300 series stainless steel, PTFE, Viton TM , or any other material that you demonstrate has better properties for emission sampling. For raw exhaust sampling, use a non-reactive material capable of withstanding raw exhaust temperatures. You may use in-line filters if they do not react with exhaust constituents and if the filter and its housing meet the same temperature requirements as the transfer lines, as follows:
(i) For NOX transfer lines upstream of either an NO2-to-NO converter that meets the specifications of §1065.378 or a chiller that meets the specifications of §1065.376, maintain a sample temperature that prevents aqueous condensation.
(ii) For THC transfer lines for testing compression-ignition engines, 2-stroke spark-ignition engines, or 4-stroke spark-ignition engines below 19 kW, maintain a wall temperature tolerance throughout the entire line of (191 ±11) °C. If you sample from raw exhaust, you may connect an unheated, insulated transfer line directly to a probe. Design the length and insulation of the transfer line to cool the highest expected raw exhaust temperature to no lower than 191 °C, as measured at the transfer line's outlet.
(2) PM samples. We recommend heated transfer lines or a heated enclosure to minimize temperature differences between transfer lines and exhaust constituents. Use transfer lines that are inert with respect to PM and are electrically conductive on the inside surfaces. We recommend using PM transfer lines made of 300 series stainless steel. Electrically ground the inside surface of PM transfer lines.
(d) Optional sample-conditioning components for gaseous sampling. You may use the following sample-conditioning components to prepare gaseous samples for analysis, as long you do not install or use them in a way that adversely affects your ability to show that your engines comply with all applicable gaseous emission standards.
(1) NO2-to-NO converter. You may use an NO2-to-NO converter that meets the efficiency-performance check specified in §1065.378 at any point upstream of a NOX analyzer, sample bag, or other storage medium.
(2) Sample dryer. You may use either type of sample dryer described in this paragraph (d)(2) to decrease the effects of water on gaseous emission measurements. You may not use a chemical dryer, or used dryers upstream of PM sample filters.
(i) Osmotic-membrane. You may use an osmotic-membrane dryer upstream of any gaseous analyzer or storage medium, as long as it meets the temperature specifications in paragraph (c)(1) of this section. Because osmotic-membrane dryers may deteriorate after prolonged exposure to certain exhaust constituents, consult with the membrane manufacturer regarding your application before incorporating an osmotic-membrane dryer. Monitor the dewpoint, Tdew, and absolute pressure, ptotal, downstream of an osmotic-membrane dryer. You may use continuously recorded values of Tdew and ptotal in the amount of water calculations specified in §1065.645. If you do not continuously record these values, you may use their peak values observed during a test or their alarm setpoints as constant values in the calculations specified in §1065.645. You may also use a nominal ptotal, which you may estimate as the dryer's lowest absolute pressure expected during testing.
(ii) Thermal chiller. You may use a thermal chiller upstream of some gas analyzers and storage media. You may not use a thermal chiller upstream of a THC measurement system for compression-ignition engines, 2-stroke spark-ignition engines, or 4-stroke spark-ignition engines below 19 kW. If you use a thermal chiller upstream of an NO2-to-NO converter or in a sampling system without an NO2-to-NO converter, the chiller must meet the NO2 loss-performance check specified in §1065.376. Monitor the dewpoint, Tdew, and absolute pressure, ptotal, downstream of a thermal chiller. You may use continuously recorded values of Tdew and ptotal in the emission calculations specified in §1065.650. If you do not continuously record these values, you may use their peak values observed during a test or their high alarm setpoints as constant values in the amount of water calculations specified in §1065.645. You may also use a nominal ptotal, which you may estimate as the dryer's lowest absolute pressure expected during testing. If it is valid to assume the degree of saturation in the thermal chiller, you may calculate Tdew based on the known chiller efficiency and continuous monitoring of chiller temperature, Tchiller. If you do not continuously record values of Tchiller, you may use its peak value observed during a test, or its alarm setpoint, as a constant value to determine a constant amount of water according to §1065.645. If it is valid to assume that Tchiller is equal to Tdew, you may use Tchiller in lieu of Tdew according to §1065.645. If we ask for it, you must show by engineering analysis or by data the validity of any assumptions allowed by this paragraph (d)(2)(ii).
