---identifier: "/us/cfr/t33/s157.12a"source: "ecfr"legal_status: "authoritative_unofficial"title: "33 CFR § 157.12a - Definitions."title_number: 33title_name: "Navigation and Navigable Waters"section_number: "157.12a"section_name: "Definitions."chapter_name: "COAST GUARD, DEPARTMENT OF HOMELAND SECURITY"subchapter_number: "O"subchapter_name: "POLLUTION"part_number: "157"part_name: "RULES FOR THE PROTECTION OF THE MARINE ENVIRONMENT RELATING TO TANK VESSELS CARRYING OIL IN BULK"positive_law: falsecurrency: "2026-03-24"last_updated: "2026-03-24"format_version: "1.1.0"generator: "[email protected]"authority: "33 U.S.C. 1903; 46 U.S.C. 3703, 3703a (note); Department of Homeland Security Delegation No. 0170.1. Subparts G, H, and I are also issued under section 4115(b), Pub. L. 101-380, 104 Stat. 520; Pub. L. 104-55, 109 Stat. 546."regulatory_source: "CGD 74-32, 40 FR 48283, Oct. 14, 1975, unless otherwise noted."cfr_part: "157"---
Identifier
/us/cfr/t33/s157.12a
Currency
2026-03-24
Positive Law
No
Updated
2026-03-24
Chapter
Coast Guard, Department of Homeland Security
Authority
33 U.S.C. 1903; 46 U.S.C. 3703, 3703a (note); Department of Homeland Security Delegation No. 0170.1. Subparts G, H, and I are also issued under section 4115(b), Pub. L. 101-380, 104 Stat. 520; Pub. L.... 33 U.S.C. 1903; 46 U.S.C. 3703, 3703a (note); Department of Homeland Security Delegation No. 0170.1. Subparts G, H, and I are also issued under section 4115(b), Pub. L. 101-380, 104 Stat. 520; Pub. L. 104-55, 109 Stat. 546.
# 157.12a Definitions.As used in §§ 157.12a through 157.12g—*Control section* means a unit in a monitoring system composed of the items specified in § 157.12d(a)(4)(viii).*Control unit* means a device that receives automatic signals of oil content of the effluent ppm, flow rate of discharge m<sup>3</sup>/hour, ship's speed in knots, ship's position-latitude and longitude, date and time (GMT, Greenwich Mean Time), and status of the overboard discharge control. The control unit makes automatic recordings of data as specified in § 157.12d(h)(2).*Oil discharge monitoring and control system* or *monitoring system* means a system that monitors the discharge into the sea of oily ballast or other oil-contaminated water from the cargo tank areas and comprises the items specified in § 157.12d(a)(4).*Overboard discharge control* means a device that automatically initiates the sequence to stop the overboard discharge of the effluent in alarm conditions and prevents the discharge throughout the period the alarm condition prevails. The device may be arranged to close the overboard valves or to stop the relevant pumps, as appropriate.*PPM* means parts of oil per million parts of water by volume.*Starting interlock* means a facility that prevents the initiation of the opening of the discharge valve or the operation of other equivalent arrangements before the monitoring system is fully operational when use of the monitoring system is required by the Convention.[USCG-2004-18939, 74 FR 3379, Jan. 16, 2009]