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 consequence-based 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-in-place 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 on-site 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.

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