(a) General. For all emission measurements, use test fuels that meet the specifications in this subpart, unless the standard-setting part directs otherwise. Section 1065.10(c)(1) does not apply with respect to test fuels. Note that the standard-setting parts generally require that you design your emission controls to function properly when using commercially available fuels, even if they differ from the test fuel. Where we specify multiple grades of a certain fuel type (such as diesel fuel with different sulfur concentrations), see the standard-setting part to determine which grade to use.

(b) Fuels meeting alternate specifications. We may allow you to use a different test fuel (such as California LEV III gasoline) if it does not affect your ability to show that your engines would comply with all applicable emission standards in this chapter using the test fuel specified in this subpart.

(c) Fuels not specified in this subpart. If you produce engines that run on a type of fuel (or mixture of fuels) that we do not specify in this subpart, you must get our written approval to establish the appropriate test fuel. See the standard-setting part for provisions related to fuels and fuel mixtures not specified in this subpart.

(1) For engines designed to operate on a single fuel, we will generally allow you to use the fuel if you show us all the following things are true:

(i) Show that your engines will use only the designated fuel in service.

(ii) Show that this type of fuel is commercially available.

(iii) Show that operating the engines on the fuel we specify would be inappropriate, as in the following examples:

(A) The engine will not run on the specified fuel.

(B) The engine or emission controls will not be durable or work properly when operating with the specified fuel.

(C) The measured emission results would otherwise be substantially unrepresentative of in-use emissions.

(2) For engines that are designed to operate on different fuel types, the provisions of paragraphs (c)(1)(ii) and (iii) of this section apply with respect to each fuel type.

(3) For engines that are designed to operate on different fuel types as well as continuous mixtures of those fuels, we may require you to test with either the worst-case fuel mixture or the most representative fuel mixture, unless the standard-setting part specifies otherwise.

(d) Fuel specifications. Specifications in this section apply as follows:

(1) Measure and calculate values as described in the appropriate reference procedure. Record and report final values expressed to at least the same number of decimal places as the applicable limit value. The right-most digit for each limit value is significant unless specified otherwise. For example, for a specified distillation temperature of 60 °C, determine the test fuel's value to at least the nearest whole number.

(2) The fuel parameters specified in this subpart depend on measurement procedures that are incorporated by reference. For any of these procedures, you may instead rely upon the procedures identified in 40 CFR part 1090 for measuring the same parameter. For example, we may identify different reference procedures for measuring gasoline parameters in 40 CFR 1090.1360.

(e) Two-stroke fuel/oil mixing. For two-stroke engines, use a fuel/oil mixture meeting the manufacturer's specifications.

(f) Service accumulation and field testing fuels. If we do not specify a service-accumulation or field-testing fuel in the standard-setting part, use an appropriate commercially available fuel such as those meeting minimum specifications from the following table:

[70 FR 40516, July 13, 2005, as amended at 73 FR 37339, June 30, 2008; 73 FR 59341, Oct. 8, 2008; 75 FR 23057, Apr. 30, 2010;79 FR 23807, Apr. 28, 2014; 85 FR 78468, Dec. 4, 2020; 86 FR 34568, June 29, 2021]

(a) Distillate diesel fuels for testing must be clean and bright, with pour and cloud points adequate for proper engine operation.

(b) There are three grades of #2 diesel fuel specified for use as a test fuel. See the standard-setting part to determine which grade to use. If the standard-setting part does not specify which grade to use, use good engineering judgment to select the grade that represents the fuel on which the engines will operate in use. The three grades are specified in Table 1 of this section.

(c) You may use the following nonmetallic additives with distillate diesel fuels:

(1) Cetane improver.

(2) Metal deactivator.

(3) Antioxidant, dehazer.

(4) Rust inhibitor.

(5) Pour depressant.

(6) Dye.

(7) Dispersant.

(8) Biocide.

[70 FR 40516, July 13, 2005, as amended at 73 FR 37340, June 30, 2008; 73 FR 59341, Oct. 8, 2008; 75 FR 23057, Apr. 30, 2010; 77 FR 2464, Jan. 18, 2012;79 FR 23807, Apr. 28, 2014; 85 FR 78468, Dec. 4, 2020; 86 FR 34569, June 29, 2021]

This section describes the specifications for fuels meeting the definition of residual fuel in 40 CFR 1090.80, including fuels marketed as intermediate fuel. Residual fuels for service accumulation and any testing must meet the following specifications:

(a) The fuel must be a commercially available fuel that is representative of the fuel that will be used by the engine in actual use.

