§ 1065.660 - THC, NMHC, NMNEHC, CH4, and C2H6 determination.

§ 1065.660 THC, NMHC, NMNEHC, CH₄, and C₂H₆ determination.

Cross Reference

Link to an amendment published at 89 FR 29819, Apr. 22, 2024.

(a) THC determination and initial THC/CH₄contamination corrections.

(1) If we require you to determine THC emissions, calculate ^x_{THC[THC-FID]cor} using the initial THC contamination concentration ^x_{THC[THC-FID]init} from § 1065.520 as follows:

Example:

x

^x_{THC[THC-FID]cor} = ^x_{THC[THC-FID]uncor} − ^x_{THC[THC-FID]init}

Eq. 1065.660-1

Example:

χ_THCuncor = 150.3 µmol/mol

x

χ_THCinit = 1.1 µmol/mol

x

χ_THCcor = 150.3—1.1

x

χ_THCcor = 149.2 µmol/mol

(2) For the NMHC determination described in paragraph (b) of this section, correct x χ_THC[THC-FID] for initial THC contamination using Eq. 1065.660-1. You may correct x χ_THC[NMC-FID] for initial contamination of the CH₄ sample train using Eq. 1065.660-1, substituting in CH₄ concentrations for THC.

(3) For the NMNEHC determination described in paragraph (c) of this section, correct x χ_THC[THC-FID] for initial THC contamination using Eq. 1065.660-1. You may correct x χ_THC[NMC-FID] for initial contamination of the CH₄ sample train using Eq. 1065.660-1, substituting in CH₄ concentrations for THC.

(4) For the CH₄ determination described in paragraph (d) of this section, you may correct x χ_THC[NMC-FID] for initial THC contamination of the CH₄ sample train using Eq. 1065.660-1, substituting in CH₄ concentrations for THC.

(5) You may calculate THC as the sum of NMHC and CH₄ if you determine CH₄ with an FTIR as described in paragraph (d)(2) of this section and NMHC with an FTIR using the additive method from paragraph (b)(4) of this section.

(6) You may calculate THC as the sum of NMNEHC, C₂H₆, and CH₄ if you determine CH₄ with an FTIR as described in paragraph (d)(2) of this section, C₂H₆ with an FTIR as described in paragraph (e) of this section, and NMNEHC with an FTIR using the additive method from paragraph (c)(3) of this section.

(b) NMHC determination. Use one of the following to determine NMHC concentration, x χ_NMHC:

(1) If you do not measure CH₄, you may omit the calculation of NMHC concentrations and calculate the mass of NMHC as described in § 1065.650(c)(5).

(2) For nonmethane cuttersan NMC, calculate χ_NMHC using the nonmethane cutterNMC's methane penetration fraction, PF_CH4[NMC-FID], and the ethane response factor penetration fraction, RFPF_{C2H6[NMC-FID]}, from fractions, response factors, and/or combined penetration fractions and response factors as described in § 1065.365, the THC FID's methane CH₄ response factor, RF_{CH4[THC-FID],} from § 1065.360, the initial THC contamination and dry-to-wet corrected THC concentration, χ_{THC[THC-FID]cor,} as determined in paragraph (a) of this section, and the dry-to-wet corrected methane CH₄ concentration, χ_{THC[NMC-FID]cor,} optionally corrected for initial THC contamination as determined in paragraph (a) of this section.

(i) If you need to account for penetration fractions determined as a function of molar water concentration, use Eq. 1065.660-4. Otherwise, use Use the following equation for penetration fractions determined using an NMC configuration configured as outlined described in § 1065.365(d):

Eq. 1065.660-2

Where:

xχ_NMHC = concentration of NMHC.

xχ_{THC[THC-FID]cor} = concentration of THC, initial THC contamination and dry-to-wet corrected, as measured by the THC FID during sampling while bypassing the NMC.

xχ_{THC[NMC-FID]cor} = concentration of THC, initial THC contamination (optional) and dry-to-wet corrected, as measured by the NMC FID during sampling through the NMC.

