View all text of Subjgrp 32 [§ 1065.370 - § 1065.378]
§ 1065.372 - NDUV analyzer HC and H2O interference verification.
(a) Scope and frequency. If you measure NO
(b) Measurement principles. Hydrocarbons and H
(c) System requirements. A NO
(d) Procedure. Perform the interference verification as follows:
(1) Start, operate, zero, and span the NO
(2) We recommend that you extract engine exhaust to perform this verification. Use a CLD that meets the specifications of subpart C of this part to quantify NO
(3) Upstream of any sample dryer, if one is used during testing, introduce the engine exhaust to the NDUV analyzer.
(4) Allow time for the analyzer response to stabilize. Stabilization time may include time to purge the transfer line and to account for analyzer response.
(5) While all analyzers measure the sample's concentration, record 30 seconds of sampled data, and calculate the arithmetic means for the three analyzers.
(6) Subtract the CLD mean from the NDUV mean.
(7) Multiply this difference by the ratio of the flow-weighted mean HC concentration expected at the standard to the HC concentration measured during the verification. The analyzer meets the interference verification of this section if this result is within ±2% of the NO
(e) Exceptions. The following exceptions apply:
(1) You may omit this verification if you can show by engineering analysis that for your NO