(b) The fuel must be free of used lubricating oil. Demonstrate this by showing that the fuel meets at least one of the following specifications.

(1) Zinc is at or below 15 mg per kg of fuel based on the procedures specified in IP—470, IP—501, or ISO 8217 (incorporated by reference, see § 1065.1010).

(2) Phosphorus is at or below 15 mg per kg of fuel based on the procedures specified in IP—500, IP—501, or ISO 8217 (incorporated by reference, see § 1065.1010).

(3) Calcium is at or below 30 mg per kg of fuel based on the procedures specified in IP—470, IP—501, or ISO 8217 (incorporated by reference, see § 1065.1010).

(c) The fuel must meet the specifications for one of the categories in the following table:

[79 FR 23808, Apr. 28, 2014, as amended at 85 FR 78468, Dec. 4, 2020; 86 FR 34569, June 29, 2021; 89 FR 29823, Apr. 22, 2024]

(a) This section specifies test fuel properties for gasoline with ethanol (low-level blend only) and for gasoline without ethanol. Note that the “fuel type” for the fuels specified in paragraphs (b) and (c) of this section is considered to be gasoline. In contrast, fuels with higher ethanol concentrations, such as fuel containing 82 percent ethanol, are considered to be ethanol fuels rather than gasoline. We specify some test fuel parameters that apply uniquely for low-temperature testing and for testing at altitudes above 1,219 m. For all other testing, use the test fuel parameters specified for general testing. Unless the standard-setting part specifies otherwise, use the fuel specified in paragraph (c) of this section for general testing.

(b) The following specifications apply for a blended gasoline test fuel that has nominally 10% ethanol (commonly called E10 test fuel):

(1) Prepare the blended test fuel from typical refinery gasoline blending components. You may not use pure compounds, except as follows:

(i) You may use neat ethanol as a blendstock.

(ii) You may adjust the test fuel's vapor pressure by adding butane.

(iii) You may adjust the test fuel's benzene content by adding benzene.

(iv) You may adjust the test fuel's sulfur content by adding sulfur compounds that are representative of those found with in-use fuels.

(2) Table 1 of this section identifies limit values consistent with the units in the reference procedure for each fuel property. These values are generally specified in international units. Values presented in parentheses are for information only. Table 1 follows:

(3) The ethanol-blended specification in Table 1 of this section is based on the volume % ethanol content of the fuel as determined during blending by the fuel supplier and as stated by the supplier at the time of fuel delivery. Use good engineering judgment to determine the volume % of ethanol based on the volume of each blendstock. We recommend using a flow-based or gravimetric procedure that has an accuracy and repeatability of ±0.1%.

(c) The specifications of this paragraph (c) apply for testing with neat gasoline. This is sometimes called indolene or E0 test fuel. Gasoline for testing must have octane values that represent commercially available fuels for the appropriate application. Test fuel specifications apply as follows:

(d) Use the high-octane gasoline specified in paragraph (b) of this section only for engines or vehicles for which the manufacturer conditions the warranty on the use of premium gasoline.

[79 FR 23809, Apr. 28, 2014, as amended at 80 FR 9119, Feb. 19, 2015; 86 FR 34571, June 29, 2021]

(a) Except as specified in paragraph (b) of this section, natural gas for testing must meet the specifications in the following table:

(b) In certain cases you may use test fuel not meeting the specifications in paragraph (a) of this section, as follows:

(1) You may use fuel that your in-use engines normally use, such as pipeline natural gas.

(2) You may use fuel meeting alternate specifications if the standard-setting part allows it.

(3) You may ask for approval to use fuel that does not meet the specifications in paragraph (a) of this section, but only if using the fuel would not adversely affect your ability to demonstrate compliance with the applicable standards in this chapter.

(c) When we conduct testing using natural gas, we will use fuel that meets the specifications in paragraph (a) of this section.

(d) At ambient conditions, natural gas must have a distinctive odor detectable down to a concentration in air not more than one-fifth the lower flammable limit.

