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Foam follows function: T
his is the third article in a series featured by Fire
Chief
, which started with a description of the prob-
lems encountered when fire and
extinguishment trials with new agents
are conducted, when the results are to
stand up against scientific as well as real-
life firefighting challenges. (See When
did you fight your last crib fire? March
1997, available at <www.firechief.com>.)
A year later, we were able to publish
the first part of results that we obtained
from trials extinguished using
CAFS.
(See CAFS goes to Germany, August
1998, available at <www.firechief
.com>.) In
1997 and 1998, we ran 21
more fully instrumented room-and-
contents fire trials, as well as eight fire
trials with paper-recycling containers.
The Tremonia trials
The first scenario, in which
21 fire trials
were performed, was a room-and-con-
tents fire. Inside a tunnel of the former
research mining field Tremonia of
Deutsche Montantechnik, in Dort-
mund, we set up a burn room. The tun-
nel was approximately
3 meters wide
and
3 meters high.
Inside this tunnel we created a
room
5 meters deep by erecting two
walls from magnesia-silicate board on
2-
inch steel C-frames. This drywall con-
struction had a rated fire resistance of
90 minutes. One wall had a window, the
other a door opening. On the door
side of the room, two little hatches near
the floor were opened to allow for video
surveillance of the room and for
improved ventilation, since firefighting was to be started
after flashover.
Twenty-four thermocouples were installed at various
heights and positions evenly inside the room, as shown in
Figure
1. There were also nine gas-sampling probes, three
each for oxygen,
CO and CO
2
. Data was obtained and stored
110
FIRE CHIEF / August 1999
Foam follows
function:
The results of comprehensive tests in
Germany cut through the hype about the
effectiveness of Class A foam and other
firefighting additives versus plain water.
By Holger de Vries, Fire Protection Engineer
University of Wuppertal, Germany
The Tremonia and
Wattenscheid trials
Ignition
Bed
Shelves
Table
Armchair
Armchair
Wooden chair
Wooden/
steel chairs
Height
2.5 m
1.5 m
0.5 m
24 thermocouples
in the cross-sections
of the grid
Entry
Exhaust
Set-up of the Tremonia trials
Figure
1
T H E G L O B A L F I R E S E R V I C E
An attack team advances into the fully involved burn room in
the Tremonia trials.
Daniel Guischard 112
FIRE CHIEF / August 1999
every second. The facilitys water pipe was supervised electron-
ically so that the water flow used for fire attack was also record-
ed every second.
Three hundred eight kilograms (
680 lbs.) of solid fuel
were set up as furniture inside the burn room. (See Table
1.)
The energy released inside the burn
room was predominantly from solid
Class A fuels; that released by the
2 liters
of heptane used to ignite were negligi-
ble. Given a pre-burn time of
15 min-
utes, the overall energy released by that
fireload was between
738 and 1,029kwh
(or
2.5 million BTUs to 3.5 million BTUs),
with an energy release rate of between
2.9 and 4.1mw (megawatts), or 2,750
BTUs/second to 3,890 BTUs/second.
In Germany, there are no regula-
tions governing the performance of live
fire trials. Given the testing tunnels
structural integrity, we followed
NFPA
1403, Live Fire Training Evolutions
(
1997), and the German Standing
Orders for Firefighter Occupational
Safety and Health for the given scenar-
ios (safety officer, backup team, backup
water supply, communications,
EMS and
so forth).
We needed to choose an appropri-
ate nozzle and flow for the attack line, so
as to neither flood the burn room nor
have no impact. According to the Iowa
rate-of-flow formula, a room this size
required a minimum flow rate of
59lpm
(
16gpm), while according to German
formulas between
67.5 and 150lpm
(
1840gpm) were required. We thus
chose to use a Task Force Tips Quadra-
Fog
40gpm (adjustable-flow) nozzle on
a
1-inch attack line. (Pressure loss inside
the
50-foot line was negligible.) The
backup team was provided with a
2-inch
line and an Elkhart Brass SM
10 F noz-
zle, providing a
380lpm (100gpm) flow
in case of an emergency intervention.
Table
2 gives an overview of the tri-
als. During the first three trials, the posi-
tion of the fire load was altered to achieve a fast fire spread to a
fully involved room. Furthermore, there were slight variations
of the beginning of the intervention during these trials. For
trial W-
20, the participating Berlin firefighters wanted a triple
fire load and
60 minutes of pre-burn to evaluate their new
turnout gear, so this trial wont be regarded any further.
We used three extinguishing agents (water, Class A foam
at
0.5% and a sodium polyacrylic additive at 3%) and two dif-
ferent attack methods (direct and indirect).
