EuroWire November 2015

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Technical article
November 2015 50
This is also valid in respect to fire
safety. For this reason the threat of fire
is estimated differently. This results in
different national or regional approaches
for fire protection. To look deeper into
these approaches it is important to
understand the threats of fire and the
theory of risk.
3 Risk of Fire
3.1 Threats of Fire Events
In occurrence of fire there are different
aspects that people are to be protected
against. In almost all cultures the most
important aspect should be the protection
of life and the avoidance of personal
injuries. Protection of goods against
combustion or secondary damages such
as corrosion are important. This depends
on the value of these goods, which might
be estimated differently in different
cultures. Further economic loss can be
caused by less physical effects of a fire
such as loss of information or downtime of
any infrastructure.
3.1.1 Personal Health
The threats for personal injury by a fire are
much more than suffering burns. Huge
danger in case of fire is generated by
smoke. In dense smoke people may lose
orientation and not find the emergency
exit. In the same way smoke may restrict
the work of rescue teams. Further acid
fumes cause asphyxiation which is the
most often lethal consequence of a fire.
3.1.2 Damage of Goods
In case of fire, damage of goods might
happen by combustion but also by
corrosion effects due to the presence of
acid smoke. Smaller damages by acid
smoke often remain undetected when a
halogenated material burns and a layer of
acid radicals covers some electronics.
When weeks or months later humidity
increases due to weather changes or
else, this film reacts to an acid and causes
failures by corrosion which are not
detected as a long-term consequence of
that fire some time ago.
3.1.3 Economic Loss
The financial damage caused by a fire
might be much higher than the real
value of any devices burnt down. In the
industrial field we know a production
downtime caused by machinery
damage may exceed the cost of the
machinery itself many times over.
Especially in banking and finance the
loss of information is another important
economic threat of a fire event. Thus
additional aspects are to be included
when considering fire protection.
Repairability, data safety and backup
strategies are just a few of them.
3.2 Risk Assessment
Quantitative risk assessment requires
calculations of two components of risk:
the magnitude of the potential loss, and
the probability that the loss will occur.
So risk (R) is determined as a product of
two factors: The probability of any failure
(p) is multiplied by the magnitude of the
potential loss (L) caused by that failure,
further shortly called impact of failure.
R=p*L Equation (1)
This is common knowledge according
to Wikipedia[5] and is used in standard
engineering methods as the well known
failure method and effect analysis (FMEA)
[3] as well as in insurance risk assessment
procedures. Insurance companies use
the risk calculation according to Equation
(1) in risk assessment which is basic to
determine insurance premiums. Here both
factors – probability and impact of failure-
are taken into account, too.
Equation (1) indicates that it is worth
taking both factors into account. In many
realistic cases both factors of risk depend
on each other. To name an example taken
from this fire protection topic, the use
of halogenated materials reduces the
probability of failure but increases the
possible impact on personal health by
asphyxiation or something else.
Experience from FMEA practice reveals
the advantage to keep both factors on a
similar low level. If both factors may vary
in a range from 1 to 10, the risk varies
from 1 to 100. If the probability is reduced
down to 4 and the impact down to 5, a risk
level of 20 as a product of the factors 4*5
is achieved. If the impact remains on its
high level of 10, the probability must be
reduced down to 2 to achieve the same
risk level. Keeping in mind the Pareto
principle, it will be clear that the effort to
achieve this extremely low level of one
factor will exceed the effort to keep both
factors on a medium level.
The advantage to distribute the efforts of
risk reduction to both factors (avoidance
and impact reduction) is shown in Figure 2.
The dashed line shows the risk depending
on reduction efforts if all efforts are
invested into threat avoidance.
The continuous line shows the risk if
the reduction efforts are distributed to
both avoidance and impact reduction
in the same quantity. Some simplifying
assumptions are done in this approach to
show the basic principle easily. It can be
clearly seen that just in the medium part
of the range, the distribution of efforts to
both factors brings clear advantages.
▲ ▲ Figure 1: Cultural relativity for three selected nationalities according to Hofstede [1]
▲ ▲ Figure 2: Remaining risk versus total effort for reduction efforts on one factor or both factors
Power distance
Individualism
Uncertainty
avoidance
Masculinity
Long-term orientation
Germany
Japan
USA
Risk vs Effort
Total Effort
Remaining Risk
Risk (2 factors)
Risk (1 factor)