[73 FR 37342, June 30, 2008, as amended at 79 FR 23811, Apr. 28, 2014; 86 FR 34573, June 29, 2021; 88 FR 4687, Jan. 24, 2023; 89 FR 29823, Apr. 22, 2024]

(a) Except as specified in paragraph (b) of this section, liquefied petroleum gas for testing must meet the specifications in the following table:

(b) In certain cases you may use test fuel not meeting the specifications in paragraph (a) of this section, as follows:

(1) You may use fuel that your in-use engines normally use, such as commercial-quality liquefied petroleum gas.

(2) You may use fuel meeting alternate specifications if the standard-setting part allows it.

(3) You may ask for approval to use fuel that does not meet the specifications in paragraph (a) of this section, but only if using the fuel would not adversely affect your ability to demonstrate compliance with the applicable standards in this chapter.

(c) When we conduct testing using liquefied petroleum gas, we will use fuel that meets the specifications in paragraph (a) of this section.

(d) At ambient conditions, liquefied petroleum gas must have a distinctive odor detectable down to a concentration in air not more than one-fifth the lower flammable limit.

[73 FR 37342, June 30, 2008, as amended at 79 FR 23811, Apr. 28, 2014; 86 FR 34573, June 29, 2021; 88 FR 4687, Jan. 24, 2023]

For testing vehicles capable of operating on a high-level ethanol-gasoline blend, create a test fuel as follows:

(a) Add ethanol to an E10 fuel meeting the specifications described in § 1065.710 until the ethanol content of the blended fuel is between 80 and 83 volume %.

(b) You may alternatively add ethanol to a gasoline base fuel with no ethanol if you can demonstrate that such a base fuel blended with the proper amount of ethanol would meet all the specifications for E10 test fuel described in § 1065.710, other than the ethanol content.

(c) The ethanol used for blending must be either denatured fuel ethanol meeting the specifications in 40 CFR 1090.270, or fuel-grade ethanol with no denaturant. Account for the volume of any denaturant when calculating volumetric percentages.

(d) The blended test fuel must have a dry vapor pressure equivalent between 41.5 and 45.1 kPa (6.0 and 6.5 psi) when measured using the procedure specified in § 1065.710. You may add commercial grade butane as needed to meet this specification.

[79 FR 23811, Apr. 28, 2014, as amended at 85 FR 78468, Dec. 4, 2020]

(a) Use commercially available diesel exhaust fluid that represents the product that will be used in your in-use engines.

(b) Diesel exhaust fluid for testing must generally conform to the specifications referenced in the definition of “diesel exhaust fluid” in § 1065.1001. Use marine-grade diesel exhaust fluid only for marine engines.

[81 FR 74191, Oct. 25, 2016]

(a) Use commercially available lubricating oil that represents the oil that will be used in your engine in use.

(b) You may use lubrication additives, up to the levels that the additive manufacturer recommends.

(a) You may use commercially available antifreeze mixtures or other coolants that will be used in your engine in use.

(b) For laboratory testing of liquid-cooled engines, you may use water with or without rust inhibitors.

(c) For coolants allowed in paragraphs (a) and (b) of this section, you may use rust inhibitors and additives required for lubricity, up to the levels that the additive manufacturer recommends.

Analytical gases must meet the accuracy and purity specifications of this section, unless you can show that other specifications would not affect your ability to show that you comply with all applicable emission standards.

(a) Subparts C, D, F, and J of this part refer to the following gas specifications:

(1) Use purified gases to zero measurement instruments and to blend with calibration gases. Use gases with contamination no higher than the highest of the following values in the gas cylinder or at the outlet of a zero-gas generator:

(i) 2% contamination, measured relative to the flow-weighted mean concentration expected at the standard. For example, if you would expect a flow-weighted CO concentration of 100.0 µmol/mol, then you would be allowed to use a zero gas with CO contamination less than or equal to 2.000 µmol/mol.

(ii) Contamination as specified in the following table:

(2) Use the following gases with a FID analyzer:

(i) FID fuel. Use FID fuel with a stated H2 concentration of (0.39 to 0.41) mol/mol, balance He or N2, and a stated total hydrocarbon concentration of 0.05 µmol/mol or less. For GC-FIDs that measure methane (CH4) using a FID fuel that is balance N2, perform the CH4 measurement as described in SAE J1151 (incorporated by reference, see § 1065.1010).

(ii) FID burner air. Use FID burner air that meets the specifications of purified air in paragraph (a)(1) of this section. For field testing, you may use ambient air.

