PRINT THIS PAGE (pdf) - FRAME Fire Risk Assessment Method for ...

FRAME - DESCRIPTION
CALCULATING THE POTENTIAL RISKS
The Potential Risks P, P1 and P2 are defined as products of the fire load factor q, the spread
factor i, the venting factor v, the area factor g, the level factor e, and the access factor z.
The first three factors are defined by the fire development, the last three by the fire
compartment environment
The fire load factor q indicates how much can burn
per area unit (m²). It is a measure for the fire duration.
In practice, the "FRAME" calculation sheet provides
tables with reasonable estimates of the values of Qi
(fire load immobile) and Qm ( fire load mobile) based
on building construction types and occupancy classification.
The fire spread factor i indicates how easy a fire can
spread through a building. It corresponds with the
growing phase of the fire. It is calculated from the
average dimension of the content m, the flame
propagation class M, and the destruction temperature T.
"FRAME" gives guidelines how to define these parameters.
The venting factor v indicates the influence of smoke
and heat inside the building. It compares the venting
capacity of the compartment with the sources of smoke
and evaluates the flash-over conditions. It is calculated
with the smoke venting factor k, the ceiling height and
the mobile fire load Qm.
The area factor g indicates the horizontal influence of
the fire. It is linked to the size and the shape of the fire
compartment. It evaluates the fire frequency and the
fire fighting access possibilities. The factor g is
calculated with the values of l, the theoretical length of
the compartment, and of b, the equivalent width, expressed in meter.
The length "l" of a compartment is the longest distance between the centres of two sides of
the compartments’ perimeter. The equivalent width "b" is the quotient of the total area of
the compartment by the theoretical length.
The level factor e indicates the vertical influence of the fire and will be
calculated from the level number E. The main access level has number E =
0. Levels above the access are numbered 1, 2, 3, etc. Levels below the
access level are numbered -1, -2, -3, etc. The formula represents an S-
shaped influence curve.
The access factor z is an aggravating factor for
compartments where outside help can difficultly reach the fire
area. It is calculated by a formula that considers the distance
between the access level and the fire area level, the number
of access directions and the size of the compartment.
1

FRAME - DESCRIPTION
CALCULATING THE ACCEPTANCE LEVELS
The acceptance level reflects the fact that people can live with the threat of fire up to a
certain level, i.e. when the exposure to fire is limited. The exposure is linked to the presence
of ignition sources, to egress conditions for people and to economical data for property and
business.
A higher exposure results in a lower acceptance level. The Acceptance Levels are calculated
with the activation factor a, the evacuation time factor t, the environment factor r and the
dependency factor d. The activation factor a represents the presence of ignition sources, the
environment factor r and the evacuation time factor t evaluate the egress conditions. The
content factor c and the dependency factor d evaluate the economic data.
The activation factor a is defined through a review of possible fire
sources, as a sum of all relevant values, referring to the following types of
fire sources: Main activities, secondary activities, process and room heating
systems, electrical Installations, presence of flammable gases, liquids and
dusts. The "FRAME" calculation sheet provides lists and guidelines.
The evacuation time factor t is calculated by a formula including the dimensions of the
compartment, the number of people, exit units and exit paths, and the mobility factor.
"FRAME" allows also the use of an evacuation time defined by simulation or by evacuation
drills.
The content factor c will evaluate the possibility to replace the
building and its content, and the monetary value. The calculation
allows for various currencies and building cost inflation.
The environment factor r will reflect the running speed of fire, and the dependency factor d
will measure how much a business can be touched by fire.
CALCULATING THE PROTECTION LEVELS
The probability that a beginning fire develops into a catastrophy depends largely on the
available means to fight or to stop the fire growth. Such means are the active and passive
fire protection means that are present. "FRAME" calculates the protection levels with 6
groups of provisions, called W, the water supply factor; N, the normal protection factor; S,
the special protection factor; F, the fire resistance factor; U, the escape factor and Y, the
salvage factor.
The water supply factor W considers the type and capacity of the water
storage and the distribution network for fire fighting. A number of
minimum criteria are given and failure to meet them results in a lower
value for W and a correspondingly higher risk level.
The normal protection factor N considers guard services, manual fire
fighting, time delay of fire brigade intervention, personnel training. A
2

FRAME - DESCRIPTION
number of minimum criteria are given and failure to meet them results in a lower value for N
and a correspondingly higher risk level.
The special Protection factor S considers automatic detection, improved
water supplies, automatic protection, and fire brigade force. The
availability of high performance and highly reliable protection results in
a higher value for S and a correspondingly lower risk level for property and activities.
The fire resistance factor F considers the fire resistance of the
structural elements, outside walls, ceiling or roof and inner walls. The
formula makes a balance of these elements and the available special
protection. A higher level of fire resistance results in a high value for F
and a correspondingly lower level of property risk.
The escape factor U considers every measure that speeds up the
evacuation or slows down the early development of fire. It considers the
effect of special protection in the early stages of fire development and
multiple and protected egress capacity. A higher level of protection
results in a lower level of risk for the occupants.
The salvage factor Y considers protection of critical items and
contingency planning. A higher level of protection results in a lower level
of risk for the activities.
© Erik De Smet
3