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UN R49 Supplement 7 (06 series) · UNECE Regulation No. 49 (ECE R49) — Uniform provisions concerning the measures to be taken against the emission of gaseous and particulate pollutants from compression-ignition engines and positive ignition engines for use in vehicles.

UN R49 — Supplement 7 to the 06 series of amendments

Supplement 6 → 7

Adopted at the WP.29 185th sessionEntry into force 2022-06-22
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What changed
  • The SSV equations change: A0 is now 0.005692 and is divided by 60, and A1 is now 27.43831.
  • The linearity table adds a row for the humidity measurement device.
  • The FID burner fuel can now use nitrogen as an alternative to helium as the balance gas.
Why
  • In the volume flow equation, the coefficient A0 must be divided by 60, and the throat diameter dV must be in mm.
  • The regulation had no linearity requirements for humidity sensors, but the humidity of the intake air is an essential measure for the emission calculation.
  • OICA explained that helium is now difficult and expensive to acquire.

Q1What changed23 changes

Brackets in equations (36) and (37) (paras. 8.4.2.3. and 8.4.2.4.)

In equations (36) and (37), the product after the sum sign is now in brackets. The unit note now reads “in (g/test)” instead of “(in g/test)”.

\\displaystyle m_{\mathrm{gas}} = u_{gas} \times \sum_{i=1}^{i=n} c_\left(c_{\mathrm{gas,i}} \times q_{m\mathrm{ew,i}} \times \frac{1}{f} }\right) \quad \text{(in text{in (g/test)}\qquad\text{(36)}
\\displaystyle m_{\mathrm{gas}} = \sum_{i=1}^{i=n} u_\left(u_{\mathrm{gas,i}} \times c_{\mathrm{gas,i}} \times q_{m\mathrm{ew,i}} \times \frac{1}{f} }\right) \quad \text{(in g/test)}\text{in } \left(\frac{\mathrm{g}}{\mathrm{test}}\right)\qquad\text{(37)}

SSV equations and the constants A0 and A1 (paras. 8.5.1.4. and 9.5.4.1.)

Equation (54) now uses A0/60 instead of A0. Equation (89) for the discharge coefficient Cd now includes A0/60. Equation (90) for the Reynolds number Re now includes a factor of 60. A0 is now 0.005692 instead of 0.006111. A1 is now 27.43831 instead of 25.55152, and its SI units now include kg. Two definitions of the SSV throat diameter dV now give mm instead of m.

\\displaystyle Q_{\mathrm{SSV}} = A_{0}d_\frac{A_{0}}{60}d_{\mathrm{V}}^{2}C_{\mathrm{d}}p_{p}\sqrt{\left[\frac{1}{T}\left(r_{\mathrm{p}}^{1.4286} - r_{\mathrm{p}}^{1.7143}\right)\cdot\left(\frac{1}{1 - r_{\mathrm{D}}^{4}r_{\mathrm{p}}^{1.4286}}\right)\right]}\qquad\text{(54)}
A0 is 0.006111 0.005692 in SI units of ( m3min ) ( K 12kPa ) ( 1mm2 )
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Equation (57) and the equation references in para. 8.6.1.

Equation (57) is now multiplied by 1/1000. Paragraph 8.6.1. now refers to equation 58 instead of equation 57. The correction to both the measured and the background concentration now applies in equations 58 and 62, not in equation 57.

\\displaystyle u_{\mathrm{gas}} = \frac{M_{\mathrm{gas}}}{M_{\mathrm{d}} \times \left(1 - \frac{1}{D}\right) + M_{\mathrm{e}} \times \left(\frac{1}{D}\right)}\)} \times \frac{1}{1000}\qquad\text{(57)}
Depending on the measurement system and calculation method used, the uncorrected emissions results shall be calculated with equations 36, 37, 56, 57 58 or 62, respectively. For calculation of the corrected emissions, cgas in equations 36, 37, 56, 57 58 or 62, respectively, shall be replaced with ccor of equation 66. If instantaneous concentration values cgas,i are used in the respective equation, the corrected value shall also be applied as instantaneous value ccor,i. In equation 57equations 58 and 62, the correction shall be applied to both the measured and the background concentration.