RF_CH4[THC-FID] = response factor of THC FID to CH_4, according to § 1065.360(d).

RFPF_{C2H6[NMC-FID]} = nonmethane cutter combined ethane NMC combined C₂H₆ response factor and penetration fraction, according to § 1065.365(d).

RFPF_CH4[NMC-FID] = NMC combined CH₄ response factor and penetration fraction, according to § 1065.365(d).

Example:

x

χ_{THC[THC-FID]cor} = 150.3 µmol/mol

x

χ_{THC[NMC-FID]cor} = 20.5 µmol/mol

RFPF_{C2H6[NMC-FID]} = 0.019

RFPF_CH4[NMC-FID] = 1.000

RF_CH4[THC-FID] = 1.05

x_NMHC = 131.4 µmol/mol

(ii) Use the following equation for penetration fractions determined using an NMC configuration as outlined in § 1065.365(e):

Eq. 1065.660-3

Where:

xχ_NMHC = concentration of NMHC.

xχ_{THC[THC-FID]cor} = concentration of THC, initial THC contamination and dry-to-wet corrected, as measured by the THC FID during sampling while bypassing the NMC.

PF_CH4[NMC-FID] = nonmethane cutter NMC CH₄ penetration fraction, according to § 1065.365(e).

xχ_{THC[NMC-FID]cor} = concentration of THC, initial THC contamination (optional) and dry-to-wet corrected, as measured by the THC FID during sampling through the NMC.

PF_{C2H6[NMC-FID]} = nonmethane cutter ethane NMC C₂H₆ penetration fraction, according to § 1065.365(e).

Example:

x

χ_{THC[THC-FID]cor} = 150.3 µmol/mol

PF_CH4[NMC-FID] = 0.990

x

χ_{THC[NMC-FID]cor} = 20.5 µmol/mol

PF_{C2H6[NMC-FID]} = 0.020

x_NMHC = 132.3 µmol/mol

(iii) Use the following equation for penetration fractions determined using an NMC configuration configured as outlined described in § 1065.365(f) or for penetration fractions determined as a function of molar water concentration using an NMC configuration as outlined in § 1065.365(d):

Where:

x

:

Eq. 1065.660-4

Where:

χ_NMHC = concentration of NMHC.

xχ_{THC[THC-FID]cor} = concentration of THC, initial THC contamination and dry-to-wet corrected, as measured by the THC FID during sampling while bypassing the NMC.

PF_CH4[NMC-FID] = nonmethane cutter NMC CH₄ penetration fraction, according to § 1065.365(f).

xχ_{THC[NMC-FID]cor} = concentration of THC, initial THC contamination (optional) and dry-to-wet corrected, as measured by the THC FID during sampling through the NMC.

RFPF_{C2H6[NMC-FID]} = nonmethane cutter CH₄ combined ethane NMC combined C₂H₆ response factor and penetration fraction, according to § 1065.365(f).

RF_CH4[THC-FID] = response factor of THC FID to CH_4, according to § 1065.360(d).

Example:

x

χ_{THC[THC-FID]cor} = 150.3 µmol/mol

PF_CH4[NMC-FID] = 0.990

x

χ_{THC[NMC-FID]cor} = 20.5 µmol/mol

RFPF_{C2H6[NMC-FID]} = 0.019

RF_CH4[THC-FID] = 0.980

x_NMHC = 132.5 µmol/mol

(3) For a GC-FID or FTIR, calculate χ_NMHC using the THC analyzer's methane CH₄ response factor, RF_{CH4[THC-FID],} from § 1065.360, and the initial THC contamination and dry-to-wet corrected THC concentration, χ_{THC[THC-FID]cor,} as determined in paragraph (a) of this section as follows:

Where:

x

χ_NMHC = χ_{THC[THC-FID]cor} − RF_CH4[THC-FID] · χ_CH4

Eq. 1065.660-5

Where:

χ_NMHC = concentration of NMHC.

xχ_{THC[THC-FID]cor} = concentration of THC, initial THC contamination and dry-to-wet corrected, as measured by the THC FID.

