[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: 40CFR1065.270]

[Page 710]
 
                   TITLE 40--PROTECTION OF ENVIRONMENT
 
         CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
 
PART 1065_ENGINE-TESTING PROCEDURES--Table of Contents
 
                    Subpart C_Measurement Instruments
 
Sec.  1065.270  Chemiluminescent detector.

    (a) Application. You may use a chemiluminescent detector (CLD) to 
measure NOX concentration in raw or diluted exhaust for batch 
or continuous sampling. We generally accept a CLD for NOX 
measurement, even though it measures only NO and NO2, when 
coupled with an NO2-to-NO converter, since conventional 
engines and aftertreatment systems do not emit significant amounts of 
NOX species other than NO and NO2. Measure other 
NOX species if required by the standard-setting part. While 
you may also use other instruments to measure NOX, as 
described in Sec.  1065.272, use a reference procedure based on a 
chemiluminescent detector for comparison with any proposed alternate 
measurement procedure under Sec.  1065.10.
    (b) Component requirements. We recommend that you use a CLD that 
meets the specifications in Table 1 of Sec.  1065.205. Note that your 
CLD-based system must meet the quench verification in Sec.  1065.370 and 
it must also meet the linearity verification in Sec.  1065.307. You may 
use a heated or unheated CLD, and you may use a CLD that operates at 
atmospheric pressure or under a vacuum. You may use a CLD 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. Place upstream of the CLD 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 all CLD temperatures to 
prevent aqueous condensation. To remove humidity from a sample upstream 
of a CLD, use one of the following configurations:
    (1) Connect a CLD 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 a CLD downstream of any dryer or thermal chiller that 
meets the verification in Sec.  1065.376.
    (e) Response time. You may use a heated CLD to improve CLD response 
time.