Picture in courtesy of Lyndon Dennis.

Going inside – strategies to eliminate risk during interior firefighting operations

Published:  14 May, 2012

Paul Grimwood highlights the risk factors that impact on survivability during interior firefighting operations. When firefighters are deployed to the interior of a fire involved building for fire attack, search and rescue operations or as support to crews working ahead or above them, there are several risk critical factors that may impact upon their ability to survive such a hostile environment

This article explores these risk critical factors from varying perspectives in order to represent the different approaches made by firefighters in countries, cities and towns where construction, equipment, staffing and resources may present stark contrasts that will impact upon the tactics employed. It follows that this article is for guidance only.

Firstly though, there are a few key objectives that are generic to virtually every building fire and these are:

  • Pre-plan and familiarise with risk, ensuring firefighters visit the most serious risks in your area. These may include large volume structures and warehouses; areas with high fire loads; buildings with extensive basements, vacant or derelict buildings and tall multi-storey buildings.
  • Where firefighters are deployed to the interior they must work in teams and not as individuals. They should take every opportunity to contain, surround or “cut off” the fire. This might mean simple actions such as closing doors to slow fire spread, or siting hose-lines at key intersections such as stair landings, to contain the fire or protect points of egress, particularly where firefighters are deployed to upper levels.
  • Control the building’s openings to your advantage. In other words, don’t ventilate without a directive or a clear purpose and maintain a closed structure as long as possible, until firefighters are deployed with charged hose-lines. Getting water on the fire before a fast developing well-ventilated fire surpasses the available flow-rate is the key objective.
  • Be situation aware of what the fire or smoke layer is doing in the overhead or above a suspended ceiling, particularly where ceilings are higher than three metres. Failure to do this may allow fire to travel overhead hidden in the smoke, before suddenly dropping down behind and trapping you.

Going inside and staying there.

Make sure you get a good look at the building from the exterior prior to deployment. What signs are there of fire and at what level is the fire development? There may be key indicators such as cracked or blackened windows indicating under-ventilated conditions. There may be smoke emanating from the eaves indicating excessive fire pressures in the building or even a fire in the roof space. Don’t always assume that smoke issuing from a window suggests the fire is located at that level! At one house fire, firefighters deployed directly to the upper floor based on heavy smoke issuing from a bedroom window at that level, whereas the fire itself was located on the ground floor to the rear of the structure! They became trapped and were forced to jump from upper windows with serious injuries.

Some key points and considerations when creating vent openings:

  • Hold off making vent openings until charged hose-lines are ready to deploy
  • Vent only with a directive from authority (may exist in SOP)
  • What is the primary purpose (objective) of the vent opening? (Do I NEED to make this opening)?  What role will this opening play?
  • Optimise venting by creating openings on the opposite side of the fire from the hose-line
  • What direction is the wind and what likely influence will it have on the opening?
  • Where the fire is grossly under-ventilated, give consideration to controlled venting actions at strategic points, prior to any interior deployments taking place.

Rapid fire development.

Large Volume Structures  

(LVS)Compartment fires on a growth curve will generally get worse following fire service arrival before they get better! In most situations firefighters will create an opening/s at the point of entry and this may well feed vital air to the fire for some minutes prior to water hitting the fire. A heavy dark smoke layer leaving the structure with some increasing speed may serve as a warning sign of dangerous under-ventilated conditions. In this situation it is critical that firefighters are not deployed without a fire attack hose-line or at least in unison with a hose-line crew/s operating in support and protecting egress routes. Sudden window failures, unplanned or mistimed venting actions or exterior wind conditions can have a dramatic effect on fire spread. Therefore, situational awareness of the risks must be a pre-determined consideration. This point cannot be over emphasised.

There have been several recent tragedies where firefighters have been deployed offensively to the interior of Large Volume Structure (LVS) fires in the UK, the USA and several European countries. These fires are typical of warehouse or retail type units of open plan for space with ceilings above six metres. Over the past decade such fires have taken the lives of multiple firefighters.

It is important to establish operational guidance or training documents specifically for these structures, as rapid fire spread may be hidden in the overhead due to high ceilings and dangerous fire phenomena may occur without sufficient warning in time for escape. The following points are critical to firefighter safety in such buildings:

  • Due to the high ceilings masking fire development in LVS, firefighters must be trained and encouraged to develop a much greater level of situation awareness in these situations.
  • Deployment to the interior should only be undertaken for offensive operations whilst the smoke layer remains high.
  • Match the water flow-rate with the potential fire load and deploy main hose-lines into large compartments at all times.
  • Make sure there is good communications between all deployed crews and a control point outside.
  • Any deep penetration into the building should be avoided where fire is clearly taking a hold.
  • Use exterior access points to deploy far reaching hose-streams in order to suppress a known growing fire.