For the induction of
0.5% Silv-ex G (the German version
of Ansuls Silv-ex), we used Robwens Flow-Mix
500 bladder
tank proportioner and a FireDos
1000 water motor propor-
tioner. The FireDos proportioner, made by MSR Dosiertech-
nik (Am Heiligenstock
2, D-61200 Woelfersheim, Germany), is
basically a fine piece of equipment, but it had problems
responding to the low flows in this scenario, so it was replaced
by the Flow-Mix in the following trials.
The idea of the sodium polyacrylic additive is to thicken
the water, thus preventing it from running off the fuel before it
can properly cool it down. For the induction of the
SPA, repre-
sentatives of the manufacturer were on site and provided an
in-line eductor. However, the
SPA repeatedly clogged that
eductor, our own bypass eductor, the hoselines and the
TFT
nozzle, so that setup and flushing required a major effort. Fur-
thermore, the
SPA created a very slippery layer on the burn
room floor, so that the safety of the participating firefighters
was at risk.
Table 2: Overview of the Tremonia trials
Start of
End of
intervention
intervention
Extinguishing
after ignition
after ignition
Trial name and abbreviation
method
[min:100ths]
[min:100ths]
Water 1 (W-1)
Indirect
24:23
30:90
Water 2 (W-2)
Indirect
16:04
24:20
Water 3 (W-3)
Indirect
14:75
28:77
Water 4 (W-4)
Indirect
15:02
24:50
Water 5 (W-5)
Indirect
16:25
24:28
Water 6 (W-6)
Indirect
18:84
29:85
Water 7 (W-7)
Indirect
15:60
26:81
Water 8 (W-8)
Indirect
17:13
34:03
Water 9 (W-9)
Indirect
14:73
23:96
Silv-ex 10 FireDos (S-10)
Indirect
15:10
20:29
Silv-ex 11 FireDos (S-11)
Indirect
15:31
25:48
Gel 12 Z1 in-line eductor (G-12)
Indirect
20:20
33:88
Gel 13 Z2R by-pass eductor (G-13)
Indirect
15:44
24:89
Silv-ex 14 Flow-Mix (S-14)
1
Indirect
15:23
23:21
Water 15 (W-15)
B
Direct
15:32
21:30
Water 16 (W-16)
B
Direct
15:52
27:75
Silv-ex 17 Flow-Mix (S-17)
2
Indirect
15:50
27:84
Water 18 (W-18)
B, 2
Direct
15:52
23:73
Water 19 (W-19)
B
Direct
15:85
21:13
Water 20 (W-20)
B, 3
Direct
61:15
84:40
Silv-ex 21 Flow-Mix (S-21)
4
Indirect
15:40
26:34
B: Attack team provided by Berlin Fire Department.
1: Hoseline burst, attack somewhat impaired but successful.
2: Trials
17 and 18 run on one day with different attack teams.
3: Triple fire load,
60 minutes of pre-burn (not used for comparison).
4: Attack team changed from Flameco
10gpm foam nozzle back to TFT nozzle during attack.
Silv-ex was Silv-ex G Class A foam at
0.5% induction rate
Gel was sodium polyacrylic additive at
3% induction rate.
Direct attack involved predominant use of a full stream directed at the fuel.
Indirect attack involved use of fog stream to cool hot gas layers under the burn room ceiling, then
further advance using fog and full stream on the fuel
Times are given in minutes and decimal seconds.
Table 1: Fire load inside the Tremonia burn room
Mass of
Total
Fire load
single item (kg) mass (kg)
Bed consisting of steel frame with:
One mattress
17.5
17.5
Two wood pallets
16
32
Shelf consisting of:
10 wood pallets
16
160
Wooden table on steel frame
8.5
8.5
Two armchairs consisting of:
Two automotive seats
15
30
Two pallets
16
32
Wooden chair
6
6
Two wooden chairs with steel frames
5.5
11
Shredded newspapers
4.5
9
Cotton-polyester fabric
2
2
(to simulate tablecloth, bedspread, etc.)
Heptane (in steel tray under shelf)
2
2
Total mass of combustible materials
310kg August 1999 / FIRE CHIEF
113
As shown in Table
2 (below left), in five
trials, the Berlin Fire Department provided
the attack team. These firefighters preferred
direct attack, while the Wuppertal entry team
advanced using indirect and combination
attack.
The fires were ignited by
2 liters of hep-
tane poured into a steel tray under the shelf.
The standard pre-burn time was
15 minutes,
then the attack team opened the burn room
door, entered and began firefighting. The
attack team was always covered by a backup
team only a few feet away.
The reports of the backup teams gave
valuable information on the situation inside
the burn room in comparison to the attack
method: Indirect attack, as used by the Wup-
pertal teams, usually led to a collapse of the
flames under the rooms ceiling after applying
only a few bursts of fog spray upright into the