(iii) FID zero gas. Zero flame-ionization detectors with purified gas that meets the specifications in paragraph (a)(1) of this section, except that the purified gas O2 concentration may be any value. Note that FID zero balance gases may be any combination of purified air and purified nitrogen. We recommend FID analyzer zero gases that contain approximately the expected flow-weighted mean concentration of O2 in the exhaust sample during testing.

(iv) FID propane span gas. Span and calibrate THC FID with span concentrations of propane, C3H8. Calibrate on a carbon number basis of one (C1). For example, if you use a C3H8 span gas of concentration 200 µmol/mol, span a FID to respond with a value of 600 µmol/mol. Note that FID span balance gases may be any combination of purified air and purified nitrogen. We recommend FID analyzer span gases that contain approximately the flow-weighted mean concentration of O2 expected during testing. If the expected O2 concentration in the exhaust sample is zero, we recommend using a balance gas of purified nitrogen.

(v) FID CH4 span gas. If you always span and calibrate a CH4 FID with a nonmethane cutter, then span and calibrate the FID with span concentrations of CH4. Calibrate on a carbon number basis of one (C1). For example, if you use a CH4 span gas of concentration 200 µmol/mol, span a FID to respond with a value of 200 µmol/mol. Note that FID span balance gases may be any combination of purified air and purified nitrogen. We recommend FID analyzer span gases that contain approximately the expected flow-weighted mean concentration of O2 in the exhaust sample during testing. If the expected O2 concentration in the exhaust sample is zero, we recommend using a balance gas of purified nitrogen.

(3) Use the following gas mixtures, with gases traceable within ±1% of the NIST-accepted gas standard value or other gas standards we approve:

(i) CH4, balance purified air and/or N2 (as applicable).

(ii) C2H6, balance purified air and/or N2 (as applicable).

(iii) C3H8, balance purified air and/or N2 (as applicable).

(iv) CO, balance purified N2.

(v) CO2, balance purified N2.

(vi) NO, balance purified N2.

(vii) NO2, balance purified air.

(viii) O2, balance purified N2.

(ix) C3H8, CO, CO2, NO, balance purified N2.

(x) C3H8, CH4, CO, CO2, NO, balance purified N2.

(xi) N2O, balance purified air and/or N2 (as applicable).

(xii) CH4, C2H6, balance purified air and/or N2 (as applicable).

(xiii) CH4, CH2O2, C2H2, C2H4, C2H4O, C2H6, C3H8, C3H6, CH4O, and C4H10. You may omit individual gas constituents from this gas mixture. If your gas mixture contains oxygenated hydrocarbons, your gas mixture must be in balance purified N2, otherwise you may use balance purified air.

(4) You may use gases for species other than those listed in paragraph (a)(3) of this section (such as methanol in air, which you may use to determine response factors), as long as they are traceable to within ±3% of the NIST-accepted value or other similar standards we approve, and meet the stability requirements of paragraph (b) of this section.

(5) You may generate your own calibration gases using a precision blending device, such as a gas divider, to dilute gases with purified N2 or purified air. If your gas divider meets the specifications in § 1065.248, and the gases being blended meet the requirements of paragraphs (a)(1) and (3) of this section, the resulting blends are considered to meet the requirements of this paragraph (a).

(6) If you measure H2O using an FTIR analyzer, generate H2O calibration gases with a humidity generator using one of the options in this paragraph (a)(6). Use good engineering judgment to prevent condensation in the transfer lines, fittings, or valves from the humidity generator to the FTIR analyzer. Design your system so the wall temperatures in the transfer lines, fittings, and valves from the point where the mole fraction of H2O in the humidified calibration gas, xH2Oref, is measured to the analyzer are at a temperature of (110 to 202) °C. Calibrate the humidity generator upon initial installation, within 370 days before verifying the H2O measurement of the FTIR, and after major maintenance. Use the uncertainties from the calibration of the humidity generator's measurements and follow NIST Technical Note 1297 (incorporated by reference, see § 1065.1010) to verify that the amount of H2O in the calibration gas, xH2Oref, is determined within ±3% uncertainty, UxH2O. If the humidity generator requires assembly before use, after assembly follow the instrument manufacturer's instructions to check for leaks. You may generate the H2O calibration gas using one of the following options:

