eCFR Reference Browser

---

title: "40 CFR §90.329"

source: "https://www.ecfr.gov/current/title-40/section-90.329"

title_number: "40"

volume_number: "22"

chapter_number: "Unknown"

subchapter_code: "C"

subchapter_subject: "AIR PROGRAMS (CONTINUED)"

part_code: "90"

part_subject: "CONTROL OF EMISSIONS FROM NONROAD SPARK-IGNITION ENGINES AT OR BELOW 19 KILOWATTS"

subpart_code: "D"

subpart_subject: "Emission Test Equipment Provisions"

section_number: "90.329"

section_subject: "Catalyst thermal stress test."

cfr_reference: "40 CFR 90.329"

title_name: "Title 40"

title_subject: "Protection of Environment"

parts_covered: "Parts 87 to 95"

revised_date: "Revised as of July 1, 2017"

publication_date: "As of July 1, 2017"

contains_description: "Containing a codification of documents of general applicability and future effect"

publication_info: "Published by the Office of the Federal Register National Archives and Records Administration as a Special Edition of the Federal Register"

---

(a)Oven characteristics. The oven used for thermally stressing the test catalyst must be capable of maintaining a temperature of 500 ±5 °C and 1000 ±10 °C.

(b)Evaluation gas composition. (1) A synthetic exhaust gas mixture is used for evaluating the effect of thermal stress on catalyst conversion efficiency.

(2)The synthetic exhaust gas mixture must have the following composition:

(c)Phase 2 engines. The catalyst thermal stress test is not required for engine families certified to the Phase 2 standards.

§90.329 - Catalyst thermal stress test.