StacksVerified U.S. regulatory reference

40 CFR §65.85

Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗
  1. (a)Vapor tightness. For the purposes of demonstrating vapor tightness to determine compliance with § 65.84(c)(2), the following procedures and equipment shall be used:
    1. (1)The pressure test procedures specified in Method 27 of appendix A of 40 CFR part 60; and
    2. (2)A pressure measurement device that has a precision of ±2.5 millimeters of mercury (0.10 inch) or better and that is capable of measuring above the pressure at which the tank truck or railcar is to be tested for vapor tightness.
  2. (b)Engineering assessment. Engineering assessment to determine if a vent stream is halogenated or flow rate of a gas stream includes, but is not limited to, the following examples:
    1. (1)Previous test results, provided the tests are representative of current operating practices at the process unit.
    2. (2)Bench-scale or pilot-scale test data representative of the process under representative operating conditions.
    3. (3)Maximum flow rate or halogen emission rate specified or implied within a permit limit applicable to the process vent.
    4. (4)Design analysis based on accepted chemical engineering principles, measurable process parameters, or physical or chemical laws or properties.
    5. (5)All data, assumptions, and procedures used in the engineering assessment shall be documented.
  3. (c)Halogenated vent stream determination. In order to determine whether a vent stream is halogenated, the mass emission rate of halogen atoms contained in organic compounds shall be calculated as specified in paragraphs (c)(1) and (2) of this section.
    1. (1)The vent stream concentration of each organic compound containing halogen atoms (parts per million by volume by compound) shall be determined based on any of the following procedures:
      1. (i)Process knowledge that no halogen or hydrogen halides are present in the vent stream; or
      2. (ii)Applicable engineering assessment as specified in paragraph (b) of this section; or
      3. (iii)Concentration of organic compounds containing halogens measured by Method 18 of appendix A of 40 CFR part 60; or
      4. (iv)Any other method or data that have been validated according to the applicable procedures in Method 301 of appendix A of 40 CFR part 63.
    2. (2)Equation 85-1 of this section shall be used to calculate the mass emission rate of halogen atoms: