{"data":{"id":"us/33-cfr-154.2109","jurisdiction":"us","citation":"33 CFR 154.2109","heading":"Vapor recovery and vapor destruction units.","body":"Paragraphs (a), (b), and (e) of this section apply only to facilities collecting vapors of flammable, combustible, or non-high flash point liquid cargoes.\n(a) The inlet to a vapor recovery unit that receives vapor that has not been inerted, enriched, or diluted in accordance with 33 CFR 154.2107 must be fitted with a detonation arrester.\n(b) The inlet to a vapor destruction unit must—\n(1) Have a liquid seal that meets the requirements of paragraph (e) of this section, except as specified by paragraph (b)(3) of this section; and\n(2) Have two quick-closing stop valves installed in the vapor line. One of them must be installed upstream of the detonation arrester required by paragraph (c)(2) of this section. The quick-closing stop valves must—\n(i) Close within 30 seconds after detection of a condition that requires the closing of these two quick-closing stop valves by a control component required by this subpart for a vapor control system (VCS) with a vapor destruction unit;\n(ii) Close automatically if the control signal is lost;\n(iii) Have a local valve position indicator or be designed so that the valve position is readily determined from the valve handle or valve stem position; and\n(iv) If the valve seat is fitted with resilient material, be a Category A valve as defined by 46 CFR 56.20-15 and not allow appreciable leakage when the resilient material is damaged or destroyed; and\n(3) Instead of a liquid seal as required by paragraph (b)(1) of this section, have the following:\n(i) An anti-flashback burner accepted by the Commandant and installed at each burner within the vapor destruction unit; and\n(ii) A differential pressure sensor that activates the quick-closing stop valves as required by paragraph (b)(2) of this section upon sensing a reverse flow condition.\n(c) A vapor destruction unit must—\n(1) Not be within 30 meters (98.8 feet) of any tank vessel berth or mooring at the facility;\n(2) Have a detonation arrester fitted in the inlet vapor line; and\n(3) Activate an alarm that satisfies the requirements of 33 CFR 154.2100(e) and shut down when a flame is detected on the detonation arrester.\n(d) When a vapor destruction unit shuts down or has a flame-out condition, the vapor destruction unit control system must—\n(1) Activate and close the quick-closing stop valves required by paragraph (b)(2) of this section;\n(2) Close the remotely operated cargo vapor shutoff valve required by 33 CFR 154.2101(a); and\n(3) Automatically shut down any vapor-moving devices installed in the VCS.\n(e) If a liquid seal is installed at the inlet to a vapor destruction unit, then—\n(1) The liquid used in the liquid seal must be compatible with the vapors being controlled;\n(2) For partially or totally soluble cargoes that can polymerize in solution, there must be an adequate amount of inhibitor in the liquid seal;\n(3) The liquid seal must be compatible with the design of the VCS and must not contribute to the flammability of the vapor stream; and\n(4) The liquid seal must have a low-level alarm and a low-low level shutdown.","path":["Title 33—Navigation and Navigable Waters","CHAPTER I—COAST GUARD, DEPARTMENT OF HOMELAND SECURITY","SUBCHAPTER O—POLLUTION","PART 154—FACILITIES TRANSFERRING OIL OR HAZARDOUS MATERIAL IN BULK","Subpart P—Marine Vapor Control Systems"],"source_url":"https://www.ecfr.gov/api/versioner/v1/full/2026-08-25/title-33.xml","current_through":"2026-08-25","vintage":"","retrieved_at":"2026-08-27T02:25:35Z","sha256":"a34a74453d2f6fd230acfdadf2984b01bf1f3c6291deab61e72642545a5d98ee","source_id":"us-cfr","stale":true,"prev":"us/33-cfr-154.2108","next":"us/33-cfr-154.2110"},"notice":"GroundRules: Original legal text. Not legal advice."}