High-expansion foam systems
Any required fixed high-expansion foam system in machinery spaces is to be capable of rapidly discharging through fixed discharge outlets a quantity of foam sufficient to fill the greatest space to be protected at a rate of at least 1 m in depth per minute. The quantity of foam-forming liquid available is to be sufficient to produce a volume of foam equal to five times the volume of the largest space to be protected.
The expansion ratio of the foam is not to exceed 1000 to 1.
Alternative arrangements and discharge rates will be permitted provided that equivalent protection is achieved.
Supply ducts for delivering foam, air intakes to the foam generator and the number of foam-generating units are to be such as will provide effective foam production and distribution.
The arrangement of the foam generator delivery ducting is to be such that a fire in the protected space will not affect the foam-generating equipment.
The foam generator, its sources of power supply, foam-forming liquid and means of controlling the system are to be readily accessible and simple to operate and are to be grouped in as few locations as possible at positions not likely to be cut off by fire in the protected space.
Foam concentrates carried for use in fixed foam fire-extinguishing systems are to be of an approved type. They are to be tested at least twice during each five year period to verify that they remain fit for service. Evidence in the form of a report from the foam manufacturer or an independent laboratory will be accepted.