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In the ‘HotFoam’ system the foam generator has no fan/blower. The air is drawn in with a jet of the foam/water solution in a similar manner to a standard mixer nozzle.
Expansion
Ratio maximum of 1000 to 1
This
is the maximum expansion ratio
allowable under SOLAS. It compares with ratios of 12:1 for traditional low
expansion foams and 20:1 for AFFF.
High Expansion foams are produced
from synthetic detergents such as Ammonium Lauryl Esther Sulphate. Air is blown
through a net fabric which is wetted by water which has picked up foam compound
by entrainment.
Foam production may be adversely
affected by smoke in the air steam. Some manufacturers say their products are
not affected.
The foam is persistent, insulates
well and absorbs radiant heat. Some of the foam expands to steam at the fire,
with an expansion ratio of 1700 to 1, which gives an oxygen content of below 8%
by volume and so smothers the fire. The latent heat required is removed from
the fire, producing a cooling effect.
The foam generating equipment
must be readily accessible and separate from the protected space.
The rate of application must
ensure the foam level in the engine room rises at least 1 metre per minute.
The quantity of foam forming
liquid must be able to supply five
times the volume of the protected space.
Foam generating
equipment and controls must be outside the protected space, readily accessible
and simple to operate. Ducting material must be at least 5mm thick. Ducts must
be fitted with automatically operated dampers installed in the openings of the
boundary bulkheadsIn the ‘HotFoam’ system the foam generator has no fan/blower. The air is drawn in with a jet of the foam/water solution in a similar manner to a standard mixer nozzle.
The foam produced uses the air and
combustion gases within the protected space – hence the name HotFoam. [Unitor].
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I liked the practical side of this discussion, particularly the emphasis on maintaining stable operating temperatures. In many industrial machines, equipment may run continuously for several hours, so even a small amount of excess heat can accumulate over time. A properly selected water oil cooler can help remove this unwanted heat and support more consistent operation. One point I would add is that the cooling water circuit should also be monitored. Poor water quality or deposits inside the passages may reduce heat-transfer efficiency. Checking flow rates and cleaning the system at suitable intervals could make a noticeable difference. It would be useful if future articles also explained how users can recognize early signs that an oil cooler is becoming less effective before the machine starts experiencing serious temperature-related problems.
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