Mobile equipment such as monitor trailers
and refinery vehicles with monitors, as with
floating roof tanks require a critical deployment
factor involving a sufficient quantity of foam
concentrate and water in the correct application
rate or deployment will not succeed
It is in this area that most development has taken
place with the realization that fully involved tank
fires can be successfully extinguished rather than
left to burn. The use of unaspirated foam applied
by very high flow rate monitors also represents a
paradigm shift from the days of aspirated only
application. The current "record" tank fire is the
Orion. The incident occurred in 2001 and was suc-
cessfully extinguished by a team from Williams Fire
& Hazard Control in 65 minutes using an applica-
tion rate of 8.55 l/m2/min. The tank was a massive
82.4 metres diameter and it required a flow rate of
45,000 lpm. Given these big numbers it is easy to
see why foam concentrates are becoming ever
more concentrated with 1% taking over from 3%
and 6%. This means that less product is required to
be stored and transported should the worst occur.
Compare this to 1983 when tank 11 at Milford
Haven was fought in two waves: firstly by applying
foam at a rate of 10400 L/min (2300 imp gpm)
and secondly at 14500 lpm corresponding to an
application rate of 3.0L/m2/mi. 3 canons were
lifted onto the collapsed tank shell to extinguish
the folded shell area.
Since then Williams Fire & Hazard have devel-
oped their Daspit tool, a monitor specially adapted
to fix to the tank wall that allows firefighters to
target a rimseal fire from an above ground
position without risking expensive hydraulic access
appliances nor unnecessary hazard to firefighters.
As Dwight Williams of Williams Fire & Hazard said
during one of their recent incidents:
"The risks here are many � but first and
foremost on everyone's mind is not to sink the
pan. This was a floating roof tank with a pretty
good seal fire on it. You cannot allow that seal fire
to jeopardize the integrity of that roof and sink it
into the product. If that happens you immediately
go from a 2,000 gallon per minute application to
14,000 gallons per minute!"
"We got everything into place very efficiently
and knocked the fire out 20minutes after arriving!
You can't accomplish that without knowledgeable
and helpful teamwork."
The LASTFIRE study indicates a very low proba-
bility of full surface fires on floating roof tanks as a
result of rim seal fires. However, if there is a spill
fire on the roof or an impinging bund fire, the
probability for a full surface increases. Due to the
fact that floating roof tanks are very often large
diameter tanks, they will also create one of the
most challanging situations in a tank farm.
Refineries and fuel storage sites are increasingly
adapting to the needs of high flow monitors and
are investing in the combined infrastructure � moni-
tors, foam stock, high flow hoses and high volume
pumps � designed to deal with fully involved tank
fires. The greater sharing of information on a world-
wide scale through organisations such as JOIFF
(Joint Oil Industry Fire Forum) is leading to a consen-
sus that the armoury to fight these fires includes
both fixed and portable equipment. Where sites are
in close proximity to one another, mutual aid
schemes are being developed so that the infra-
structure costs can be shared. It's not surprising that
this type of specialized resource is beyond the
means of municipal fire brigades when we consider
that they have severe budgetary restrictions and
whose remit is arguably not to finance the resources
for very exceptional industrial hazards.
References
Thanks to Williams Fire & Hazard Control for supplying
information and photographs.
LASTFIRE: The LASTFIRE Project provided an inde-
pendent and comprehensive assessment of fire related
risk in large, open top floating roof storage tanks
resulting in a methodology by which site specific Fire
Hazard Management policies can be developed and
implemented. It therefore represents a major advance
in the knowledge of this risk. Resource Protection
International www.resprotint.co.uk
Joint Oil Industry Fire Forum: www.joiff.com
IFP
50 INTERNATIONAL FIRE PROTECTION
STORAGE TANK FIRE PROTECTION
STORAGE TANKS
Williams Fire & Hazard
Control � Daspit monitor
High back
pressure foam
generator R-PFG
Semi-subsurface
foam injection
device � HSSS
Expander
Foam
sealing
membrane
� SM
Unfolding
hose
Check
valveConnection
Fire Brigade
Base injection/semi-sub surface
base injection

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