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

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

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

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

x THC [ THC FID ] cor = x THC [ THC FID ] uncor x THC [ THC FID ] init Eq. 1065.660-1

Example:
xTHCuncor = 150.3 µmol/mol
xTHCinit = 1.1 µmol/mol
xTHCcor = 150.3 - 1.1
xTHCcor = 149.2 µmol/mol

(2) For the NMHC determination described in paragraph (b) of this section, correct xTHC[THC-FID] for initial THC contamination using Eq. 1065.660-1. You may correct xTHC[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 xTHC[THC-FID] for initial THC contamination using Eq. 1065.660-1. You may correct xTHC[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 xTHC[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, xNMHC:

(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 cutters, calculate χNMHC using the nonmethane cutter's methane penetration fraction, PFCH4[NMC-FID], and the ethane response factor penetration fraction, RFPFC2H6[NMC-FID], from § 1065.365, the THC FID's methane response factor, RFCH4[THC-FID], from § 1065.360, the initial THC contamination and dry-to-wet corrected THC concentration, χTHC[THC-FID]cor, as determined in paragraph (a) of this section, and the dry-to-wet corrected methane concentration, χTHC[NMC-FID]cor, optionally corrected for initial THC contamination as determined in paragraph (a) of this section.

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

x NMHC = x THC [ THC-FID ] cor x THC [ NMC-FID ] cor · RF CH $ [ THC-FID ] 1 RFPF C 2 H 6 [ NMC-FID ] · RF CH 4 [ THC-FID ] Eq. 1065.660-2

Where:
xNMHC = concentration of NMHC.
xTHC[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.
xTHC[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.
RFCH4[THC-FID] = response factor of THC FID to CH4, according to § 1065.360(d).
RFPFC2H6[NMC-FID] = nonmethane cutter combined ethane response factor and penetration fraction, according to § 1065.365(d).
Example:
xTHC[THC-FID]cor = 150.3 µmol/mol
xTHC[NMC-FID]cor = 20.5 µmol/mol
RFPFC2H6[NMC-FID] = 0.019
RFCH4[THC-FID] = 1.05

x NMHC 150.3 20.5 · 1.05 1 0.019 · 1.05

xNMHC = 131.4 µmol/mol

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

x NMHC = x THC [ THC-FID ] cor · PF CH 4 [ NMC-FID ] x THC [ NMC-FID ] cor PF CH 4 [ NMC-FID ] PF C 2 H 6 [ NMC-FID ] Eq. 1065.660-3

Where:
xNMHC = concentration of NMHC.
xTHC[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.
PFCH4[NMC-FID] = nonmethane cutter CH4 penetration fraction, according to § 1065.365(e).
xTHC[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.
PFC2H6[NMC-FID] = nonmethane cutter ethane penetration fraction, according to § 1065.365(e).
Example:
xTHC[THC-FID]cor = 150.3 µmol/mol
PFCH4[NMC-FID] = 0.990
xTHC[NMC-FID]cor = 20.5 µmol/mol
PFC2H6[NMC-FID] = 0.020

x NMHC 150.3 0.990 20.5 0.990 0.020

xNMHC = 132.3 µmol/mol

(iii) Use the following equation for penetration fractions determined using an NMC configuration as outlined 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):

x NMHC = x THC [ THC-FID ] cor · PF CH 4 [ NMC-FID ] x THC [ NMC-FID ] cor · RF CH 4 [ THC-FID ] PF CH 4 [ NMC-FID ] RFPF C 2 H 6 [ NMC-FID ] · RF CH 4 [ THC-FID ] Eq. 1065.660-3

Where:
xNMHC = concentration of NMHC.
xTHC[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.
PFCH4[NMC-FID] = nonmethane cutter CH4 penetration fraction, according to § 1065.365(f).
xTHC[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.
RFPFC2H6[NMC-FID] = nonmethane cutter CH4 combined ethane response factor and penetration fraction, according to § 1065.365(f).
RFCH4[THC-FID] = response factor of THC FID to CH4, according to § 1065.360(d).
Example:
xTHC[THC-FID]cor = 150.3 µmol/mol
PFCH4[NMC-FID] = 0.990
xTHC[NMC-FID]cor = 20.5 µmol/mol
RFPFC2H6[NMC-FID] = 0.019
RFCH4[THC-FID] = 0.980

