StacksVerified U.S. regulatory reference

40 CFR Part 98, Table I-17

Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov
For each stack system for which you use the “stack test method” to calculate annual emissions, you must measure the following:If emissions are detected intermittently, use thefollowing procedures:If emissions are not detected, use thefollowing procedures:
Expected By-products: CF4 C2 F6 CHF3 CH2 F2 CH3 FUse the measured concentration for “Xksm” in Equation I-18 when available and use one-half of the field detection limit you determined for the fluorinated GHG according to § 98.94(j)(2) for the value of “Xksm” when the fluorinated GHG is not detectedUse one-half of the field detection limit you determined for the fluorinated GHG according to § 98.94(j)(2) for the value of “Xksm” in Equation I-18.
Possible By-products: C3 F8 C4 F6 c-C4 F8 C5 F8Use the measured concentration for “Xksm” in Equation I-18 when available and use one-half of the field detection limit you determined for the fluorinated GHG according to § 98.94(j)(2) for the value of “Xksm” when the fluorinated GHG is not detectedAssume zero emissions for that fluorinated GHG for the tested stack system.

[78 FR 68234, Nov. 13, 2013]