The practicable options can be summarized in
the following categories:
Detection & Alarm Systems
Detection & Fixed Suppression Systems
Fixed Foam Pourer/Base Injection Systems
Fixed & Mobile Foam Monitors
External Brigade Assistance
Floating roof tanks
Detection and foam suppression stand alone units.
Usually Nitrogen powered with telemetry control
back to the control room. Small foam vessels are
located on the roof to protect the rimseal area.
The advantage of the combined detection system
is its speed of response.
Over the top pourers. Provide low expansion
foam to the rimseal foam dam area. Can be fed
from a central foam proportioning system or from
a mobile foam tender. Can be linked to linear heat
detection or can be manual.
Williams Fire & Hazard Control have been carry-
ing out considerable R&D into cone and internal
floating roof tank fires, following a series of these
over the last years.
It was perceived by Dwight Williams and his
team that foaming the surface of the product prior
to extinguishing the fires on these tanks when
they are burning at the vents or fishmouth tears
can over time cause an explosion inside the tank
that is likely to violently blow the roof of the tank.
It was during this research that they fell upon
the concept of a dual agent foam / dry chemical
chamber fitted in place of one of the foam
chambers if fitted to these tanks, thereby allowing
firefighters to purge the atmosphere inside the
tank vapour space during the fire and extinguish-
ing the fire in a matter of seconds.
Cone roof tanks
Over the top pourers, protecting the full fuel
surface and incorporating a vapour seal between
the tank and supply pipework. Can be subject to
explosion damage.
Base foam injection systems are situated
remotely from the explosion area. Rely on forcing
low expansion foam through the base of the tank
up to the fuel surface. Unsuitable for foam
destructive products.
Semi subsurface base foam injection
systems incorporate a high back pressure genera-
tor and an internal floating delivery hose to apply
foam to the surface of the tanks containing foam
destructive chemicals such as Methanol or
Acetone. A gentle foam application results in
faster extinguishment. A plunging foam applica-
tion is a less efficient method of delivery.
48 INTERNATIONAL FIRE PROTECTION
STORAGE TANK FIRE PROTECTION
STORAGE TANKS
Over-the-top foam
generator
Foam concentrate
Foam
pump
Foam tank
Storage tank
Water
Water pump
Pressure
proportioner
PP(W)
Top pourers
Svenska Skum semi sub
surface foam injection
unit
Williams Fire & Hazard dual agent foam
chamber

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