x NMHC = 150.3 · 0.990 20.5 · 0.980 0.990 0.019 · 0.980

xNMHC = 132.5 µmol/mol

(3) For a GC-FID or FTIR, calculate χNMHC using the THC analyzer's methane response factor, RFCH4[THC-FID], from § 1065.360, and the initial THC contamination and dry-to-wet corrected THC concentration, χTHC[THC-FID]cor, as determined in paragraph (a) of this section as follows:

x NMHC = x THC [ THC-FID ] cor RF CH 4 [ THC-FID ] · x CH 4 Eq. 1065.660-5

Where:
xNMHC = concentration of NMHC.
xTHC[THC-FID]cor = concentration of THC, initial THC contamination and dry-to-wet corrected, as measured by the THC FID.
RFCH4[THC-FID] = response factor of THC-FID to CH4.
xCH4 = concentration of CH4, dry-to-wet corrected, as measured by the GC-FID or FTIR.
Example:
xTHC[THC-FID]cor = 145.6 µmol/mol
RFCH4[THC-FID] = 0.970
xCH4 = 18.9 µmol/mol
xNMHC = 145.6−0.970 · 18.9
xNMHC = 127.3 µmol/mol

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

Where:
χNMHC = concentration of NMHC.
χHCi = the C1-equivalent concentration of hydrocarbon species i as measured by the FTIR, not corrected for initial contamination.
χHCi-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:
χC2H6 = 4.9 µmol/mol
χC2H4 = 0.9 µmol/mol
χC2H2 = 0.8 µmol/mol
χC3H8 = 0.4 µmol/mol
χC3H6 = 0.5 µmol/mol
χC4H10 = 0.3 µmol/mol
χCH2O = 0.8 µmol/mol
χC2H4O = 0.3 µmol/mol
χCH2O2 = 0.1 µmol/mol
χCH4O = 0.1 µmol/mol
χNMHC = 4.9 + 0.9 + 0.8 + 0.4 + 0.5 + 0.3 + 0.8 + 0.3 + 0.1 + 0.1
χNMHC = 9.1 µmol/mol

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

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

(2) For a GC-FID, NMC FID, or FTIR, calculate χNMNEHC using the THC analyzer's methane response factor, RFCH4[THC-FID], and ethane response factor, RFC2H6[THC-FID], from § 1065.360, the initial contamination and dry-to-wet corrected THC concentration, χTHC[THC-FID]cor, as determined in paragraph (a) of this section, the dry-to-wet corrected methane concentration, χCH4, as determined in paragraph (d) of this section, and the dry-to-wet corrected ethane concentration, χC2H6, as determined in paragraph (e) of this section as follows:

Where:
χNMNEHC = concentration of NMNEHC.
χTHC[THC-FID]cor = concentration of THC, initial THC contamination and dry-to-wet corrected, as measured by the THC FID.
RFCH4[THC-FID] = response factor of THC-FID to CH4.
χCH4 = concentration of CH4, dry-to-wet corrected, as measured by the GC-FID, NMC FID, or FTIR.
RFC2H6[THC-FID] = response factor of THC-FID to C2H6.
χC2H6 = the C1-equivalent concentration of C2H6, dry-to-wet corrected, as measured by the GC-FID or FTIR.
Example:
χTHC[THC-FID]cor = 145.6 µmol/mol
RFCH4[THC-FID] = 0.970
χCH4 = 18.9 µmol/mol
RFC2H6[THC-FID] = 1.02
χC2H6 = 10.6 µmol/mol
χNMNEHC = 145.6−0.970 · 18.9−1.02 · 10.6
χNMNEHC = 116.5 µmol/mol

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

x NMNEHC = i = 1 N ( x HCi x HCi−init ) Eq. 1065.660-8

Where:
xNMNEHC = concentration of NMNEHC.
xHCi = the C1-equivalent concentration of hydrocarbon species i as measured by the FTIR, not corrected for initial contamination.
xHCi-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:
xC2H4 = 0.9 µmol/mol
xC2H2 = 0.8 µmol/mol
xC3H8 = 0.4 µmol/mol
xC3H6 = 0.5 µmol/mol
xC4H10 = 0.3 µmol/mol
xCH2O = 0.8 µmol/mol
xC2H4O = 0.3 µmol/mol
xC2H2O2 = 0.1 µmol/mol
xCH4O = 0.1 µmol/mol
xNMNEHC = 0.9 + 0.8 + 0.4 + 0.5 + 0.3 + 0.8 + 0.3 + 0.1 + 0.1
xNMNEHC = 4.2 µmol/mol

