Vapour Recovery System
Abbreviation: VRS
Closed-loop return of cargo vapour from ship to shore (or shore to ship) during loading to prevent atmospheric venting.
In practice
Common at MARPOL VOC-controlled terminals (US gulf, EU regulated ports). Cargo officer verifies the vapour return arm connection and the flame arrestor before transfer. Pressure imbalance between ship and shore is the routine operational hazard.
Regulatory detail & full definition
Vapour recovery is the closed-loop return of cargo vapour between ship and shore during loading so that hydrocarbon vapour is captured rather than vented to atmosphere. It is required at terminals where volatile-organic-compound emissions are regulated (US OPA-90 Section 4115; the EU VOC Directive). The vapour-return line connects through a flame arrestor and detonation arrestor, and the ship's inert-gas-system pressure is balanced against the shore receiver. It is especially important for gasoline, MTBE and volatile chemical cargoes.
Authoritative source: ISGOTT 6th edition ↗
Related
Source: OPA-90 Section 4115; ISGOTT Ch. 11
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