4 The generation of toxic and explosive gases
in the event of anaerobic conditions is present to varying degrees
in each system. It is evident from the foregoing that anaerobic conditions
in sewage systems leading to the production of toxic and flammable
gases is an unacceptable hazard within the confined boundaries of
ship.
5 In general sewage systems should be of a design
which will avoid the problems outlined in these guidelines. The primary
safety features should be incorporated in the design and operation
of a sewage system and the barriers between the sewage gases such
as water traps of the toilet bowls, ventilation of the pipework and
tanks should only be considered a secondary means of protection. The
primary objective should be in the prevention of the production of
hazardous gases within the systems.