[Code of Federal Regulations]
[Title 40, Volume 31]
[Revised as of July 1, 2007]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR1065.272]

[Page 710-711]
 
                   TITLE 40--PROTECTION OF ENVIRONMENT
 
         CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
 
PART 1065_ENGINE-TESTING PROCEDURES--Table of Contents
 
                    Subpart C_Measurement Instruments
 
Sec.  1065.272  Nondispersive ultraviolet analyzer.

    (a) Application. You may use a nondispersive ultraviolet (NDUV) 
analyzer to measure NOX concentration in raw or diluted 
exhaust for batch or continuous sampling. We generally accept an NDUV 
for NOX measurement, even though it measures only NO and 
NO2, since conventional engines and aftertreatment systems do 
not emit significant amounts of other NOX species. Measure 
other NOX species if required by the standard-setting part.
    (b) Component requirements. We recommend that you use an NDUV 
analyzer that meets the specifications in Table 1 of Sec.  1065.205. 
Note that your NDUV-based system must meet the verifications in Sec.  
1065.372 and it must also meet the linearity verification in Sec.  
1065.307. You may use a NDUV analyzer that has compensation algorithms 
that are functions of other gaseous measurements and the engine's known 
or assumed fuel properties. The target value for any compensation 
algorithm is 0.0% (that is, no bias high and no bias low), regardless of 
the uncompensated signal's bias.
    (c) NO2-to-NO converter. If your NDUV analyzer measures only NO, 
place upstream of the NDUV analyzer an internal or external 
NO2-to-NO converter that meets the verification in Sec.  
1065.378. Configure the converter with a bypass to facilitate this 
verification.
    (d) Humidity effects. You must maintain NDUV temperature to prevent

[[Page 711]]

aqueous condensation, unless you use one of the following 
configurations:
    (1) Connect an NDUV downstream of any dryer or chiller that is 
downstream of an NO2-to-NO converter that meets the 
verification in Sec.  1065.378.
    (2) Connect an NDUV downstream of any dryer or thermal chiller that 
meets the verification in Sec.  1065.376.

                       O2 Measurements