RF_CH4[THC-FID] = response factor of THC-FID to CH_4.

xχ_CH4 = concentration of CH_4, dry-to-wet corrected, as measured by the GC-FID or FTIR.

Example:

x

χ_{THC[THC-FID]cor} = 145.6 µmol/mol

RF_CH4[THC-FID] = 0.970

x

χ_CH4 = 18.9 µmol/mol

x

χ_NMHC = 145.

6−0

6—0.970 · 18.9

x

χ_NMHC = 127.3 µmol/mol

(4) For an FTIR, calculate χ_NMHC by summing the hydrocarbon species listed in § 1065.266(c) as follows:

Eq. 1065.660-6

Where:

χ_NMHC = concentration of NMHC.

χ_HCi = the C₁-equivalent concentration of hydrocarbon species i as measured by the FTIR, not corrected for initial contamination.

χ_HCi-init = the C₁-equivalent concentration of the initial system contamination (optional) of hydrocarbon species i, dry-to-wet corrected, as measured by the FTIR.

Example:

χ_C2H6 = 4.9 µmol/mol

χ_C2H4 = 0.9 µmol/mol

χ_C2H2 = 0.8 µmol/mol

χ_C3H8 = 0.4 µmol/mol

χ_C3H6 = 0.5 µmol/mol

χ_C4H10 = 0.3 µmol/mol

χ_CH2O = 0.8 µmol/mol

χ_C2H4O = 0.3 µmol/mol

χ_CH2O2 = 0.1 µmol/mol

χ_CH4O = 0.1 µmol/mol

χ_NMHC = 4.9 + 0.9 + 0.8 + 0.4 + 0.5 + 0.3 + 0.8 + 0.3 + 0.1 + 0.1

χ

_NMHC

_NMHC = 9.1 µmol/mol

(c) NMNEHC determination. Use one of the following methods to determine NMNEHC concentration, x χ_NMNEHC:

(1) Calculate x χ_NMNEHC based on the test fuel's ethane content as follows:

(i) If the content of your test fuel contains less than 0.010 mol/mol of ethane, you may omit the calculation of NMNEHC concentration and calculate the mass of NMNEHC as described in § 1065.650(c)(6)(i).

(ii) If the content of your fuel test contains at least 0.010 mol/mol of ethaneC₂H₆, you may omit the calculation of NMNEHC concentration and calculate the mass of NMNEHC as described in § 1065.650(c)(6)(ii).

(2) For a GC-FID, NMC FID, or FTIR, calculate χ_NMNEHC using the THC analyzer's methane CH₄ response factor, RF_{CH4[THC-FID],} and ethane C₂H₆ response factor, RF_{C2H6[THC-FID],} from § 1065.360, the initial contamination and dry-to-wet corrected THC concentration, χ_{THC[THC-FID]cor,} as determined in paragraph (a) of this section, the dry-to-wet corrected methane CH₄ concentration, χ_CH4, as determined in paragraph (d) of this section, and the dry-to-wet corrected ethane C₂H₆ concentration, χ_C2H6, as determined in paragraph (e) of this section as follows:

χ_NMNEHC = χ_{THC[THC-FID}cor} − RF_CH4{THC-FID}. χ_CH4 − RF_{C2H6{THC-FID]} . χ_C2H6

Eq. 1065.660-7

Where:

χ_NMNEHC = concentration of NMNEHC.

χ_{THC[THC-FID]cor} = concentration of THC, initial THC contamination and dry-to-wet corrected, as measured by the THC FID.

RF_CH4[THC-FID] = response factor of THC-FID to CH_4.

