§ 27.204 Minimum concentration by security issue. ( a ) *Release chemicals* — ( 1 ) *Release-toxic chemicals.* If a release-toxic chemical of interest is present in a mixture, and the concentration of the chemical is equal to or greater than one percent (1%) by weight, the facility shall count the amount of the chemical of interest in the mixture toward the STQ. If a release-toxic chemical of interest is present in a mixture, and the concentration of the chemical is less than one percent (1%) by weight of the mixture, the facility need not count the amount of that chemical in the mixture in determining whether the facility possesses the STQ. Except for oleum, if the concentration of the chemical of interest in the mixture is one percent (1%) or greater by weight, but the facility can demonstrate that the partial pressure of the regulated substance in the mixture (solution) under handling or storage conditions in any portion of the process is less than 10 millimeters of mercury (mm Hg), the amount of the substance in the mixture in that portion of a vessel need not be considered when determining the STQ. The facility shall document this partial pressure measurement or estimate.
( 2 ) *Release-flammable chemicals.* If a release-flammable chemical of interest is present in a mixture in a concentration equal to or greater than one percent (1%) by weight of the mixture, and the mixture has a NFPA flammability hazard rating of 4, the facility shall count the entire amount of the mixture toward the STQ. Except as provided in § 27.203(b)(1)(v) for fuels that are stored in aboveground tank farms (including farms that are part of pipeline systems), if a release-flammable chemical of interest is present in a mixture in a concentration equal to or greater than one percent (1%) by weight of the mixture, and the mixture has a NFPA flammability hazard rating of 1, 2, or 3, the facility need not count the mixture toward the STQ. The flammability hazard ratings are defined in NFPA 704: Standard System for the Identification of the Hazards of Materials for Emergency Response [2007 ed.]. The Director of the Federal Register approves the incorporation by reference of this standard in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. You may obtain a copy of the incorporated standard from the NFPA at 1 Batterymarch Park, Quincy, MA 02169-7471 or *http://www.nfpa.org .* You may inspect a copy of the incorporated standard at the Department of Homeland Security, 1621 Kent Street, 9th Floor, Rosslyn, VA (please call 703-235-0709 to make an appointment), or at the National Archives and Records Administration (NARA). For information on the availability of material at NARA, call 202-741-6030, or go to *http://www.archives.gov/federal_register/code_of_federal_regulations/ibr_locations.html .* If a release-flammable chemical of interest is present in a mixture, and the concentration of the chemical is less than one percent (1%) by weight, the facility need not count the mixture in determining whether the facility possesses the STQ.
( 3 ) *Release-explosive chemicals.* For each release-explosive chemical of interest, a facility shall count the total quantity of all commercial grades of the chemical of interest toward the STQ, unless a specific minimum concentration is assigned in the Minimum Concentration column of appendix A to part 27, in which case the facility should count the total quantity of all commercial grades of the chemical at the specified minimum concentration.
( b ) *Theft and diversion chemicals* — ( 1 ) *Theft/Diversion-Chemical Weapons (CW) and Chemical Weapons Precursors (CWP) chemicals.* Where a theft/diversion-CW/CWP chemical of interest is not designated by “CUM 100g” in appendix A, and the chemical is present in a mixture at or above the minimum concentration amount listed in the Minimum Concentration column of appendix A to part 27, the facility shall count the entire amount of the mixture toward the STQ.
( 2 ) *Theft/Diversion-Weapon of Mass Effect (WME) chemicals.* If a theft/diversion-WME chemical of interest is present in a mixture at or above the minimum concentration amount listed in the Minimum Concentration column of appendix A to part 27, the facility shall count the entire amount of the mixture toward the STQ.
( 3 ) *Theft/Diversion-Explosives/Improvised Explosive Device Precursor (EXP/IEDP) chemicals.* For each theft/diversion-EXP/IEDP chemical of interest, a facility shall count the total quantity of all commercial grades of the chemical toward the STQ, unless a specific minimum concentration is assigned in the Minimum Concentration column of appendix A to part 27, in which case the facility should count the total quantity of all commercial grades of the chemical at the specified minimum concentration.
( c ) *Sabotage and contamination chemicals.* For each sabotage and contamination chemical of interest, a facility shall count the total quantity of all commercial grades of the chemical toward the STQ.
[72 FR 65419, Nov. 20, 2007, as amended at 86 FR 41891, Aug. 4, 2021]