(3) Sample pumps. You may use sample pumps upstream of an analyzer or storage medium for any gas. Use sample pumps with inside surfaces of 300 series stainless steel, PTFE, or any other material that you demonstrate has better properties for emission sampling. For some sample pumps, you must control temperatures, as follows:
(i) If you use a NOX sample pump upstream of either an NO2-to-NO converter that meets §1065.378 or a chiller that meets §1065.376, it must be heated to prevent aqueous condensation.
(ii) For testing compression-ignition engines, 2-stroke spark-ignition engines, or 4-stroke compression ignition engines below 19 kW, if you use a THC sample pump upstream of a THC analyzer or storage medium, its inner surfaces must be heated to a tolerance of (191 ±11) °C.
(e) Optional sample-conditioning components for PM sampling. You may use the following sample-conditioning components to prepare PM samples for analysis, as long you do not install or use them in a way that adversely affects your ability to show that your engines comply with the applicable PM emission standards. You may condition PM samples to minimize positive and negative biases to PM results, as follows:
(1) PM preclassifier. You may use a PM preclassifier to remove large-diameter particles. The PM preclassifier may be either an inertial impactor or a cyclonic separator. It must be constructed of 300 series stainless steel. The preclassifier must be rated to remove at least 50% of PM at an aerodynamic diameter of 10 µm and no more than 1% of PM at an aerodynamic diameter of 1 µm over the range of flow rates for which you use it. Follow the preclassifier manufacturer's instructions for any periodic servicing that may be necessary to prevent a buildup of PM. Install the preclassifier in the dilution system downstream of the last dilution stage. Configure the preclassifier outlet with a means of bypassing any PM sample media so the preclassifier flow may be stabilized before starting a test. Locate PM sample media within 50 cm downstream of the preclassifier's exit. You may not use this preclassifier if you use a PM probe that already has a preclassifier. For example, if you use a hat-shaped preclassifier that is located immediately upstream of the probe in such a way that it forces the sample flow to change direction before entering the probe, you may not use any other preclassifier in your PM sampling system.
(2) Other components. You may request to use other PM conditioning components upstream of a PM preclassifier, such as components that condition humidity or remove gaseous-phase hydrocarbons from the diluted exhaust stream. You may use such components only if we approve them under §1065.10.
§ 1065.150 Continuous sampling.
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You may use continuous sampling techniques for measurements that involve raw or dilute sampling. Make sure continuous sampling systems meet the specifications in §1065.145. Make sure continuous analyzers meet the specifications in subparts C and D of this part.
§ 1065.170 Batch sampling for gaseous and PM constituents.
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Batch sampling involves collecting and storing emissions for later analysis. Examples of batch sampling include collecting and storing gaseous emissions in a bag and collecting and storing PM on a filter. You may use batch sampling to store emissions that have been diluted at least once in some way, such as with CVS, PFD, or BMD. You may use batch-sampling to store undiluted emissions only if we approve it as an alternate procedure under §1065.10.
(a) Sampling methods. For batch sampling, extract the sample at a rate proportional to the exhaust flow. If you extract from a constant-volume flow rate, sample at a constant-volume flow rate. If you extract from a varying flow rate, vary the sample rate in proportion to the varying flow rate. Validate proportional sampling after an emission test as described in §1065.545. Use storage media that do not change measured emission levels (either up or down). For example, do not use sample bags for storing emissions if the bags are permeable with respect to emissions or if they off-gas emissions. As another example, do not use PM filters that irreversibly absorb or adsorb gases.
(b) Gaseous sample storage media. Store gas volumes in sufficiently clean containers that minimally off-gas or allow permeation of gases. Use good engineering judgment to determine acceptable thresholds of storage media cleanliness and permeation. To clean a container, you may repeatedly purge and evacuate a container and you may heat it. Use a flexible container (such as a bag) within a temperature-controlled environment, or use a temperature controlled rigid container that is initially evacuated or has a volume that can be displaced, such as a piston and cylinder arrangement. Use containers meeting the specifications in the following table, noting that you may request to use other container materials under §1065.10:
Table 1 of § 1065.170_Gaseous Batch Sampling Container Materials
------------------------------------------------------------------------
Engines
-----------------------------------------
Compression-ignition,
Emissions two-stroke spark
ignition, 4-stroke All other
spark-ignition <19 engines
kW
------------------------------------------------------------------------
CO, CO2, O2, CH4, C2H6, C3H8, Tedlar\TM\, \2\ Tedlar\TM\, \2\
NO, NO2 \1\. Kynar\TM\, \2\ Kynar\TM\, \2\
Teflon\TM\, \3\ or Teflon\TM\, \3\
300 series stainless or 300 series
steel \3\. stainless steel
\3\
THC, NMHC..................... Teflon\TM\ \4\ or 300 Tedlar\TM\, \2\
series stainless Kynar\TM\, \2\
steel \4\. Teflon\TM\, \3\
or 300 series
stainless steel
\3\
------------------------------------------------------------------------
\1\ As long as you prevent aqueous condensation in storage container.
