(a) THC determination and initial THC/CH4 contamination 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:

xTHC[THC-FID]cor = xTHC[THC-FID]uncor − xTHC[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 an NMC, calculate xNMHC using the NMC's penetration fractions, response factors, and/or combined penetration fractions and response factors as described in § 1065.365, the THC FID's CH4 response factor, RFCH4[THC-FID], from § 1065.360, the initial THC contamination and dry-to-wet corrected THC concentration, xTHC[THC-FID]cor, as determined in paragraph (a) of this section, and the dry-to-wet corrected CH4 concentration, xTHC[NMC-FID]cor, optionally corrected for initial THC contamination as determined in paragraph (a) of this section.

(i) Use the following equation for an NMC configured as described in § 1065.365(d):

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] = NMC combined C2H6 response factor and penetration fraction, according to § 1065.365(d). RFPFCH4[NMC-FID] = NMC combined CH4 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 RFPFCH4[NMC-FID] = 1.000 RFCH4[THC-FID] = 1.05

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

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] = NMC 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] = NMC C2H6 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

(iii) Use the following equation for an NMC configured as described in § 1065.365(f):

Eq. 1065.660-4 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] = NMC 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] = NMC combined C2H6 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

(3) For a GC-FID or FTIR, calculate xNMHC using the THC analyzer's CH4 response factor, RFCH4[THC-FID], from § 1065.360, and the initial THC contamination and dry-to-wet corrected THC concentration, xTHC[THC-FID]cor, as determined in paragraph (a) of this section as follows:

χNMHC = χTHC[THC-FID]cor − RFCH4[THC-FID] · χCH4 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 xNMHC by summing the hydrocarbon species listed in § 1065.266(c) as follows:

Eq. 1065.660-6 Where: xNMHC = concentration of NMHC. 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:

xC2H6 = 4.9 µmol/mol 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 xCH2O2 = 0.1 µmol/mol xCH4O = 0.1 µmol/mol xNMHC = 4.9 + 0.9 + 0.8 + 0.4 + 0.5 + 0.3 + 0.8 + 0.3 + 0.1 + 0.1 xNMHC = 9.1 µmol/mol

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

(1) Calculate xNMNEHC 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 C2H6, 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 xNMNEHC using the THC analyzer's CH4 response factor, RFCH4[THC-FID], and C2H6 response factor, RFC2H6[THC-FID], from § 1065.360, the initial contamination and dry-to-wet corrected THC concentration, xTHC[THC-FID]cor, as determined in paragraph (a) of this section, the dry-to-wet corrected CH4 concentration, xCH4, as determined in paragraph (d) of this section, and the dry-to-wet corrected C2H6 concentration, xC2H6, as determined in paragraph (e) of this section as follows:

xNMNEHC = xTHC[THC-FID}cor − RFCH4{THC-FID}. xCH4 − RFC2H6{THC-FID] . xC2H6 Eq. 1065.660-7 Where: xNMNEHC = concentration of NMNEHC. 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, NMC FID, or FTIR. RFC2H6[THC-FID] = response factor of THC-FID to C2H6. xC2H6 = the C1-equivalent concentration of C2H6, 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 RFC2H6[THC-FID] = 1.02 xC2H6 = 10.6 µmol/mol xNMNEHC = 145.6 − 0.970 · 18.9 − 1.02 · 10.6 xNMNEHC = 116.5 µmol/mol

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

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 xCH2O2 = 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 (CH4) concentration, xCH4:

(1) For an NMC, calculate xCH4 using the NMC's penetration fractions, response factors, and/or combined penetration fractions and response factors as described in § 1065.365, the THC FID's CH4 response factor, RFCH4[THC-FID], from § 1065.360, the initial THC contamination and dry-to-wet corrected THC concentration, xTHC[THC-FID]cor, as determined in paragraph (a) of this section, and the dry-to-wet corrected CH4 concentration, xTHC[NMC-FID]cor, optionally corrected for initial THC contamination as determined in paragraph (a) of this section.

(i) Use the following equation for an NMC configured as described in § 1065.365(d):

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] = NMC combined C2H6 response factor and penetration fraction, according to § 1065.365(d). RFCH4[THC-FID] = response factor of THC FID to CH4, according to § 1065.360(d). RFPFCH4[NMC-FID] = NMC combined CH4 response factor and penetration fraction, according to § 1065.365(d).

Example:

xTHC[NMC-FID]cor = 10.4 µmol/mol xTHC[THC-FID]cor = 150.3 µmol/mol RFPFC2H6[NMC-FID] = 0.019 RFPFCH4[NMC-FID] = 1.000 RFCH4[THC-FID] = 1.05

(ii) Use the following equation for an NMC configured as described in § 1065.365(e):

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] = NMC C2H6 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] = NMC 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

(iii) Use the following equation for an NMC configured as described in § 1065.365(f):

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 C2H6 response factor and penetration fraction of the NMC, according to § 1065.365(f). PFCH4[NMC-FID] = NMC 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

(2) For a GC-FID or FTIR, xCH4 is the actual dry-to-wet corrected CH4 concentration as measured by the analyzer.

(e) C2H6 determination. For a GC-FID or FTIR, xC2H6 is the C1-equivalent, dry-to-wet corrected C2H6 concentration as measured by the analyzer.

[89 FR 29819, Apr. 22, 2024]