χ_CH4 = concentration of CH_4, dry-to-wet corrected, as measured by the GC-FID, NMC FID, or FTIR.

RF_{C2H6[THC-FID]} = response factor of THC-FID to C₂H_6.

χ_C2H6 = the C₁-equivalent concentration of C₂H_6, dry-to-wet corrected, as measured by the GC-FID or FTIR.

Example:

χ_{THC[THC-FID]cor} = 145.6 µmol/mol

RF_CH4[THC-FID] = 0.970

χ_CH4 = 18.9 µmol/mol

RF_{C2H6[THC-FID]} = 1.02

χ_C2H6 = 10.6 µmol/mol

χ_NMNEHC = 145.

6−0

6 − 0.970 · 18.

9−1

9 − 1.02 · 10.6

χ_NMNEHC = 116.5 µmol/mol

(3) For an FTIR, calculate x_NMNEHC by summing the hydrocarbon species listed in § 1065.266(c) as follows:

Eq. 1065.660-8

Where:

xχ_NMNEHC = concentration of NMNEHC.

x_HCi χ_HCi = the C₁-equivalent concentration of hydrocarbon species i as measured by the FTIR, not corrected for initial contamination. xHCi

χ_HCi-init = the C₁-equivalent concentration of the initial system contamination (optional) of hydrocarbon species i, dry-to-wet corrected, as measured by the FTIR.

Example:

x

χ_C2H4 = 0.9 µmol/mol

x

χ_C2H2 = 0.8 µmol/mol

x

χ_C3H8 = 0.4 µmol/mol

x

χ_C3H6 = 0.5 µmol/mol

x

χ_C4H10 = 0.3 µmol/mol

x

χ_CH2O = 0.8 µmol/mol

x

χ_C2H4O = 0.3 µmol/mol

x_C2H2O2

χ_CH2O2 = 0.1 µmol/mol

x

χ_CH4O = 0.1 µmol/mol

x

χ_NMNEHC = 0.9 + 0.8 + 0.4 + 0.5 + 0.3 + 0.8 + 0.3 + 0.1 + 0.1

x_NMNEHC = 4.2 µmol/mol

(d) CH₄ determination. Use one of the following methods to determine methane (CH₄) concentration, χ_CH4:

(1) For nonmethane cuttersan NMC, calculate χ x_CH4 using the nonmethane cutterNMC's methane penetration fraction, PF_CH4[NMC-FID], and the ethane response factor penetration fraction, RFPF_C2H6[NMC-FID, from fractions, response factors, and/or combined penetration fractions and response factors as described in § 1065.365, the THC FID's methane CH₄ response factor, RF_{CH4[THC-FID],} from § 1065.360, the initial THC contamination and dry-to-wet corrected THC concentration, χ_{THC[THC-FID]cor,} as determined in paragraph (a) of this section, and the dry-to-wet corrected methane CH₄ concentration, χ_{THC[NMC-FID]cor,} optionally corrected for initial THC contamination as determined in paragraph (a) of this section.

(i) If you need to account for penetration fractions determined as a function of molar water concentration, use Eq. 1065.660-11. Otherwise, use Use the following equation for penetration fractions determined using an NMC configuration configured as outlined described in § 1065.365(d):

Eq. 1065.660-9

Where:

xχ_CH4 = concentration of CH₄.

xχ_{THC[NMC-FID]cor} = concentration of THC, initial THC contamination (optional) and dry-to-wet corrected, as measured by the NMC FID during sampling through the NMC.

xχ_{THC[THC-FID]cor} = concentration of THC, initial THC contamination and dry-to-wet corrected, as measured by the THC FID during sampling while bypassing the NMC.

RFPF_{C2H6[NMC-FID]} = the combined ethane NMC combined C₂H₆ response factor and penetration fraction of the nonmethane cutter, according to § 1065.365(d).