\2\ Up to 40 °C.
\3\ Up to 202 °C.
\4\ At (191 ±11) °C.
(c) PM sample media. Apply the following methods for sampling particulate emissions:
(1) If you use filter-based sampling media to extract and store PM for measurement, your procedure must meet the following specifications:
(i) If you expect that a filter's total surface concentration of PM will exceed 0.473 mm/mm 2 for a given test interval, you may use filter media with a minimum initial collection efficiency of 98%; otherwise you must use a filter media with a minimum initial collection efficiency of 99.7%. Collection efficiency must be measured as described in ASTM D 2986–95a (incorporated by reference in §1065.1010), though you may rely on the sample-media manufacturer's measurements reflected in their product ratings to show that you meet applicable requirements.
(ii) The filter must be circular, with an overall diameter of 46.50 ±0.6 mm and an exposed diameter of at least 38 mm. See the cassette specifications in paragraph (c)(1)(vi) of this section.
(iii) We highly recommend that you use a pure PTFE filter material that does not have any flow-through support bonded to the back and has an overall thickness of 40 ±20 µm. An inert polymer ring may be bonded to the periphery of the filter material for support and for sealing between the filter cassette parts. We consider Polymethylpentene (PMP) and PTFE inert materials for a support ring, but other inert materials may be used. See the cassette specifications in paragraph (c)(1)(v) of this section. We allow the use of PTFE-coated glass fiber filter material, as long as this filter media selection does not affect your ability to demonstrate compliance with the applicable standards, which we base on a pure PTFE filter material. Note that we will use pure PTFE filter material for compliance testing, and we may require you to use pure PTFE filter material for any compliance testing we require, such as for selective enforcement audits.
(iv) You may request to use other filter materials or sizes under the provisions of §1065.10.
(v) To minimize turbulent deposition and to deposit PM evenly on a filter, use a 12.5° (from center) divergent cone angle to transition from the transfer-line inside diameter to the exposed diameter of the filter face. Use 300 series stainless steel for this transition.
(vi) Maintain sample velocity at the filter face at or below 100 cm/s, where filter face velocity is the measured volumetric flow rate of the sample at the pressure and temperature upstream of the filter face, divided by the filter's exposed area.
(vii) Use a clean cassette designed to the specifications of Figure 1 of §1065.170 and made of any of the following materials: Delrin TM , 300 series stainless steel, polycarbonate, acrylonitrile-butadiene-styrene (ABS) resin, or conductive polypropylene. We recommend that you keep filter cassettes clean by periodically washing or wiping them with a compatible solvent applied using a lint-free cloth. Depending upon your cassette material, ethanol (C2H5OH) might be an acceptable solvent. Your cleaning frequency will depend on your engine's PM and HC emissions.
(viii) If you store filters in cassettes in an automatic PM sampler, cover or seal individual filter cassettes after sampling to prevent communication of semi-volatile matter from one filter to another.
(2) You may use other PM sample media that we approve under §1065.10, including non-filtering techniques. For example, you might deposit PM on an inert substrate that collects PM using electrostatic, thermophoresis, inertia, diffusion, or some other deposition mechanism, as approved.
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§ 1065.190 PM-stabilization and weighing environments for gravimetric analysis.
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(a) This section describes the two environments required to stabilize and weigh PM for gravimetric analysis: the PM stabilization environment, where filters are stored before weighing; and the weighing environment, where the balance is located. The two environments may share a common space. These volumes may be one or more rooms, or they may be much smaller, such as a glove box or an automated weighing system consisting of one or more countertop-sized environments.
