African Petrochemicals Edition_16.2

MINEARC EDITORIAL: CONVERTING SHELTER-IN-PLACE
LOCATIONS TO ZERO VULNERABILITY SAFE HAVENS
AirBANK Positive Pressure System with breathable air cylinders.
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While it is not uncommon to find
shelter-in-place or safe haven locations
designated across chemical facilities,
what varies is the level of protection
offered at these sites. Functionality
can range from merely a muster point
(shelter-in-place) to a positively
pressurized room (safe haven). Either
way, when determining if a room is
acceptable for the job, the industry
generally applies a vulnerability factor;
in other words, the probability of a
fatality being less than one percent.
Emergency shelter-in-place (SIP) should
form an integral part of any chemical
plant’s broader emergency response plan.
Explosions, fires, and the release of smoke
or other toxic gases are some of the types of
incidents that can occur despite high levels
of planning and safety precautions.
Numerous government agencies and other
organisations recommend SIP to protect
personnel from harm in the event of a
chemical release. Any building may be used
as a temporary measure to reduce health
risk from exposure to the toxic materials
by simply closing windows and doors
and turning off ventilation fans and air
conditioning/heating systems.
Three factors govern the effectiveness of a
SIP location:
• the tightness of the building or leakage
rate
• the concentration of the toxic gas, and
• the release duration.
The tightness of the building is primarily
based on building construction; however,
temperature differential and wind speed can
also play a factor.
Identification of the maximum toxic
concentration occurs during a Facility Siting
Study (FSS). FSS’s are a hazard analysis
that defines Maximum Credible Event
(MCE) scenarios using a consequencebased
approach to produce a quantitative
risk assessment. Determining potential
consequences is a necessary step in the
process of developing a comprehensive
safety plan.
The FSS also determines the expected release
duration based on stored inventories of toxic
materials. The higher the toxic concentration
and longer the release duration, the less
effective sheltering-in-place becomes.
While occupants may feel safe sheltering-inplace
from the external toxic hazard, typical
buildings have high leakage rates. A typical
wood framed constructed building can
have 3-5 air changes per hour, rendering it
ineffective against most chemical releases.
Additionally, sealing to an acceptable
airtightness can be time consuming and
expensive and even with professional air
sealing it is very difficult to seal existing
structures to an acceptable tightness.
There are considerations for effectively
sealing existing infrastructure and ensuring
positive pressure to ensure contaminants
do not infiltrate safe haven locations along.
Critical elements of life support that are
of primary importance to human survival
must also be considering when converting a
shelter to a safe haven; including:
• Positive pressure
• Breathable air supply
• Supplemental oxygen
• Removal of accumulated carbon dioxide
• Cooling and dehumidifying
MineARC Systems have converted SIP spaces
to positive pressure safe havens with the
installation of life support systems across
many chemical sites globally. The MineARC
AirBANK Positive Pressure System provides
rapid pressurization, which is activated
and maintained using the AirBANK Control
via a simple human-machine interface
(HMI) touch screen. MineARC’s integrated
Aura-FX Gas Monitor ensures breathable air
automatically remains within acceptable
limits. Additionally, supplementary oxygen
and carbon dioxide scrubbing systems can
be installed as required.
Reducing the risk of harm to personnel is a
priority for emergency response planning.
While the likelihood of an Maximum Credible
Event occurring may be low, the risk to onsite
personnel in the event of an incident
is high. Converting shelter-in-place (SIP)
locations to zero vulnerability safe havens
improves emergency response.
For more information about the conversion
of a shelter-in-place to a safe haven on
your site, please contact a local MineARC
representative at info@minearc.co.za.