### U.S. Code of Federal Regulations

Regulations most recently checked for updates: Mar 30, 2023

(a) *THC determination and initial THC/CH**contamination corrections.* (1) If we require you to determine THC emissions, calculate *x**x*

*x*

*x*

*x*

*x*

(2) For the NMHC determination described in paragraph (b) of this section, correct *x**x*

(3) For the NMNEHC determination described in paragraph (c) of this section, correct *x**x*

(4) For the CH*x*

(5) You may calculate THC as the sum of NMHC and CH

(6) You may calculate THC as the sum of NMNEHC, C

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

(1) If you do not measure CH

(2) For nonmethane cutters, calculate χ*PF**RFPF**RF*

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

*x*

*x*

*x*

*RF*

*RFPF*

*x*

*x*

*RFPF*

*RF*

*x*

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

*x*

*x*

*PF*

*x*

*PF*

*x*

*PF*

*x*

*PF*

*x*

(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*

*x*

*PF*

*x*

*RFPF*

*RF*

*x*

*PF*

*x*

*RFPF*

*RF*

*x*

(3) For a GC-FID or FTIR, calculate χ*RF*

*x*

*x*

*RF*

*x*

*x**RF**x**x**x*

(4) For an FTIR, calculate χ

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

*i*, dry-to-wet corrected, as measured by the FTIR.

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

(1) Calculate *x*

(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 ethane, 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*RF**RF*

*RF*

*RF*

*RF*

*RF*

(3) For an FTIR, calculate *x*

*x*

*x*

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

*x*

*i,*dry-to-wet corrected, as measured by the FTIR.

*x*

*x*

*x*

*x*

*x*

*x*

*x*

*x*

*x*

*x*

*x*

(d) *CH** determination.* Use one of the following methods to determine methane concentration, χ

(1) For nonmethane cutters, calculate χ*PF**RFPF**RF*

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

*x*

*x*

*x*

*RFPF*

*RF*

*x*

*x*

*RFPF*

*RF*

*x*

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

*x*

*x*

*x*

*PF*

*RF*

*PF*

*x*

*x*

*PF*

*RF*

*PF*

*x*

(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*

*x*

*x*

*RFPF*

*PF*

*RF*

*x*

*x*

*RFPF*

*PF*

*RF*

*x*

(2) For a GC-FID or FTIR, χ

(e) *C**H**determination.* For a GC-FID or FTIR, χ