Fire safety: when evacuation isn’t an option
When fire breaks out in a highly populated building, the first priority is to ensure occupant safety, normally by quick evacuation. But what happens when the whole purpose of that building is to prevent people from being evacuated? That’s one of the dilemmas in designing fire safety for prisons.
It happened in Victoria recently when a fire broke out following a riot caused by an imminent smoking ban, a disturbance echoed in other facilities. The emergency services responded quickly, the fire was brought under control, and nobody was hurt. (Tragically, three female inmates died in 1982 following a fire at HM Prison, Fairlea).
However tragic, compare that with a fire twenty years ago in a prison in the Dominican Republic. Rival gangs in the Higuey facility set fire to bedding, barricaded themselves into their cell block, and began fighting among themselves for control of the prison’s cigarette and narcotics business.
The subsequent fire killed over 134 inmates, one of Latin America’s worst prison fires, in a facility that was dilapidated, poorly designed and vastly overcrowded. The fire wasn’t contained, spreading rapidly from the point of ignition. It hasn’t been the only prison fire in South America. For example, more than 100 inmates died in a 1994 fire at the Sabaneta prison in western Venezuela – again caused by gang fighting in a hopelessly overcrowded facility.
Overcrowding, prisoner unrest, poor fire safety and an inadequate security regime are a repeated refrain in prison fires, often underlining the fact that it’s smoke and toxic fumes that are the main threat to life.
A fire in Honduras is probably the most deadly prison fire in recent history. The 2012 conflagration at the Comayague facility, possibly started deliberately, killed 360 people, including the wives of prisoners on conjugal visits. In terms of lives lost, it was the worst prison fire in a century. It held more than 800 prisoners, had six guards and, reportedly, only one set of keys.
Three aspects to fire safety
Essentially, fire safety in any large building or other facility is down to three things: an alarm system to detect and warn of the danger, a sprinkler system to damp down the fire, and fireproof compartments to contain the fire at source and prevent it spreading.
Taken together, in a prison or any other complex building, those active and passive elements are designed to allow occupants to escape from the building, and provide safe access for the fire and rescue services.
Whatever the building, compartmentation is fundamental to its safety, creating a series of protected fire zones to ensure that the fire is contained. Fire is spread through three methods: convection, conduction and radiation, of which convection is the most dangerous. This is when smoke from the fire becomes trapped by the roof, spreading in all directions to form a deepening layer. Smoke, rather than fire, is often the real danger.
Materials such as metal can absorb heat and transmit it to other rooms by conduction, where it can cause new fires to break out. Radiation transfers heat in the air, until it too sets off secondary fires, spreading the danger away from its original location.
Modern glazing systems can provide complete protection against convection, conduction and radiation – whether as curtain walling, or internal doors or fire screens – for up to two hours, giving more than enough time for a safe evacuation. They are extensively fitted in prisons and other correctional facilities in developed countries.
However, in a fire situation the performance of any glazing system relies on compatibility between the glass and its framing system and that, if one fails, both fail.
In a fire, the sudden venting of oxygen caused by a glazing system failure can have a significant and catastrophic effect on rapid fire growth – at worst, leading to back-draft or flashover, two of the most feared scenarios faced by fire fighters.
We believe that current computational models, primarily to address radiation heat transfer, do not necessarily address the issue of system integration. While both the glass and framing system may have been subject to fire testing, and therefore compliant, only tested compatibility will guarantee absolute system performance when it is most needed.
There are many different areas within prisons – from educational facilities to laundries, from administrative offices to sports and gym facilities. These require little more fire safety features than would be required in any other kind of large and complex building.
The main areas, of course, where special considerations apply are in cell blocks or medical units, where prisoners can be locked into enclosed spaces. At night, staffing levels are also likely to be lower.
However, safely containing fire in a discrete area and having integrated active and passive systems, with trained staff able to respond quickly, can and does provide high levels of fire safety confidence. Compartmentation between cells, both vertically and horizontally, is fundamental to fire containment.
At San Pedro Sula prison this year, three prisoners died in rioting, and where violence, even murder, is not uncommon because it’s a facility that is no longer run by the prison authorities – and which, architecturally, hardly resembles a prison.
The prison today is more of a town with a maze of streets housing cafes and shops – selling everything from iPhones to meat, vegetables to prostitutes. Pigs and chickens roam freely, and the prisoners have built new cells, staircases – and a whole new second floor.
Prison guards do not cross a “linea de la muerte” (line of death) that separates the domains that are controlled by the authorities and the inmates. It makes for an uneasy peace in a facility that was built for some 600 prisoners but which now houses over 2,000.
It is, however, a facility that – like many such institutions in countries that have little or no prison fire safety or adequate security – a very real fire hazard. Perhaps the only certainty is not if, but when, the next fire tragedy will happen.
This article was written by Jane Embury from Wrightstyle Limited, a UK supplier of integrated steel and aluminium glazing systems and exports worldwide. Go to www.wrightstyle.co.uk for more information.