(b) We recommend that you keep both the stabilization and the weighing environments free of ambient contaminants, such as dust, aerosols, or semi-volatile material that could contaminate PM samples. We recommend that these environments conform with an “as-built” Class Six clean room specification according to ISO 14644–1 (incorporated by reference in §1065.1010); however, we also recommend that you deviate from ISO 14644–1 as necessary to minimize air motion that might affect weighing. We recommend maximum air-supply and air-return velocities of 0.05 m/s in the weighing environment.
(c) Verify the cleanliness of the PM-stabilization environment using reference filters, as described in §1065.390(b).
(d) Maintain the following ambient conditions within the two environments during all stabilization and weighing:
(1) Ambient temperature and tolerances. Maintain the weighing environment at a tolerance of (22 ±1) °C. If the two environments share a common space, maintain both environments at a tolerance of (22 ±1) °C. If they are separate, maintain the stabilization environment at a tolerance of (22 ±3) °C.
(2) Dewpoint. Maintain a dewpoint of 9.5 °C in both environments. This dewpoint will control the amount of water associated with sulfuric acid (H2SO4) PM, such that 1.1368 grams of water will be associated with each gram of H2SO4.
(3) Dewpoint tolerances. If the expected fraction of sulfuric acid in PM is unknown, we recommend controlling dewpoint at within ±1 °C tolerance. This would limit any dewpoint-related change in PM to less than ±2%, even for PM that is 50% sulfuric acid. If you know your expected fraction of sulfuric acid in PM, we recommend that you select an appropriate dewpoint tolerance for showing compliance with emission standards using the following table as a guide:
Table 1 of § 1065.190_Dewpoint Tolerance as a Function of % PM Change and % Sulfuric Acid PM
----------------------------------------------------------------------------------------------------------------
Expected sulfuric acid fraction of PM ±0.5% PM mass ±1.0% PM mass ±2.0% PM mass
(percent) change change change
----------------------------------------------------------------------------------------------------------------
5..................................... ±3.0 °C..... ±6.0 °C..... ±12 °C
50.................................... ±0.30 °C.... ±0.60 °C.... ±1.2 °C
100................................... ±0.15 °C.... ±0.30 °C.... ±0.60 °C
----------------------------------------------------------------------------------------------------------------
(e) Verify the following ambient conditions using measurement instruments that meet the specifications in subpart C of this part:
(1) Continuously measure dewpoint and ambient temperature. Use these values to determine if the stabilization and weighing environments have remained within the tolerances specified in paragraph (d) of this section for at least the past 60 min. We recommend that you provide an interlock that automatically prevents the balance from reporting values if either of the environments have not been within the applicable tolerances for the past 60 min.
(2) Continuously measure atmospheric pressure within the weighing environment. You may use a shared atmospheric pressure meter as long as you can show that your equipment for handling the weighing environment air maintains ambient pressure at the balance within ±100 Pa of the shared atmospheric pressure. Provide a means to record the most recent atmospheric pressure when you weigh each PM sample. Use this value to calculate the PM buoyancy correction in §1065.690.
(f) We recommend that you install a balance as follows:
(1) Install the balance on a vibration-isolation platform to isolate it from external noise and vibration.
(2) Shield the balance from convective airflow with a static-dissipating draft shield that is electrically grounded.
(3) Follow the balance manufacturer's specifications for all preventive maintenance.
(4) Operate the balance manually or as part of an automated weighing system.
(g) Minimize static electric charge in the balance environment, as follows:
(1) Electrically ground the balance.
(2) Use 300 series stainless steel tweezers if PM samples must be handled manually.
(3) Ground tweezers with a grounding strap, or provide a grounding strap for the operator such that the grounding strap shares a common ground with the balance. Make sure grounding straps have an appropriate resistor to protect operators from accidental shock.
(4) Provide a static-electricity neutralizer that is electrically grounded in common with the balance to remove static charge from PM samples, as follows:
(i) You may use radioactive neutralizers such as a Polonium ( 210 Po) source. Replace radioactive sources at the intervals recommended by the neutralizer manufacturer.
(ii) You may use other neutralizers, such as corona-discharge ionizers. If you use a corona-discharge ionizer, we recommend that you monitor it for neutral net charge according to the ionizer manufacturer's recommendations.
(5) We recommend that you use a device to monitor the static charge of PM sample media surfaces.
(6) We recommend that you neutralize PM sample media to within ±2.0 V of neutral.
§ 1065.195 PM-stabilization environment for in-situ analyzers.
