# Title 40

## SECTION 1065.660

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

§ 1065.660 THC, NMHC, NMNEHC, CH4, and C2H6 determination.(a) *THC determination and initial THC/CH*4
*contamination 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:

*x*THCuncor = 150.3 µmol/mol

*x*THCinit = 1.1 µmol/mol

*x*THCcor = 150.3 - 1.1

*x*THCcor = 149.2 µmol/mol

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

(b) *NMHC determination.* Use one of the following to
determine NMHC concentration, *x*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 cutters, calculate *x*NMHC using the
nonmethane cutter's penetration fraction (*PF*) of CH4 and the
response factor penetration fraction (*RFPF*) of C2H6 from §
1065.365, the response factor (*RF*) of the THC FID to CH4
from § 1065.360, the initial THC contamination and dry-to-wet
corrected THC concentration *x*THC[THC-FID]cor as determined
in paragraph (a) of this section, and the dry-to-wet corrected CH4
concentration *x*THC[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):

Where:*x*NMHC = concentration of NMHC.

*x*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.

*x*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 CH4, according to § 1065.360(d).

*RFPF*C2H6[NMC-FID] = nonmethane cutter combined ethane response factor and penetration fraction, according to § 1065.365(d). Example:

*x*THC[THC-FID]cor = 150.3 µmol/mol

*x*THC[NMC-FID]cor = 20.5 µmol/mol

*RFPF*C2H6[NMC-FID] = 0.019

*RF*CH4[THC-FID] = 1.05

*x*NMHC = 131.4 µmol/mol

(ii) For penetration fractions determined using an NMC configuration as outlined in section § 1065.365(e), use the following equation:

Where:*x*NMHC = concentration of NMHC.

*x*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 CH4 penetration fraction, according to § 1065.365(e).

*x*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 penetration fraction, according to § 1065.365(e). Example:

*x*THC[THC-FID]cor = 150.3 µmol/mol

*PF*CH4[NMC-FID] = 0.990

*x*THC[NMC-FID]cor = 20.5 µmol/mol

*PF*C2H6[NMC-FID] = 0.020

*x*NMHC = 132.3 µmol/mol

(iii) For penetration fractions determined using an NMC configuration as outlined in section § 1065.365(f), use the following equation:

Where:*x*NMHC = concentration of NMHC.

*x*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 CH4 penetration fraction, according to § 1065.365(f).

*x*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 response factor and penetration fraction, according to § 1065.365(f).

*RF*CH4[THC-FID] = response factor of THC FID to CH4, according to § 1065.360(d). Example:

*x*THC[THC-FID]cor = 150.3 µmol/mol

*PF*CH4[NMC-FID] = 0.990

*x*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 *x*NMHC using the THC
analyzer's response factor (*RF*) for CH4, from § 1065.360,
and the initial THC contamination and dry-to-wet corrected THC
concentration *x*THC[THC-FID]cor as determined in paragraph
(a) of this section as follows:

*x*NMHC = concentration of NMHC.

*x*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 CH4.

*x*CH4 = concentration of CH4, dry-to-wet corrected, as measured by the GC-FID or FTIR. Example:

*x*THC[THC-FID]cor = 145.6 µmol/mol

*RF*CH4[THC-FID] = 0.970

*x*CH4 = 18.9 µmol/mol

*x*NMHC = 145.6−0.970 · 18.9

*x*NMHC = 127.3 µmol/mol

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

*x*NMHC = concentration of NMHC.

*x*HCi = the C1-equivalent concentration of hydrocarbon species

*i*as measured by the FTIR, not corrected for initial contamination.

*x*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*C2H6 = 4.9 µmol/mol

*x*C2H4 = 0.9 µmol/mol

*x*C2H2 = 0.8 µmol/mol

*x*C3H8 = 0.4 µmol/mol

*x*C3H6 = 0.5 µmol/mol

*x*C4H10 = 0.3 µmol/mol

*x*CH2O = 0.8 µmol/mol

*x*C2H4O = 0.3 µmol/mol

*x*C2H2O2 = 0.1 µmol/mol

*x*CH4O = 0.1 µmol/mol

*x*NMHC = 4.9 + 0.9 + 0.8 + 0.4 + 0.5 + 0.3 + 0.8 + 0.3 + 0.1 + 0.1

*x*NMHC = 9.1 µmol/mol

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

(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 or FTIR, calculate *x*NMNEHC using the THC
analyzer's response factors (*RF*) for CH4 and C2H6, from §
1065.360, and the initial contamination and dry-to-wet corrected
THC concentration *x*THC[THC-FID]cor as determined in
paragraph (a) of this section as follows:

*x*NMNEHC = concentration of NMNEHC.

