MineARC Systems
Depending on the nature of a toxic or flammable gas hazard, the time in which on-site personnel may need to shelter can vary from a matter of minutes to several hours. The function of shelter-in-place locations is necessary to provide a secure shelter where personnel can safely take cover.
It is generally recognized that "nonbuilt- for-purpose" buildings do not meet acceptable leak tightness for long-duration releases greater than 60 minutes. With ventilation shut down, a typical building can have up to five air changes per hour or higher depending on wind speed. Door operation as people enter can potentially bring additional contaminants from outside the shelter. As contaminated air infiltrates a building, the level of protection provided to the occupants diminishes with time.
Once an external gas release has been contained, toxic exposure inside a building will continue. The concentration levels inside a building may actually exceed the concentration outside, due to the building's tendency to retain airborne contaminates once they have infiltrated the shelter. This can have the effect of doubling the necessary shelter-in-place duration requirement. All of these factors need to be considered within a facility siting study (FSS) to assess potential explosion risks and determine the vulnerability of occupants sheltering within a building prone to leaks.
A safer and more economical alternative is to seal smaller existing rooms within a larger building. There are cost-effective means to create a "very tight" room within a building by using specifically designed components such as sealing doors and vestibules. A properly constructed, unventilated sealed room can potentially have a leak rate of less than 0.1 air changes per hour. These tightly sealed rooms, however, cannot be occupied for long periods without the risk of occupants producing a high level of carbon dioxide and dangerously reducing oxygen levels. Carbon dioxide is an asphyxiate gas that can reduce or displace the normal oxygen concentration in breathing air and causes serious injury, leading to a loss of consciousness and eventually death. Removal of harmful gases is a vital necessity for entrapment situations.
The MineARC AirGEN Scrubbing System "scrubs" the air of carbon dioxide, effectively cleaning the air of harmful gasses so occupants can rebreathe it. The AirGEN is simple to operate with only a single switch and operates from its own internal battery supply, independent of external power.
It is recommended a supplementary oxygen supply be included in the form of compressed oxygen or a sodium chlorate candle. Oxygen delivery can be automated based on established low and high limits for oxygen and will keep the sealed room under positive pressure. Optional positive-pressure maintenance systems are available for facilities with a higher leak rate or that are just looking for additional protection. MineARC understands every company has different requirements for each particular development, therefore tailoring each project based on client needs. MineARC is able to provide clients with 24- hour global support on custom design projects, commissioning and servicing.
MineARC engineers, manufactures and supplies refuge chambers, ancillary mining and industrial equipment to operations in over 40 countries.
For more information, visit www.minearc.com or call (214) 337-5100.