If a smoke layer above is approaching within three metres of head height if a smoke control system exists, or within five to six metres without smoke control or if there are noises at the ceiling such as banging, or popping steel bolts, then firefighters should immediately evacuate the building.

Fire loads can be excessively high and fire growth dangerously fast but temperatures at head height may appear normal to firefighters because of the high ceilings.

Where LVS are protected by sprinklers, an alternative approach is needed. It may be that sprinkler operation has controlled but not extinguished the fire, driving some smoke to the floor. In this situation the fire compartment must be assessed internally to see if the sprinklers are maintaining the fire under control. If so, firefighters should attempt to extinguish any remaining or shielded fire, keeping in mind the length of time the sprinklers may be supplied by storage water.

At one fire in a very smoky warehouse where the smoke layer reached the floor the fire could not be located. Despite there being no heat at lower levels, firefighters were evacuated and a series of large PPV fans were used to clear smoke from the building. The fire was then located as a smouldering fire in pipe lagging, sufficient to smoke-log the warehouse over several hours before the fire service were called.

Safety hose-lines

Whenever firefighters are deployed to the interior, their route of egress should be protected at all times. This means a support (safety) hose-line might be located between any firefighters and the fire, particularly if they are working above the fire. If a hose-line crew are extinguishing fire up a stairway, a safety line/s should be deployed behind them to ensure any fire doesn’t reignite and trap them above.

In areas where twists and turns are likely to be encountered in the hose-run, or where penetration is more than one hose-length into a building, a hose support team should also be deployed solely for the purpose of assisting the advance of the hose-line. This is important, particularly where larger diameter lines are deployed. To advance a 51mm (two-inch) hose-line effectively and speedily into a fire building may require at least four firefighters in total.

Fire stream applications and water flow-rate.

Modern fire loads coupled with energy efficient buildings suggest that firefighters must be deployed with adequate amounts of water in order to match the potential involved fire load. In some cases the increasing fire load involvement may exceed or surpass the suppressive capacity of the hose-line deployment/s and in these situations the safety of firefighters is of prime concern.

Taking into account that a “safety” hose-line should be laid in support at the earliest opportunity; where a compartment fire’s energy release (HRR) exceeds 20MW then a secondary hose-line is urgently needed to assist the fire attack. Failing this, firefighters should be withdrawn and an external fire attack implemented.

Tactical rule-of-thumb guidance - a >500 litres/min (132 gall (US)/min) flow-rate is needed for each 100 sq.metres (appx 1000 sq.feet) of fire involvement at peak steady state burning.

Key point – ensure you have flow tested all of your nozzle and line configurations and not relied on manufacturers data! The 500 litres/min nozzle may only be flowing 250 litres/min in reality if incorrectly configured or pumped!

The belief that “small amounts” of water from hand-held nozzles can suppress large amounts of fire if applied in the finely divided droplets  of a fog pattern only holds true up to an approximate fire size of

Critical matters.

Establish key control measures at the very earliest opportunity in support of interior crews, such as safety (support) hose-lines and Rapid Intervention Teams (RIT) or Emergency Crews ready outside the structure.

Ensure effective command and control is established from the outset and where crews are deployed internally, the incident commander remains at a location best suited to overseeing how the fire indicators, building and overall firefighting operations are progressing.

Pre-determine how lightweight construction or particular building elements such as roof trusses or engineered timber floor joists may affect safe operating time-frames for your firefighters.

Establish pre-determined safe operating practices and achievable task objectives where staffing or resources are limited.

Encourage a situation and risk aware culture and establish safe working practices based on national experiences of fire-fighting in/around vacant or abandoned structures.

Final message to firefighters –

“Too much safety makes Johnny a poor leader and a terrible rescuer,” said FDNYs Lt. McCormack in his now famous 2009 FDIC speech. He went on to say that firefighters are being taught to place their own safety above all else, saying that the lives of civilians could be put at risk because of this. Acknowledging that the general intention of his message is welcomed by the majority;

Some thought provoking definitions ….

Aggressive: Assertive, bold, and energetic, forceful, determined, confident, marked by driving forceful energy or initiative, marked by combative readiness, assured, direct, dominant…

Measured: Calculated; deliberate, careful; restrained, thoughtful, considered, confident, alternatives, reasoned actions, in control, self-assured, calm…

Which is the optimum definition that would define a highly skilled, knowledgeable and dedicated firefighter in 2012? Where does the rightful balance or combination lay?

Where do YOU fit in? 

Please, let us know your thoughts on this article, email the editor

 Paul Grimwood is one the world’s most renowned firefighting experts. He is the author of several books, including: Eurofirefighter (www.euro-firefighter.com). He is also the Principal Fire Safety Engineer for Kent Fire and Rescue Service.

 

  • Operation Florian

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