CONTROL THE AIR TO CONTROL THE FIRE!

When fires burn, the thick dense smoke often contains toxic and flammable gases that cause the rapid spread of fire. These increase thermal phenomena such as "flashover," "smoke explosion" and "backdraft". These are potentially very dangerous for firefighters. The smoke generated by a fire is at the center of the mechanism of thermal phenomena. It is essential to understand how it is formed and know its nature in order to learn how to control it.

Therefore, operational ventilation has today become an important phase of firefighting operations. The recent publications of the “Operational Doctrine Guide - Interventions on structural fires (in 2018)” (Guide de Doctrine Opérationnelle – Interventions sur les incendies de structures) and of the “Operational Technical Guide - Operational Ventilation” (in 2019) (Guide Techniques Opérationnelles - Ventilation Opérationnelle), have laid operational foundations for all French rescue teams. The aim is to give everyone the choice of firefighting tools and methods, while providing common rules. This new operational approach leaves the necessary scope for each fire and rescue service to choose its equipment and gradually deploy the appropriate techniques.

Operational ventilation offers many advantages to a rescue operations commander who is usually faced with situations in which it is necessary to react quickly.

BUT WHAT IS OPERATIONAL VENTILATION
AND WHAT ARE VALUES?

In general, this term includes all actions aimed at controlling gas flows (smoke loaded with toxic gases, vapors and particles), whether in the air supply, as well as in the management of aeraulic flows (smoke evacuation) naturally (with the wind, for example) or forced (using a PPV fan).

In other words, Positive Pressure Ventilation (PPV) is all the actions taken by the firefighters which help to control the gas flow in the structure affected by the fire; therefore ventilation, whether it concerns its air supply or the discharge of combustion gases such as:

• Anti-ventilation;
• Positive Pressure Ventilation (PPV);
• Natural or forced smoke extraction;
• Protection of a volume by overpressure

There are three major phases in the operations involving positive pressure ventilation:

• Ventilate to protect,
• Ventilate to remove smoke,
• Ventilate to attack.

These phases were determined as a graduated response, facing different types of disasters and adaptable to specific building structures, by their form or their operation.
 

FIRST TACTICAL:
VENTILATE TO PROTECT OR DEFENSIVE VENTILATION
 

The first of these operational tactics is named "ventilate to protect".

1/What does this operational ventilation technique consist of?
Its aim is to pressurize volumes in order to avoid smokes to reaching them.

2/What is the advantage of this fire ventilation technique?
This tactic will limit the risk of the fire spreading by smoke and will also prevent contamination of premises not initially affected by the fire.

3/How to implement this operational ventilation tactic?
Very easy and quick to implement, this ventilation tactic does not require too powerful PPV fan when the volume to be protected is small; a portable battery powered fan such as the BATFAN battery fan, very simple and quick to set up, will often be sufficient for the most common volumes.

In this case, it is recommended to use an electric firefighting fan in order to avoid the production of exhaust gas in the volume to ventilate (a gas-powered ventilator equipped with a catalytic converter associated with an exhaust extension will also be a good way to reduce the risk of exhaust smokes).
 

For larger commercial or industrial volumes, there are Large Flow Fans also called LFV (such as the EASY 2000 Large Flow Ventilator and EASY 4000 Large Flow Fan) specially designed to ventilate large structures such as tunnels, airports, warehouses cooling, industrial complexes, high-rise buildings, etc ...

This ventilation tactic (aimed at protecting volumes unaffected by fire smoke) also allows operational ventilation to be approached safely and with few constraints. As the air flow sent by the fire fan does not touch the heart of the fire, there is no fear of adverse effects.

SPECIAL CASE: VENTILATION IN ATEX ENVIRONMENT

It is sometimes necessary to ventilate structures containing explosive and flammable atmospheres requiring specific precautions. With its range of ATEX fans, LEADER has made the choice of safety. The design of the ATEX fan has been the subject of extensive technical studies, in order to ensure compliance with the ATEX standards in force.
The ATEX LEADER fan can be used for various mobile ventilation applications in industry (for the evacuation of harmful smokes, explosive or toxic gases, for cooling an overheating machine, for pressurizing a volume in order to protect it thanks to an industrial blower fan, etc).
 

SECOND TACTIC:
VENTILATE FOR SMOKE REMOVAL
 

The second tactic is called "ventilate for smoke removal".

1/What does this tactic consist of?
The goal is to move smokes to the outside to replace them with fresh air.
Example: Smoke extraction from a stairwell.

2/What is the advantage of this fire ventilation technique?
Fire smoke, toxic and flammable, represent a risk for witnesses but also for rescue teams.
In addition, although smoke extraction devices are calibrated to facilitate the evacuation of the public, they are rarely suitable for supporting the actions of rescue teams.
 

This smoke extraction will facilitate the action of firefighters because:

• it reduces the quantity of smoke and therefore reduces toxicity,
• it increases the visibility for rescue teams and disaster victims,
• it decreases the temperatures within the volumes,
• it offers more secure public evacuation conditions.

3/How to implement this operational ventilation tactic (smoke extraction)?
Depending on building constraints, we can use a powerful PPV fan called "master fan" at the base of a staircase and relay its action using a portable fan called "relay" in the floors.

