85.2224—Exhaust analysis system—EPA 81.
(a) Applicability.
The requirements of this subsection apply to short tests conducted under Emissions Performance Warranty through December 31, 1993. The requirements of § 85.2225 apply concurrently until December 31, 1993, after which the requirements of § 85.2225 are solely in effect. The following exceptions apply: In a state where the Administrator has approved a SIP revision providing for implementation of a basic centralized program meeting the requirements of part 51, subpart S of this chapter, according to the schedule specified in § 51.373 of this chapter, the requirements of this section are concurrently in effect until June 30, 1994 for 1995 and earlier model year vehicles or engines; in a state where the Administrator has approved a SIP revision providing for implementation of an enhanced program meeting the requirements of part 51, subpart S of this chapter, according to the schedule specified in § 51.373 of this chapter, the requirements of this section are concurrently in effect until December 31, 1995 for 1995 and earlier model year vehicles or engines.
(b) Sampling system—
(1) General requirements.
The exhaust sampling system shall consist of a sample probe, moisture separator and analyzers for HC and CO.
(2) Dual sample probe requirements.
If used, a dual sample probe must provide equal flow in each leg. The equal flow criterion is considered to be met if the flow rate in each leg of the probe (or an identical model) has been measured under two sample flow rates (the normal rate and a rate equal to the onset of low flow), and if the flow rates in each of the legs are found to be equal to each other (±15%).
(c) Analyzers—
(1) Accuracy.
The HC analyzer shall have an accuracy of ±15 ppm at 200 to 220 ppm concentration HC (as hexane). The CO analyzer shall have an accuracy of ±0.1% CO from 1.0% to 1.2% concentration.
(3) Drift.
Analyzer drift (up-scale and down-scale zero and span wander) shall not exceed ±0.1% CO and ±15 ppm HC (as hexane) on the lowest range capable of reading 1.0% or 200 ppm HC (as hexane) during a one-hour period.