[Fire Smoke Exhausters] Advantages of Positive Pressure Ventilation and Smoke Exhaustion and Smoke Exhauster Application

Historically, mechanical ventilation has been used as an indispensable fire protection technology. Back in the 1960s , firefighters used hair dryers to control backfire. In 1960 , several large blowers were used by firefighters to extinguish a fire at a Santa Fe Springs smelter in California. Although mechanical ventilation is a very powerful fire extinguishing technology, he still has its limitations when it comes to dealing with building fires. At the time, mechanical ventilation meant placing a smoke exhauster in a window or other vent to exhaust smoke out of the building. However, placing such a machine in a smoky environment is a tedious process that can increase exposure time in a dangerous environment.

Throughout the early construction material has been changing in the 1970s and 1980s. The increasing use of plastic means that fire will produce more toxic smoke and higher temperatures. Obviously, these simple smoke evacuators cannot accomplish the task of ventilating and exhausting smoke, which forces firefighters to find a better way.

After several trials, Los Angeles firefighters found two points: First, in the building, with respect to the discharge of air (fire pollution), strong cooling and purifying these air is more effective than controlling the flame. The second is to place the exhaust fan outside the building instead of inside, which can improve safety and control over fire. In 1973 , the Los Angeles Fire Department named their discovery as "positive pressure ventilation." This new technology greatly increases the safety of firefighters.

Putting the fume extractor outside the building to increase the positive pressure inside the building has the following advantages:

● Enhanced visibility

● rapid discharge of toxic gases

● Lower temperature

● increase the survival rate

● Reduce firefighters exposure to high temperatures

● Reduce the loss of property in high temperature

● can put the water line closer to the fire

● Reduce the spread of fire due to cooling and rapid containment

● More flexible and lightweight with ventilation technology

● Reduce risk of flashover

Of course this technology is not perfect. Placing the exhaust fan at the entrance of the building will block the entry of firefighters and reduce the rescue speed. The air flow will also weaken and the material will be more easily ignited and bring about smoke hazards.

Positive pressure ventilation allows the balloon to stay far from the ground

At the time, the use of balloons was already common in California. Obviously, there is a need for quick and effective ways to float these huge balloons. Usually, one person needs to look at the balloon, and the other person swings the blower very hard. There is a balloon driver named Ham. He wants to have a breeze that blows his huge hot air balloon to him, but he doesn't need anyone else to blow it with a blower. So he designed a blower that meets his requirements. However, soon Ham and his grandmother found that the design of this blower was of other value besides the hot air balloon.

I heard that the Los Angeles Fire Department test a so-called "positive pressure ventilation," the new fire technology, so Beckham and firefighters work together, his own design effectively applied to the Fire Rescue. In this way, stable electric fan makes ppv reach a new level.

By the late 1990s, a positive pressure ventilator has been as the main fire-fighting equipment, officially put into use in several states, including Utah, Texas, CT, Connecticut and Florida. With the continuous popularization of ppv technology, more and more researches in this area have made PPV continue to make breakthroughs and innovations in air flow, materials, and technology.

Air straightening technology increases ventilator rear distance

In 2001 , air straightening technology became another breakthrough in the design of PPV ventilators. By increasing the fan blades inside the fan, its resistance to high temperatures was greatly enhanced.

Traditionally, PPV ventilators produce a spiral air flow that can only penetrate 2 to 3 meters in air . From the application of PPV technology to the field of fire protection, this distance has not changed much.

Air straightening technology allows ventilators to generate strong concentrated air flow from 2 to 6 meters for efficient ventilation of large buildings. This is like the difference between a DC water cannon and a previous sprayer. The fan's fan guide vanes are able to concentrate the air as a powerful stream of light. In this way, the ventilators can continuously generate strong airflow to ventilate the building without blocking the fire exits and reducing noise.

Ventilator rear distance increase and ventilation noise reduction, but without losing a strong air flow, which makes the firefighting operation become more secure, more convenient and flexible access to the fire exits.

The Universal Application of PPV Technology in Fan LSV

LSV is the equipment used for ventilation of large structures.

Firefighters around the world have realized the practical limitations of conventional on-board 45 to 55cm ventilators. Conventional ventilator is difficult for large buildings effectively ventilated area greater than 500 square meters as well as 1,000 square meters, especially those inside the complex, not a separate single room separated by large buildings. When faced with schools, nursing homes, warehouses and other large buildings, conventional PPV ventilators are difficult to meet the ventilation needs of these large buildings.

Large ventilators with high pressures from 20 to 120 HP are equipped with fire ventilation requirements for large internal buildings that are intricately larger than 100,000 to 240,000 cubic meters. These large-scale ventilators allow the fire department to take full advantage of the PPV technology to deal with the fire fighting and rescue tasks of high-rises, large supermarkets and warehouses.

Through the effective integration of air straightening technology and PPV technology, some movable fans can even ventilate buildings 10 meters away from the building entrance . This substantial rearward movement allows firefighters to overcome the shortcomings of the lack of flexibility of early ventilators and to allow firefighters to enter and exit the fire gate unimpeded. Through other methods such as tilting, LSV can even successfully ventilate multi-storey buildings.

Another comprehensive LSV is more flexible. They can be hung on trailers. Fire engines can even be connected directly to fire engines. This gives the fire department more choice. The use of this integrated LSV in the fire extinguishing of large buildings has become more common in the United States , and it is more economical for the fire department to reduce budget expenditures.

However, large-scale ventilators have greater advantages in terms of eliminating smoke, cooling down, and reducing property loss in firefighting and rescue accidents.

● Airport terminals, airplanes, large hotels and underground tunnels

● Stairwells and corridors in tall buildings

● Large supermarkets and shopping malls

● Subway access

● Warehouse and production facilities

● Reduce firefighter exposure time in carbon monoxide

The engine of the PPV ventilator is mainly electric or started by an internal combustion engine. The motor is less noisy and has no carbon monoxide, but because of its low power, it is not conducive to use in large-scale construction fires. Gasoline engines have large power and are suitable for use in large-scale building fires. However, they are prone to produce more than 50 PPM of carbon monoxide diluted by air, which increases environmental pollution and affects the health of firefighters.

Infrared imager can be perfectly combined with smoke exhaust ventilation

Infrared imagers ( IR ), often referred to as thermal imaging cameras ( TICs) , have made greater breakthroughs in the fire safety of firefighters. In addition to the superior performance of these instruments in the search for victims, they can also play a greater role in detecting heat load and heat transfer during PPA or positive pressurization ( PPV ) operation.

A relatively big concern for PPV technology is how to reasonably set up exports to effectively cool buildings and eliminate smoke. The on-site commander of the fire brigade is responsible for assessing the situation on the site, rationally arranging equipment and personnel, and rationally setting up the import and export of fires to control the order at the scene. The integration of TIC into PPV not only allows us to see the distribution and degree of high temperature, but also the dynamic three-dimensional movement of heat load can be seen by us and analyze it to find the cause of the accident and the consequences. This kind of feedback assessment is very important to ensure the safety of firefighters in firefighting and rescue. In firefighter training, the TIC can help trainers to form a visual image in the mind to help them describe the reasons and effects of using various ventilation technologies.

The advantages of IR include the following:

● Play a very important role in firefighters' PPV and PPA training

● Lock the heat source caused by unintentional unreasonable ventilation

● Observe the high temperature distribution map to find the center point of the fire

● can quickly lock trapped people

● Save lives and property

● Discovered loopholes in the building's fire protection

The information in this article comes from the Internet and was reorganized and edited by China Rescue Equipment Network.