Positive Pressure Fan Firefighting

Offensive smoke ventilation is an entirely different concept from defensive smoke ventilation. During practical training exercises conducted with fire departments, Taizhou Mingxin Firefighting Technology Co., Ltd. observed that many teams were still utilizing smoke ejectors to *extract* smoke-a method known as "defensive" ventilation. True "offensive" ventilation involves *forcing* air into the structure to suppress the fire. Consequently, we have re-engineered this machine to specialize exclusively in "positive pressure air supply."

Internally, we affectionately refer to this YY4.5/5.0-20 Gasoline-Powered Positive Pressure Smoke Ejector as the "Offensive Unit." It has but one mission: to establish a powerful positive pressure zone at the entry point, driving fresh air into the fire scene with the force of a cannon blast, thereby expelling dense smoke and extreme heat out through the opposite end. With a rated airflow of 20,107 m³/h-and equipped with our specially designed air-gathering shroud-this unit can focus its airflow into a concentrated beam capable of penetrating depths of several tens of meters.

In 2023, a fire broke out in a three-story residential building in a certain region of Jiangsu Province, filling the stairwell with billowing smoke. The incident commander issued the order: "Establish positive pressure! Blow it in!" Firefighters positioned the machine at the first-floor entrance; less than three minutes after activation, white smoke began to pour out of the third-floor windows-this was the hot smoke being displaced and flushed out by the influx of fresh air. Two individuals trapped on the second floor were able to successfully escape by navigating the now-cleared stairwell. Such is the power of positive pressure.

Mingxin's engineers have endowed this machine with a "mighty heart"-a GX200 engine boasting a rated power output of 4.5 kW. The defining characteristic of this engine can be summed up in a single word: *stability*. It is capable of operating continuously for extended periods at its rated speed of 3,612 RPM without any erratic fluctuations in performance. Only when the airflow remains stable can a consistent positive pressure zone be maintained; and only when the positive pressure zone remains stable can the risk of smoke backflow be effectively eliminated.

We have deliberately retained a mechanical throttle control system. Why forgo electronic controls? Because a fire scene is rife with unpredictable variables, and electronic components are inherently vulnerable to water, heat, and physical impact. Mechanical systems are a different story altogether: a single lever connects directly to the air damper-pull it to increase airflow, push it to decrease it. It is simple, rugged, and-should it ever break-can be fixed right on the spot with nothing more than a piece of wire.

This machine operates within a working temperature range of -10°C to +40°C. In the depths of a northern winter, you can leave the machine out in the freezing cold all night, yet come morning, a single pull is all it takes to start it up. Conversely, during the sweltering summers of the south, even after baking under the sun for hours, it continues to hum away at full power. True professionalism lies in being uncompromised by the environment.

Both the air intake and outlet are fitted with safety grilles. These grilles aren't there for aesthetics; they are genuine lifesavers. During one test run, a two-way radio was sucked into the intake; it struck the safety grille and bounced right back out. Had that grille not been there, the radio would have shattered the impeller blades into fragments-fragments that would have flown out like bullets.