Humidity: saturation vapour pressure and linearity of the humidity measurement device (paras. 8.2. and 9.2.)

Paragraph 8.2. adds that all humidity calculations using generally accepted equations need the saturation vapour pressure. To calculate it, the equation D.15 in Annex D to ISO Standard 8178-4:2020 should be used. Table 7 adds a row with linearity requirements for the humidity measurement device.

For all humidity calculations (for example Ha, Hd) using generally accepted equations the saturation vapour pressure is required. For calculating the saturation vapour pressure which is in general a function of the temperature (at the humidity measurement point) the equation D.15 specified in Annex D to ISO Standard 8178-4:2020 should be used.
Humidity measurement device ≤ 2 % max. 0.98 – 1.02 ≤ 2 % ≥ 0.95

FID burner fuel with helium or nitrogen (para. 9.3.3.1.)

The name of the FID burner fuel is now “Hydrogen mixture” instead of “Hydrogen-helium mixture”. It contains 40 ± 1 per cent hydrogen, and the balance is helium or alternatively nitrogen. Before this supplement, the balance was helium. The heading of paragraph 9.3.3.1. is now “Pure gas” instead of “Pure gases”.

Hydrogen-helium Hydrogen mixture (FID burner fuel)
(40 ± 1 per cent hydrogen, balance helium or alternatively nitrogen)
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NOx analyzer calibration and the NOx mode check (paras. 9.3.6.2. and 9.3.6.8.)

For the calibration, the NOx analyzer must be in the NO mode with the ozonator deactivated. Before this supplement, this sentence did not refer to the ozonator. For the NOx mode check, the analyzer now keeps the NOx mode with the ozonator deactivated. Before, the text said “Switched to NO mode”. The heading of paragraph 9.3.6.8. is now “NOx mode” instead of “NO mode”.

The CLD and the HCLD shall be calibrated in the most common operating range following the manufacturer's specifications using zero and span gas (the NO content of which shall amount to about 80 per cent of the operating range and the NO2 concentration of the gas mixture to less than 5 per cent of the NO concentration). The With the ozonator deactivated, the NOx analyzer shall be in the NO mode so that the span gas does not pass through the converter. The indicated concentration has to be recorded.
Switched to NO Keeping NOx mode with the ozonator deactivated, the flow of oxygen or synthetic air shall be shut off. The NOx reading of the analyzer shall not deviate by more than ±5 per cent from the value measured according to paragraph 9.3.6.2. (the analyzer is in the NO NOx mode).
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Component labels and Figure 12 (Annex 4, Appendix 2)

In the components of Figures 9 and 10, the raw exhaust gas sampling probe is now “SP1” instead of “SP”. In the description of the particulate sampling system, the sample flow controller is now “FC2” instead of “FC3”. Figure 12 has a new drawing.

SP SP1 Raw exhaust gas sampling probe (Figure 9 only)
For a partial flow dilution system, a sample of the diluted exhaust gas is taken from the dilution tunnel DT through the particulate sampling probe PSP and the particulate transfer tube PTT by means of the sampling pump P, as shown in Figure 16. The sample is passed through the filter holder(s) FH that contain the particulate sampling filters. The sample flow rate is controlled by the flow controller FC3FC2.
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Q2Why it changed

Proposed by
Expert from the International Organization of Motor Vehicle Manufacturers (OICA)
Working party
GRPE, 83rd session (June 2021)

Reasons

  • In equations (36) and (37), all calculations after the sum sign must be done inside the sum. Equation (57) must be multiplied by 1/1000 to adjust the number of digits. In paragraph 8.6.1., the equation reference was incorrect, and it must be equation (58).

