Many fire experts often consider the following three factors of critical importance to effective engine company operations:
1. Hose diameter and flow rate
3. Hose loads
Of course, quite a few good points have been made to support such an argument, but some scientific misconceptions can also be found regarding the use of water for fire control in an effective and efficient way. For openers, let’s talk about flow rate concisely.
For one thing, gallons per minute (gpm) matters, and it is outdated and dangerous to use 95- and 125-gpm attack lines on the grounds that:
1. Increasing use of synthetic building materials, such as foams, plastics, vinyl, and volatile coatings, makes fires create higher rates of release.
2. Improved insulation, intending to save the rising cost of energy, significantly seals the fire and increases the heat inside the house or building.
3. Due to more effective fire prevention programs and inexpensive smoke detectors, firefighters can arrive at the fire scene much faster than they could years before.
All this implies that firefighters are getting to hotter, more aggressive fire scenes faster than ever, exposing themselves to possible flashovers and backdrafts.To fight against the beast of fires more effectively, we need better weapons in our arsenals that can provide more water at greater gpm and a faster pacebefore the interior attacks.
In short, it is the gpm that kills the beast, neither the pressure nor the steamas most fire experts claim.
Fire Power vs. Firefighting Power
Undoubtedly heat release rate and desired flow rate are highly related to fire control. Heat release rate is considered the most critical factor.If it does not reach a certain level, say a small fire in a steel garbage can, the fire will not flashover or fully develop within a short time.
But there is a good chance that heat release rate is sufficient to cause flashovers when a small fire involves even a single piece of furniture. This happens only when enough amount of oxygen enables the fire to release chemical potential energy in the fuel.
Therefore, if the doors and windows are closed, the fire inside the house or building may soon use up the remaining oxygen. That means heat release rate will be limited by poor ventilation, and the fire is not likely to develop.
Water is an excellent extinguishing agent in that the conversion of it into steam absorbs 7.5 times more energy than heating up water from 20℃ to 100℃. In other words, how effectively firefighters work on the fireground depends not only on flow rate, though flow rate plays important role in absorbing heat by transforming itself from liquid into gas.
An adequate flow (gpm or lpm) is required to convert water to steam. Energy absorbed during this process will significantly impact fire extinguishment once the steam fails to extinguish the fire.