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(a) This section describes the environment required to determine PM in-situ. For in-situ analyzers, such as an inertial balance, this is the environment within a PM sampling system that surrounds the PM sample media. This is typically a very small volume.
(b) Maintain the environment free of ambient contaminants, such as dust, aerosols, or semi-volatile material that could contaminate PM samples. Filter all air used for stabilization with HEPA filters. Ensure that HEPA filters are installed properly so that background PM does not leak past the HEPA filters.
(c) Maintain the following thermodynamic conditions within the environment before measuring PM:
(1) Ambient temperature. Select a nominal ambient temperature, Tamb, between (42 and 52) °C. Maintain the ambient temperature within ±1.0 °C of the selected nominal value.
(2) Dewpoint. Select a dewpoint, Tdew, that corresponds to Tamb such that Tdew = (0.95Tamb-11.40) °C. The resulting dewpoint will control the amount of water associated with sulfuric acid (H2SO4) PM, such that 1.1368 grams of water will be associated with each gram of H2SO4. For example, if you select a nominal ambient temperature of 47 °C, set a dewpoint of 33.3 °C.
(3) Dewpoint tolerance. If the expected fraction of sulfuric acid in PM is unknown, we recommend controlling dewpoint within ±1.0 °C. This would limit any dewpoint-related change in PM to less than ±2%, even for PM that is 50% sulfuric acid. If you know your expected fraction of sulfuric acid in PM, we recommend that you select an appropriate dewpoint tolerance for showing compliance with emission standards using Table 1 of §1065.190 as a guide:
(4) Absolute pressure. Maintain an absolute pressure of (80.000 to 103.325) kPa. Use good engineering judgment to maintain a more stringent tolerance of absolute pressure if your PM measurement instrument requires it.
(d) Continuously measure dewpoint, temperature, and pressure using measurement instruments that meet the PM-stabilization environment specifications in subpart C of this part. Use these values to determine if the in-situ stabilization environment is within the tolerances specified in paragraph (c) of this section. Do not use any PM quantities that are recorded when any of these parameters exceed the applicable tolerances.
(e) If you use an inertial PM balance, we recommend that you install it as follows:
(1) Isolate the balance from any external noise and vibration that is within a frequency range that could affect the balance.
(2) Follow the balance manufacturer's specifications.
(f) If static electricity affects an inertial balance, you may use a static neutralizer, as follows:
(1) You may use a radioactive neutralizer such as a Polonium ( 210 Po) source or a Krypton ( 85 Kr) source. Replace radioactive sources at the intervals recommended by the neutralizer manufacturer.
(2) You may use other neutralizers, such as a corona-discharge ionizer. If you use a corona-discharge ionizer, we recommend that you monitor it for neutral net charge according to the ionizer manufacturer's recommendations.
Subpart C—Measurement Instruments
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§ 1065.201 Overview and general provisions.
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(a) Scope. This subpart specifies measurement instruments and associated system requirements related to emission testing in a laboratory and in the field. This includes laboratory instruments and portable emission measurement systems (PEMS) for measuring engine parameters, ambient conditions, flow-related parameters, and emission concentrations.
(b) Instrument types. You may use any of the specified instruments as described in this subpart to perform emission tests. If you want to use one of these instruments in a way that is not specified in this subpart, or if you want to use a different instrument, you must first get us to approve your alternate procedure under §1065.10. Where we specify more than one instrument for a particular measurement, we may identify which instrument serves as the reference for showing that an alternative procedure is equivalent to the specified procedure.
(c) Measurement systems. Assemble a system of measurement instruments that allows you to show that your engines comply with the applicable emission standards, using good engineering judgment. When selecting instruments, consider how conditions such as vibration, temperature, pressure, humidity, viscosity, specific heat, and exhaust composition (including trace concentrations) may affect instrument compatibility and performance.
(d) Redundant systems. For all measurement instruments described in this subpart, you may use data from multiple instruments to calculate test results for a single test. If you use redundant systems, use good engineering judgment to use multiple measured values in calculations or to disregard individual measurements. Note that you must keep your results from all measurements, as described in §1065.25. This requirements applies whether or not you actually use the measurements in your calculations.
(e) Range. You may use an instrument's response above 100% of its operating range if this does not affect your ability to show that your engines comply with the applicable emission standards. Note that we require additional testing and reporting if an analyzer responds above 100% of its range. See §1065.550. Auto-ranging analyzers do not require additional testing or reporting.