RF_CH4[THC-FID] = response factor of THC FID to CH_4, according to § 1065.360(d).

RFPF_CH4[NMC-FID] = NMC combined CH₄ response factor and penetration fraction, according to § 1065.365(d).

Example:

x

χ_{THC[NMC-FID]cor} = 10.4 µmol/mol

x

χ_{THC[THC-FID]cor} = 150.3 µmol/mol

RFPF_{C2H6[NMC-FID]} = 0.019

RFPF_CH4[NMC-FID] = 1.000

RF_CH4[THC-FID] = 1.05

x_CH4 = 7.69 µmol/mol

(ii) Use the following equation for penetration fractions determined using an NMC configuration configured as outlined described in § 1065.365(e):

Eq. 1065.660-10

Where:

x_CH4 = concentration of CH_4.

xχ_{THC[NMC-FID]cor} = concentration of THC, initial THC contamination (optional) and dry-to-wet corrected, as measured by the NMC FID during sampling through the NMC.

xχ_{THC[THC-FID]cor} = concentration of THC, initial THC contamination and dry-to-wet corrected, as measured by the THC FID during sampling while bypassing the NMC.

PF_{C2H6[NMC-FID]} = nonmethane cutter ethane NMC C₂H₆ penetration fraction, according to § 1065.365(e).

RF_CH4[THC-FID] = response factor of THC FID to CH_4, according to § 1065.360(d).

PF_CH4[NMC-FID] = nonmethane cutter NMC CH₄ penetration fraction, according to § 1065.365(e).

Example:

x

χ_{THC[NMC-FID]cor} = 10.4 µmol/mol

x

χ_{THC[THC-FID]cor} = 150.3 µmol/mol

PF_{C2H6[NMC-FID]} = 0.020

RF_CH4[THC-FID] = 1.05

PF_CH4[NMC-FID] = 0.990

x_CH4 = 7.25 µmol/mol

(iii) Use the following equation for penetration fractions determined using an NMC configuration configured as outlined described in § 1065.365(f) or for penetration fractions determined as a function of molar water concentration using an NMC configuration as outlined in § 1065.365(d):

Where:

x

:

Eq. 1065.660-11

Where:

χ_CH4 = concentration of CH_4.

xχ_{THC[NMC-FID]cor} = concentration of THC, initial THC contamination (optional) and dry-to-wet corrected, as measured by the NMC FID during sampling through the NMC.

xχ_{THC[THC-FID]cor} = concentration of THC, initial THC contamination and dry-to-wet corrected, as measured by the THC FID during sampling while bypassing the NMC.

RFPF_{C2H6[NMC-FID]} = the combined ethane C₂H₆ response factor and penetration fraction of the nonmethane cutterNMC, according to § 1065.365(f).

PF_CH4[NMC-FID] = nonmethane cutter NMC CH₄ penetration fraction, according to § 1065.365(f).

RF_CH4[THC-FID] = response factor of THC FID to CH_4, according to § 1065.360(d).

Example:

x

χ_{THC[NMC-FID]cor} = 10.4 µmol/mol

x

χ_{THC[THC-FID]cor} = 150.3 µmol/mol

RFPF_{C2H6[NMC-FID]} = 0.019

PF_CH4[NMC-FID] = 0.990

RF_CH4[THC-FID] = 1.05

x_CH4 = 7.78 µmol/mol

(2) For a GC-FID or FTIR, χ x_CH4 is the actual dry-to-wet corrected methane CH₄ concentration as measured by the analyzer.

(e) C₂ H₆ determination. For a GC-FID or FTIR, χ_C2H6 is the C₁-equivalent, dry-to-wet corrected ethane C₂H₆ concentration as measured by the analyzer.

[76 89 FR 5746229819, SeptApr. 15, 2011, as amended at 81 FR 74184, Oct. 25, 2016; 86 FR 34566, June 29, 2021; 88 FR 4686, Jan. 24, 202322, 2024]