The Point of No Return

By Barry Bouwsema

Advances in technology have allowed a firefighter’s duty gear or turnout gear to withstand hotter and more hostile environments than in years gone by. NFPA 1971 has set high standard for flame resistance and thermal protection. But has this extra protection led to an unsafe fireground condition? Does today’s firefighters understand when they have reached the point of no return?

The point of no return is a measure of how far a firefighter can advance into a hostile environment and still retreat to safety when the situation requires such an action. Several factors, such as individual fitness level and type of personal protective equipment (PPE) worn, will determine where the point of no return exists for any given situation. However, there is one accepted standard measurement of how far a firefighter can advance into a room which appears to be on the brink of flashover, and still allow for the firefighter to successfully retreat to safety. Through research, this standard has been set at five feet. This distance of roughly one body length may be far less than most firefighters might assume. This distance was obtained by evaluating several factors including:

  • Flashover temperatures can reach 1093°C within seconds.
  • At 40°C skin begins to feel hot. Damage to the skin begins at 48°C (first degree burn injury). At 59°C, skin will blister within five seconds. Instantaneous, irreversible skin destruction occurs at 78°C.
  • The average person moves 2.5 feet per second when walking.
  • The thermal protection provided by protective garments is subject to a multitude of variables that will affect its performance in any given situation.

By the time the firefighter can react to a flashover, temperatures will already have risen dramatically. If the firefighter is five feet inside a room that has just flashed over, and has to crawl back to the doorway at 2.5 feet per second, he will be exposed to temperatures up to 1093°C for two seconds in duty gear that may already be reaching the limits of heat stress reduction. At 10 feet, he will be exposed for four seconds � in this situation, the chances are that he won’t make it to the door.

The time necessary for entry, work, and exit from a hostile environment varies for each individual. The factors that will help you to determine your individual point of no return are:

  • Entry point;
  • Physical condition;
  • Size of the individual;
  • Work being performed;
  • Environment where the work is being performed;
  • Amount of air available when entering the environment;
  • Other stresses (e.g., people trapped, difficult access, outside temperatures);
  • Type of protective clothing used; and
  • Training.

To operate safely on the fire ground, firefighters need to understand the concept of point of no return and the warning signs of impending flashover.

Signs of impending flashover include:

  • high heat;
  • thick dark smoke;
  • free-burning fire;
  • fire rollover (a late warning sign).

Take the following measures to prevent flashover:

  • Ventilate – horizontal, vertical, hydraulic, etc.
  • Cool the gases � straight stream pencilling; three quick bursts across the ceiling (larger room, longer bursts).
  • Operate stream into smoke to decrease ambient temperatures.

Technological advances in PPE have allowed firefighters to go further into hostile environments and stay a little longer during firefighting operations. The understanding of modern firefighting techniques will go far protecting your life, and the life of the rookie firefighter on the hoseline behind you. Stay Safe!

Barry Bouwsema is a company officer for Strathcona County Emergency Services, Sherwood Park, Alberta. He has been in the fire service for 20 years, and is a graduate of Athabasca University with a bachelor’s degree in General Studies. Bouswema lectures paramedic students at the Northern Alberta Institute of Technology and teaches firefighters (NFPA 1001) at the Emergency Services Academy.

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