(i) Bubble gas that meets the requirements of paragraph (a)(1) of this section through distilled H2O in a sealed vessel. Adjust the amount of H2O in the calibration gas by changing the temperature of the H2O in the sealed vessel. Determine absolute pressure, pabs, and dewpoint, Tdew, of the humidified gas leaving the sealed vessel. Calculate the amount of H2O in the calibration gas as described in § 1065.645(a) and (b). Calculate the uncertainty of the amount of H2O in the calibration gas, UxH2O, using the following equations:

Eq. 1065.750-1 Eq. 1065.750-2 Eq. 1065.750-3 Where: Tdew = saturation temperature of water at measured conditions. UTdew = expanded uncertainty (k = 2) of the measured saturation temperature of water at measured conditions. pabs = wet static absolute pressure at the location of the dewpoint measurement. UPabs = expanded uncertainty (k = 2) of the wet static absolute pressure at the location of the dewpoint measurement.

Example:

Tdew = 39.5 °C = 312.65 K UTdew = 0.390292 K pabs = 99.980 kPa UPabs = 1.15340 kPa

Using Eq. 1065.645-1,

xH2O = 0.0718436 mol/mol

(ii) Use a device that introduces a measured flow of distilled H2O as vapor into a measured flow of gas that meets the requirements of paragraph (a)(1) of this section. Determine the molar flows of gas and H2O that are mixed to generate the calibration gas.

(A) Calculate the amount of H2O in the calibration gas as follows:

Eq. 1065.750-4

(B) Calculate the uncertainty of the amount of H2O in the generated calibration gas, UxH2O, using the following equations:

Eq. 1065.750-5 Eq. 1065.750-6 Eq. 1065.750-7 Where: n gas = molar flow of gas entering the humidity generator. Un gas = expanded uncertainty (k=2) of the molar flow of gas entering the humidity generator. n H2O = molar flow of H2O entering the humidity generator, mol/s. Un H2O = expanded uncertainty (k=2) of the molar flow of H2O entering the humidity generator. xH2O = amount of H2O in the calibration gas. UXH2O = expanded uncertainty (k=2) of the amount of H2O in the generated calibration gas.

(C) The following example is a solution for using the equations in paragraph (a)(6)(ii)(B) of this section:

n H2O = 0.00138771 mol/s Un gas = 0.000226137 mol/s n gas = 0.0148680 mol/s Un H2O = 0.0000207436 mol/s

(b) Record the concentration of any calibration gas standard and its expiration date specified by the gas supplier.

(1) Do not use any calibration gas standard after its expiration date, except as allowed by paragraph (b)(2) of this section.

(2) Calibration gases may be relabeled and used after their expiration date as follows:

(i) Alcohol/carbonyl calibration gases used to determine response factors according to subpart I of this part may be relabeled as specified in subpart I of this part.

(ii) Other gases may be relabeled and used after the expiration date only if we approve it in advance.

(c) Transfer gases from their source to analyzers using components that are dedicated to controlling and transferring only those gases. For example, do not use a regulator, valve, or transfer line for zero gas if those components were previously used to transfer a different gas mixture. We recommend that you label regulators, valves, and transfer lines to prevent contamination. Note that even small traces of a gas mixture in the dead volume of a regulator, valve, or transfer line can diffuse upstream into a high-pressure volume of gas, which would contaminate the entire high-pressure gas source, such as a compressed-gas cylinder.

(d) To maintain stability and purity of gas standards, use good engineering judgment and follow the gas standard supplier's recommendations for storing and handling zero, span, and calibration gases. For example, it may be necessary to store bottles of condensable gases in a heated environment.

[70 FR 40516, July 13, 2005, as amended at 73 FR 37343, June 30, 2008; 74 FR 56518, Oct. 30, 2009; 75 FR 68465, Nov. 8, 2010; 76 FR 57467, Sept. 15, 2011; 79 FR 23811, Apr. 28, 2014; 81 FR 74191, Oct. 25, 2016; 86 FR 34574, June 29, 2021; 89 FR 29823, Apr. 22, 2024; 89 FR 51238, June 17, 2024]

(a) PM balance calibration weights. Use PM balance calibration weights that are certified as NIST-traceable within ±0.1% uncertainty. Make sure your highest calibration weight has no more than ten times the mass of an unused PM-sample medium.

(b) Dynamometer, fuel mass scale, and DEF mass scale calibration weights. Use dynamometer and mass scale calibration weights that are certified as NIST-traceable within ±0.1% uncertainty.

[88 FR 4687, Jan. 24, 2023]