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Trainer’s Corner: Venting, a human and fire behaviour perspective

November 4, 2021 
By Ed Brouwer

A backdraft is the biggest danger of all and the risk must be eliminated before moving on to other fire ground priorities. Photo Credit: © lukszczepanski/adobe STOCK

This issue’s topic is ‘venting’. Now, don’t set this aside because you think you know this subject already.  I hope to get you to see the need to understand this topic both from a fire behaviour and a human behaviour perspective.

In a nutshell, ventilation is the planned, coordinated and systematic removal of pressure, heat, gases and smoke.  This can occur as a natural result during a fire, or it can be produced by mechanical means such as from positive pressure (PPV fans) or negative pressure (ejectors/extractors). When other types of ventilation are unavailable, hydraulic ventilation is a viable option.  

Simply stated, ventilation is the movement of air from high pressure to lower pressure.

There are three reasons we perform ventilation: life safety, incident stabilization and property conservation. Let’s look at why. 

  • Life safety: Improve the chances for fire victim survival, improve interior visibility, and improve firefighter efficiency.
  • Incident stabilization: Reduce interior heat levels, decrease rate of fire spread and reduce potential for extreme fire behaviour.
  • Property conservation: Reduce smoke damage. 

There are two types of ventilation, horizontal and vertical.  These can both be extremely dangerous if not performed properly. To be successful in venting, there are several subjects your members will need to understand, including fire behaviour, fire streams, and ground ladders, just to name a few.

A key and often overlooked point is that you need to know where the seat of the fire is before making an opening in the fire compartment.    

On a personal note, it concerns me that paid-on-call/volunteer departments practice ‘opening the roof’.  Mechanical vertical ventilation is a dangerous operation. With the low number of structure fires per year that would require cutting holes in the roof (one or two per decade), why are we putting firefighters at such an extreme risk? In my 31 years as a firefighter, I never had to cut a hole in the roof to ventilate a burning structure.  

Don’t take my word for it, there are many “close call” videos to prove my point at how dangerous this operation is.  And should you want to see what happens when ventilation goes wrong, just type in “ventilation goes wrong” in your search bar.  

Let’s also talk a little about backdrafts, or smoke explosions. These may happen if the fire becomes severely limited in oxygen. The goal of venting in those cases is to remove as much heat and smoke from the structure as possible before introducing any new oxygen.

If you think it is worth the risk to make a rescue attempt, please consider, in a fire where the conditions are right for a backdraft to occur, there is absolutely no chance of finding anyone alive in the building. 

The biggest danger, by far, is that of a backdraft and so the risk must be eliminated before firefighters can move on to other fire ground priorities. Consider as well that the main building may be ventilated, but there could be individual compartments in that building primed for a backdraft or smoke explosion. As a sidenote, a vehicle fire may also end up being a backdraft situation.  

In a backdraft, a fire burning in a confined area consumes all the oxygen, and flames are no longer visible. As temperatures increase, the gases expand, and pressure builds. Any opening that allows oxygen to enter the space will result in the explosion of the pressurized gases.   

When our kids were very young and we asked them about where they’d like to go for dinner, they usually said, “Anywhere but that ABC place.”  When asked why, the answer was always, “Dad, ABC — Already Been Chewed — eww!” Training is kind of like that, instructors often do all the work (chewing) for the members. Why not divide into small groups and just ask questions? I have had great success in dividing our firefighters into three or four groups and assigning a different topic to each group, asking them to put together a 10-minute lesson on their topic. Try questions like: What is positive ventilation? What are the signs of flashover? Your members may very well surprise you.  

Fire behaviour can also help us understand human behaviour. I’m sure you see the importance of proper venting as it pertains to fire behavior, but have you ever considered the role and importance of venting when it pertains to human behaviour?  We are witnessing unprecedented polarization in our country, resulting in extreme divisions, angry public demonstrations, and violent acts of racism. This pandemic has changed our country. It feels like we are on the verge of civil unrest. 

I believe that much of the negative reaction is due to the fact that people feel like they have no voice. Could it be we have thousands of people walking in “pre-backdraft” mind sets? Like a fire starving for oxygen, people are desperate to be heard. Many are fed up with hearing about COVID. Social media and the daily news are overwhelmingly consumed with the pandemic, vaccines, mandates, passports, etc. The danger, of course, is when people are that primed to explode, it only takes a wrong look, a misunderstood word, or going the wrong way down an aisle in Wal-Mart to detonate. (My cart was once rammed by an irate elderly man because I was going the wrong way).  

 We have no control over the whole nation, but you have some control of your firehouse. Please be sensitive to each of your members. Each one is important; be sure they know that. Each member’s voice should be valued whether they agree with you or not. Safe venting can save your fire department from exploding or imploding.  Many first responders are near their breaking point. Make every effort to give them opportunities to rehab mentally.  Provide opportunities for your members to ask questions or express their concerns and fears. And, NO, you do not have to have an answer. Just provide a safe venting opportunity. Positive ventilation versus negative ventilation.   

Another key point is that you don’t need to “vent” the whole department at once. Sometimes safe venting can be done one to one over a coffee.  Do not over complicate it. 

I’m not trying to lay more on you, but we are talking trainer to trainer in this article so let me first say to you: Please look after yourself and your family.  Secondly, it is no secret, but sometimes your role as a trainer is more like a mediator between the firefighters on the floor and those in the administrative roles. Please do not go it alone. Get some help from outside your department. I have been in that position more than once and hated every minute of it. In one situation I was way too inexperienced and too slow (or prideful) at getting outside help.  There were clear divisions between members, and because voices were silenced, polarization grew until a wrong word caused that department to implode. It took years for those wounds to heal. When a firehouse implodes, it doesn’t happen overnight. Those fires have been smoldering for a long time. Thankfully the other situation ended positively, for we were able to “vent” safely and the department was the better for it.     

Until next time remember to train like lives depend on it because they certainly do.  

Ed Brouwer is the chief instructor for Canwest Fire in Osoyoos, B.C., retired deputy chief training officer for Greenwood Fire and Rescue, a fire warden, wildland urban interface fire-suppression instructor and ordained disaster-response chaplain. Contact 

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