    Sources (3)
    “In equations (36) and (37), all the calculation equations after Sigma need to be performed in Sigma.”
    “Equation (57) needs to be multiplied by 1/1000 to adjust the number of digits.”
    “In the text, the equation to be referenced is incorrect. It is equation (58) that needs to be referenced.”

  • In the volume flow equation, the coefficient A0 must be divided by 60. A0 must be 0.005692 in the standard conditions (273 K, 101.3 kPa). The discharge coefficient of the SSV must be correlated with the SSV mass flow rate formula. The Reynolds number must be multiplied by 60, and A1 must be 27.43831. The throat diameter dV must be in mm.

    Sources (4)
    “In the dimension of the volume flow equation, the coefficient A0 must be divided by 60. Similarly, the coefficient A0 must be 0.005692 in the standard conditions (273K, 101.3kPa).”
    “The discharge coefficient of the SSV needs to be correlated with the SSV mass flow rate calculation formula. Therefore, the coefficient A0 divided by 60 is added.”
    “Reynolds number must be multiplied by 60. The coefficient A1 must be 27.43831 in the standard state (273K, 101.3kPa).”
    “In addition, the unit of the SSV throat diameter dV must be (mm).”

  • In Figure 9, the raw exhaust gas sampling probe is “SP1”, but the text said “SP”. In Figures 16 and 17, the sample flow controller is “FC2”, but the text said “FC3”. In the text, the flow controller is “FC1”, but Figure 12 showed “FC2”.

    Sources (3)
    “In Figure 9, raw exhaust gas sampling probe is represented by “SP1”, whereas “SP” is indicated in the text.”
    “In Figure 16 and Figure 17, the sample flow controller is represented as “FC2”, whereas in the text, it is “FC3”.”
    “In the text, the flow controller is represented by “FC1”, whereas in Figure 12, it is “FC2”.”

  • UN Regulation No. 49 had no linearity requirements for humidity sensors. The humidity content of the intake air is an essential measure for the calculation of the specific exhaust emission.

    Source
    “UN Regulation No.49 defines no linearity requirements for humidity sensors. As the humidity content of the intake air is an essential measure for the calculation of the specific exhaust emission, it is important to add requirement for humidity sensor.”

  • The representative from OICA explained that helium is now difficult and expensive to acquire. This was the main reason for the request for an alternative option to measure hydrocarbons.

    Source
    “The representative from OICA further explained that helium is now difficult and expensive to acquire as the main reason to request for an alternative option to measure hydrocarbons.”

Document trail

  1. 2021-03ProposalECE/TRANS/WP.29/GRPE/2021/14Proposal by the expert from OICA
  2. —Working party adoptsECE/TRANS/WP.29/GRPE/83Session report, paras. 19 and 22, and Annex X
  3. 2021-09Sent to WP.29ECE/TRANS/WP.29/2021/130Text that GRPE sent to WP.29 and AC.1
  4. 2021-11WP.29 adoptsECE/TRANS/WP.29/1161Adopted at the 185th session (session report, para. 121)
  5. 2022-06-22In forceC.N.210.2022.TREATIES-XI.B.16.49UN depositary notification

Q3Who is affected

Vehicle manufacturer

  • Update your mass emission calculations to the amended equations (36), (37) and (57).
  • Check that your SSV flow calculation uses A0/60, with A0 = 0.005692 and dV in mm.
  • Check that the linearity of your humidity measurement device meets the new requirements.
  • Consider nitrogen as an alternative to helium for the balance of the FID burner fuel (40 ± 1 per cent hydrogen).

Component supplier

  • If you supply test software, update equations (89) and (90) and the value A1 = 27.43831.
  • Update your NOx analyzer instructions: for the NOx mode check, the analyzer keeps the NOx mode with the ozonator deactivated.

Technical service / Approval authority

  • Be ready for test results that use the amended SSV equations and the new values of A0 and A1.
  • Make sure that the humidity measurement device meets the new linearity requirements.
  • Make sure that the NOx mode check keeps the analyzer in the NOx mode with the ozonator deactivated.

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ⓘ This report gives advice only. It is not legal or type-approval advice.

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