The wide range of LEADER PPV ventilators, composed of battery powered fans like the BATFAN or the E-FAN, up to powerful electric fans like the ESV280, allow fast and safe smoke extraction.

BATFAN or EFAN battery fans are perfectly suited to this type of smoke extraction operation. Due to their compactness, LEADER firefighters portable fans will position themselves effectively in traffic lanes while allowing the passage of rescue teams.
 

In special cases, such as underground parking fires, the PARKFAN electric fan range, easier to use than a LFV (Large Flow Fan), offers an unequaled performance / maneuverability ratio for this type of situation!

THIRD TACTIC:
VENTILATE TO ATTACK OR OFFENSIVE VENTILATION
 

Finally, it is possible to implement the tactic of "ventilate to attack".

1/What does this tactic consist of?
This tactical choice aims to circulate the air stream produced by the PPV ventilator through the source of the fire and bring out the gaseous effluents through the closer outlet (opening through which the smokes can exit: window, outlet, etc.). This technique is often combined with hydraulic extinguishing means (one or more nozzles).
 

2/What is the advantage of this fire ventilation technique?
The aim of this tactic is to facilitate and secure the attack on the outbreak. The convective heat produced will be drawn outwards, allowing rescue teams to move quickly towards the fire source.

The air flow produced by the device (PPV fan) reduces the amount of smoke in the volume; increases the visibility of rescue teams; decreases the temperatures within the volume and consequently increases the safety of the teams on site.

However, this technique brings fresh air to the fire and can cause it to grow faster. However, the proximity of the outlet and the pressure gradient provided by the firefighting fan allow to expel quickly the smoke outside.

The main objective of the combined action of ventilation and water is to cool the flames, cool the smoke and especially the fuel. Indeed the projected water, rapidly evaporated, will be carried outside and will therefore not be able to continue its inerting action in the room.
 

3/How to implement this ventilation tactic ?
We will carefully identify the air stream that feeds the fire before and we will facilitate gas flow by limiting barriers and blocking the doors. The outlet (opening through which the smoke can exit: window, outlet, etc.) will be created as close as possible to the fireplace and we will ensure that its size is sufficient to facilitate the exit of the smokes. The pressure gradient created by the firefighting fan will act on the smokes by expelling them towards the outlet, the outlet speed being a good indication of the ventilation efficiency.

For these interventions, the user can count on the reliability of LEADER PPV fans. With a flow range from 28,000 to 128,000 m3 / h and three choices of motorization, all LEADER PPV ventilators are adapted to the most common situations.
 

CONCLUSION 

Operational Ventilation (VO) brings real added value to firefighters. Positive Pressure Ventilation (PPV) allows you to:

• PROTECT : 
  • avoid smokes to enter into a volume;
  • preserve some areas avoiding the spread of smokes and hot gases in the premises to be protected.
• EXHAUST SMOKE : 
  • evacuate the smoke from a room with no direct link to the room on fire,
  • and / or to remove smoke from a volume that has been on fire.
• ATTACK : 
  • act on the smokes and the area on fire
  • channel their propagation,
  • affect the behavior of the fire and
  • allows to decrease the intensity quickly.

The PPV is an undeniable guarantee of safety and, while providing significant comfort for workers by reducing heat and optimizing visibility, it makes it possible to accelerate the extinction of a fire and reduce or stop its spread.

Without training, its implementation can seem complex to the uninitiated.
Already adopted by many firefighters around the world, firefighting ventilation has become an essential element that it is necessary to control in order to optimize your fire engagement and operate in complete safety. It is therefore necessary to train personnel in the use of this type of fire equipment to avoid errors that could disrupt the smooth running of operations.
 

INTERACTIVE VENTILATION COURSES AVAILABLE FOR FREE

To help firefighters wishing to acquire skills in the implementation of ventilation techniques, LEADER, manufacturer of firefighting and search & Rescue equipment since 1985, has developed interactive courses for free download on its website 
https://www.leader-group.company/en/expertises/firefighting-blower-fans/interactive-training-courses-firefighting-ventilation 

Created in partnership with EducExpert, an organization globally recognized in the field of training firefighters, these courses have been specially designed for fire trainers to assist them in their mission. Accessible online by all, the aim of LEADER is to widen the skills and understanding of the use of ventilation techniques.

LEADER ENGINEERS HAVE OVERCOME ALL TECHNICAL OBSTACLES SO THAT NOTHING STOPS YOU! 

By facilitating the control of gas flow thanks to a wide range of fire fans adapted to operational situations, LEADER, offers the guarantee of having reliable PPV fans that meet user expectations. The techniques developed in the new operational guides have been taken into account to guarantee to users an ease of use, set-up and maintenance.

Whatever the models, all LEADER firefighting PPV fans are designed and manufactured with the greatest care and with a high standard of quality and performance. All components and equipment have been designed and chosen for their robustness and reliability.

ACCESSORIES FOR MORE EFFICIENCY: Whichever ventilation strategy is adopted, a wide choice of accessories are available to increase the PPV ventilators’ performance such as the production of foam or the possibility to adaptor ducts to ventilate specific rooms without moving the PPV ventilators.

LEADER, well-known firefighting equipment manufacturer, offers a wide range of PPV firefighting fans.

Discover our other expertises on firefighting fans and firefighting ventilation (PPV, NPV, operational ventilation, etc).