REQUIREMENTS FOR IGS NON-RETURN DEVICES
SOLAS Chapter 11-2, Regulation 62, provides the requirements for the non-return devices installed in the inert gas main of a
typical system.
Regulation 62 requires that the inert gas system is equipped with two non-return devices, one of which shall be a water seal, to
prevent the return of hydrocarbon vapour to the gas-safe spaces.
In addition, Regulation 62 requires that the arrangement of the deck seal shall be such that it will prevent the backflow of
hydrocarbon vapours and will ensure the proper functioning of the seal under operating conditions.
The IMO "Guidelines for Inert Gas Systems", Sections 3.6 and 3.7, indicate the design considerations, and provide details on the
function, of various types of deck water seals.