(f) Related subparts for laboratory testing. Subpart D of this part describes how to evaluate the performance of the measurement instruments in this subpart. In general, if an instrument is specified in a specific section of this subpart, its calibration and verifications are typically specified in a similarly numbered section in subpart D of this part. For example, §1065.290 gives instrument specifications for PM balances and §1065.390 describes the corresponding calibrations and verifications. Note that some instruments also have other requirements in other sections of subpart D of this part. Subpart B of this part identifies specifications for other types of equipment, and subpart H of this part specifies engine fluids and analytical gases.
(g) Field testing and testing with PEMS. Subpart J of this part describes how to use these and other measurement instruments for field testing and other PEMS testing.
§ 1065.202 Data updating, recording, and control.
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Your test system must be able to update data, record data and control systems related to operator demand, the dynamometer, sampling equipment, and measurement instruments. Use data acquisition and control systems that can record at the specified minimum frequencies, as follows:
Table 1 of § 1065.202_Data Recording and Control Minimum Frequencies
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Minimum command and Minimum recording
Applicable test protocol section Measured values control frequency frequency
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§ 1065.510.................... Speed and torque during an 1 Hz.................. 1 mean value per step.
engine step-map.
§ 1065.510.................... Speed and torque during an 5 Hz.................. 1 Hz means.
engine sweep-map.
§ 1065.514, § 1065.530... Transient duty cycle 5 Hz.................. 1 Hz means.
reference and feedback
speeds and torques.
§ 1065.514, § 1065.530... Steady-state and ramped- 1 Hz.................. 1 Hz.
modal duty cycle reference
and feedback speeds and
torques.
§ 1065.520, § 1065.530, Continuous concentrations N/A................... 1 Hz.
§ 1065.550. of raw or dilute analyzers.
§ 1065.520, § 1065.530, Batch concentrations of raw N/A................... 1 mean value per test
§ 1065.550. or dilute analyzers. interval.
§ 1065.530, § 1065.545... Diluted exhaust flow rate N/A................... 1 Hz.
from a CVS with a heat
exchanger upstream of the
flow measurement.
§ 1065.530, § 1065.545... Diluted exhaust flow rate 5 Hz.................. 1 Hz means.
from a CVS without a heat
exchanger upstream of the
flow measurement.
§ 1065.530, § 1065.545... Intake-air or raw-exhaust N/A................... 1 Hz means.
flow rate.
§ 1065.530, § 1065.545... Dilution air if actively 5 Hz.................. 1 Hz means.
controlled.
§ 1065.530.................... Sample flow from a CVS that 1 Hz.................. 1 Hz.
has a heat exchanger.
§ 1065.530, § 1065.545... Sample flow from a CVS does 5 Hz.................. 1 Hz mean.
not have a heat exchanger.
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§ 1065.205 Performance specifications for measurement instruments.
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Your test system as a whole must meet all the applicable calibrations, verifications, and test-validation criteria specified in subparts D and F of this part or subpart J of this part for using PEMS and for performing field testing. We recommend that your instruments meet the specifications in Table 1 of this section for all ranges you use for testing. We also recommend that you keep any documentation you receive from instrument manufacturers showing that your instruments meet the specifications in Table 1 of this section.
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Measurement of Engine Parameters and Ambient Conditions
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§ 1065.210 Work input and output sensors.
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(a) Application. Use instruments as specified in this section to measure work inputs and outputs during engine operation. We recommend that you use sensors, transducers, and meters that meet the specifications in Table 1 of §1065.205. Note that your overall systems for measuring work inputs and outputs must meet the linearity verifications in §1065.307. We recommend that you measure work inputs and outputs where they cross the system boundary as shown in Figure 1 of this section. The system boundary is different for air-cooled engines than for liquid-cooled engines. If you choose to measure work before or after a work conversion, relative to the system boundary, use good engineering judgment to estimate any work-conversion losses in a way that avoids overestimation of total work. For example, if it is impractical to instrument the shaft of an exhaust turbine generating electrical work, you may decide to measure its converted electrical work. In this case, divide the electrical work by an accurate value of electrical generator efficiency (?<1), or assume an efficiency of 1 (?=1), which would over-estimate brake-specific emissions. Do not underestimate the generator's efficiency because this would result in an under-estimation of brake-specific emissions. In all cases, ensure that you are able to accurately demonstrate compliance with the applicable standards.