*x*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 CH4.

*x*CH4 = concentration of CH4, dry-to-wet corrected, as measured by the GC-FID or FTIR.

*RF*C2H6[THC-FID] = response factor of THC-FID to C2H6.

*x*C2H6 = the C1-equivalent concentration of C2H6, dry-to-wet corrected, as measured by the GC-FID or FTIR. Example:

*x*THC[THC-FID]cor = 145.6 µmol/mol

*RF*CH4[THC-FID] = 0.970

*x*CH4 = 18.9 µmol/mol

*RF*C2H6[THC-FID] = 1.02

*x*C2H6 = 10.6 µmol/mol

*x*NMHC = 145.6 - 0.970 · 18.9 - 1.02 · 10.6

*x*NMHC = 116.5 µmol/mol

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

*x*NMNEHC = concentration of NMNEHC.

*x*HCi = the C1-equivalent concentration of hydrocarbon species

*i*as measured by the FTIR, not corrected for initial contamination.

*x*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*C2H4 = 0.9 µmol/mol

*x*C2H2 = 0.8 µmol/mol

*x*C3H8 = 0.4 µmol/mol

*x*C3H6 = 0.5 µmol/mol

*x*C4H10 = 0.3 µmol/mol

*x*CH2O = 0.8 µmol/mol

*x*C2H4O = 0.3 µmol/mol

*x*C2H2O2 = 0.1 µmol/mol

*x*CH4O = 0.1 µmol/mol

*x*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) *CH*4 *determination.* Use one of the following
methods to determine CH4 concentration, xCH4:

(1) For nonmethane cutters, calculate *x*CH4 using the
nonmethane cutter's penetration fraction (*PF*) of CH4 and the
response factor penetration fraction (*RFPF*) of C2H6 from §
1065.365, the response factor (*RF*) of the THC FID to CH4
from § 1065.360, the initial THC contamination and dry-to-wet
corrected THC concentration *x*THC[THC-FID]cor as determined
in paragraph (a) of this section, and the dry-to-wet corrected CH4
concentration *x*THC[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):

Where:*x*CH4 = concentration of CH4.

*x*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.

*x*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 response factor and penetration fraction of the nonmethane cutter, according to § 1065.365(d).

*RF*CH4[THC-FID] = response factor of THC FID to CH4, according to § 1065.360(d). Example:

*x*THC[NMC-FID]cor = 10.4 µmol/mol

*x*THC[THC-FID]cor = 150.3 µmol/mol

*RFPF*C2H6[NMC-FID] = 0.019

*RF*CH4[THC-FID] = 1.05

*x*CH4 = 7.69 µmol/mol

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

Where:*x*CH4 = concentration of CH4.

*x*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.

*x*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 penetration fraction, according to § 1065.365(e).

*RF*CH4[THC-FID] = response factor of THC FID to CH4, according to § 1065.360(d).

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

*x*THC[NMC-FID]cor = 10.4 µmol/mol

*x*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) For penetration fractions determined using an NMC configuration as outlined in § 1065.365(f), use the following equation:

Where:*x*CH4 = concentration of CH4.

*x*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.

*x*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 response factor and penetration fraction of the nonmethane cutter, according to § 1065.365(f).

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

*RF*CH4[THC-FID] = response factor of THC FID to CH4, according to § 1065.360(d). Example:

*x*THC[NMC-FID]cor = 10.4 µmol/mol

*x*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, *x*CH4 is the actual dry-to-wet
corrected CH4 concentration as measured by the analyzer.

(e) *C*2*H*6 *determination.* For a GC-FID or
FTIR, *x*C2H6 is the C1-equivalent, dry-to-wet corrected C2H6
concentration as measured by the analyzer.