(d) CH4 determination. Use one of the following methods to determine methane concentration, χCH4:

(1) For nonmethane cutters, calculate χCH4 using the nonmethane cutter's methane penetration fraction, PFCH4[NMC-FID], and the ethane response factor penetration fraction, RFPFC2H6[NMC-FID, from § 1065.365, the THC FID's methane response factor, RFCH4[THC-FID], from § 1065.360, the initial THC contamination and dry-to-wet corrected THC concentration, χTHC[THC-FID]cor, as determined in paragraph (a) of this section, and the dry-to-wet corrected methane concentration, χTHC[NMC-FID]cor, optionally corrected for initial THC contamination as determined in paragraph (a) of this section.

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

x CH 4 = x THC [NMC-FID]cor x THC [THC-FID]cor × RFPF C 2 H 6 [NMC-FID] 1 RFPF C2H6 [NMC-FID] × RF CH 4 [THC-FID] Eq. 1065.660-9

Where:
xCH4 = concentration of CH4.
xTHC[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.
xTHC[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.
RFPFC2H6[NMC-FID] = the combined ethane response factor and penetration fraction of the nonmethane cutter, according to § 1065.365(d).
RFCH4[THC-FID] = response factor of THC FID to CH4, according to § 1065.360(d).
Example:
xTHC[NMC-FID]cor = 10.4 µmol/mol
xTHC[THC-FID]cor = 150.3 µmol/mol
RFPFC2H6[NMC-FID] = 0.019
RFCH4[THC-FID] = 1.05

x CH 4 = 10.4 150.3 · 0.019 1 0.019 · 1.05

xCH4 = 7.69 µmol/mol

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

x CH 4 = x THC [NMC-FID]cor x THC [THC-FID]cor · PF C 2 H 6 [NMC-FID] RF CH 4 [THC-FID] · ( PF CH 4 [NMC-FID] PF C 2 H 6 [NMC-FID] ) Eq. 1065.660-10

Where:
xCH4 = concentration of CH4.
xTHC[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.
xTHC[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.
PFC2H6[NMC-FID] = nonmethane cutter ethane penetration fraction, according to § 1065.365(e).
RFCH4[THC-FID] = response factor of THC FID to CH4, according to § 1065.360(d).
PFCH4[NMC-FID] = nonmethane cutter CH4 penetration fraction, according to § 1065.365(e).
Example:
xTHC[NMC-FID]cor = 10.4 µmol/mol
xTHC[THC-FID]cor = 150.3 µmol/mol
PFC2H6[NMC-FID] = 0.020
RFCH4[THC-FID] = 1.05
PFCH4[NMC-FID] = 0.990

x CH 4 = 10.4 150.3 · 0.020 1.05 · ( 0.990 · 0.020 )

xCH4 = 7.25 µmol/mol

(iii) Use the following equation for penetration fractions determined using an NMC configuration as outlined 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):

x CH 4 = x THC [NMC-FID]cor x THC [THC-FID]cor · RFPF C 2 H 6 [NMC-FID] PF CH 4 [NMC-FID] RFPF C 2 H 6 [NMC-FID] · RF CH 4 [THC-FID] Eq. 1065.660-11

Where:
xCH4 = concentration of CH4.
xTHC[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.
xTHC[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.
RFPFC2H6[NMC-FID] = the combined ethane response factor and penetration fraction of the nonmethane cutter, according to § 1065.365(f).
PFCH4[NMC-FID] = nonmethane cutter CH4 penetration fraction, according to § 1065.365(f).
RFCH4[THC-FID] = response factor of THC FID to CH4, according to § 1065.360(d).
Example:
xTHC[NMC-FID]cor = 10.4 µmol/mol
xTHC[THC-FID]cor = 150.3 µmol/mol
RFPFC2H6[NMC-FID] = 0.019
PFCH4[NMC-FID] = 0.990
RFCH4[THC-FID] = 1.05

x CH 4 = 10.4 150.3 · 0.019 0.990 0.019 · 1.05

xCH4 = 7.78 µmol/mol

(2) For a GC-FID or FTIR, χCH4 is the actual dry-to-wet corrected methane concentration as measured by the analyzer.

(e) C2H6determination. For a GC-FID or FTIR, χC2H6 is the C1-equivalent, dry-to-wet corrected ethane concentration as measured by the analyzer.

[76 FR 57462, Sept. 15, 2011, as amended at 81 FR 74184, Oct. 25, 2016; 86 FR 34566, June 29, 2021]

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