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(b) Shaft work. Use speed and torque transducer outputs to calculate total work according to §1065.650.
(1) Speed. Use a magnetic or optical shaft-position detector with a resolution of at least 60 counts per revolution, in combination with a frequency counter that rejects common-mode noise.
(2) Torque. You may use a variety of methods to determine engine torque. As needed, and based on good engineering judgment, compensate for torque induced by the inertia of accelerating and decelerating components connected to the flywheel, such as the drive shaft and dynamometer rotor. Use any of the following methods to determine engine torque:
(i) Measure torque by mounting a strain gage or similar instrument in-line between the engine and dynamometer.
(ii) Measure torque by mounting a strain gage or similar instrument on a lever arm connected to the dynamometer housing.
(iii) Calculate torque from internal dynamometer signals, such as armature current, as long as you calibrate this measurement as described in §1065.310.
(c) Electrical work. Use a watt-hour meter output to calculate total work according to §1065.650. Use a watt-hour meter that outputs active power (kW). Watt-hour meters typically combine a Wheatstone bridge voltmeter and a Hall-effect clamp-on ammeter into a single microprocessor-based instrument that analyzes and outputs several parameters, such as alternating or direct current voltage (V), current (A), power factor (pf), apparent power (VA), reactive power (VAR), and active power (W).
(d) Pump, compressor or turbine work. Use pressure transducer and flow-meter outputs to calculate total work according to §1065.650. For flow meters, see §1065.220 through §1065.248.
§ 1065.215 Pressure transducers, temperature sensors, and dewpoint sensors.
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(a) Application. Use instruments as specified in this section to measure pressure, temperature, and dewpoint.
(b) Component requirements. We recommend that you use pressure transducers, temperature sensors, and dewpoint sensors that meet the specifications in Table 1 of §1065.205. Note that your overall systems for measuring pressure, temperature, and dewpoint must meet the calibration and verifications in §1065.315.
(c) Temperature. For PM-balance environments or other precision temperature measurements over a narrow temperature range, we recommend thermistors. For other applications we recommend thermocouples that are not grounded to the thermocouple sheath. You may use other temperature sensors, such as resistive temperature detectors (RTDs).
(d) Pressure. Pressure transducers must be located in a temperature-controlled environment, or they must compensate for temperature changes over their expected operating range. Transducer materials must be compatible with the fluid being measured. For atmospheric pressure or other precision pressure measurements, we recommend either capacitance-type, quartz crystal, or laser-interferometer transducers. For other applications, we recommend either strain gage or capacitance-type pressure transducers. You may use other pressure-measurement instruments, such as manometers, where appropriate.
(e) Dewpoint. For PM-stabilization environments, we recommend chilled-surface hygrometers. For other applications, we recommend thin-film capacitance sensors. You may use other dewpoint sensors, such as a wet-bulb/dry-bulb psychrometer, where appropriate.
Flow-Related Measurements
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§ 1065.220 Fuel flow meter.
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(a) Application. You may use fuel flow in combination with a chemical balance of carbon (or oxygen) between the fuel, inlet air, and raw exhaust to calculate raw exhaust flow as described in §1065.650, as follows:
(1) Use the actual value of calculated raw exhaust flow rate in the following cases:
(i) For multiplying raw exhaust flow rate with continuously sampled concentrations.
(ii) For multiplying total raw exhaust flow with batch-sampled concentrations.
(2) In the following cases, you may use a fuel flow meter signal that does not give the actual value of raw exhaust, as long as it is linearly proportional to the exhaust molar flow rate's actual calculated value:
(i) For feedback control of a proportional sampling system, such as a partial-flow dilution system.
(ii) For multiplying with continuously sampled gas concentrations, if the same signal is used in a chemical-balance calculation to determine work from brake-specific fuel consumption and fuel consumed.
(b) Component requirements. We recommend that you use a fuel flow meter that meets the specifications in Table 1 of §1065.205. We recommend a fuel flow meter that measures mass directly, such as one that relies on gravimetric or inertial measurement principles. This may involve using a meter with one or more scales for weighing fuel or using a Coriolis meter. Note that your overall system for measuring fuel flow must meet the linearity verification in §1065.307 and the calibration and verifications in §1065.320. (continued)