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7 uses for an apparatus-sized vent fan

Like big fire needs big water, big containers of smoke need big air; here’s a closer look at those units


After many years, I still remember the first big-box store smoke removal problem that I encountered on a fire scene.

The fire occurred in a home improvement store back in some rack storage adjacent to the outdoor lawn and garden section. An improperly disposed cigarette had smoldered into the night and ignited the cardboard boxes of lawnmowers stacked on the racks.

The fire sprinkler system did a great job of keeping the fire small — there were no in-rack sprinkler heads — until we arrived and completed fire extinguishment with a hand line.

That’s when the real problem became obvious. How were we going to get all of the cold, no-buoyancy sprinkler smoke out of the 60,000-square-foot building with high ceilings?

Despite having two truck companies on scene, we only had 12 ventilation fans available: eight electric and four gasoline-powered in all. And all had cfm flows that work great on residential occupancies (13,000 cfm), but not so well on a structure like ours that given a 30 foot height equated to approximately 1.8 million cubic feet.

In our case, the sprinkler smoke had extended across the entire store to a height of about 10 feet, which was still roughly 600,000 cubic feet of smoke that needed removal. It was a long night.

Big wind
As my story illustrates, the blowers of the mid-1990s lacked the size and power to properly provide positive pressure ventilation in buildings with vast amounts of open space.

What we really needed that night was a giant fan, one so big it would have had to be towed on the back of an apparatus.

Modern materials and modern architecture have made the enclosure of vast spaces such as gymnasiums, warehouses, shopping malls, convention halls and high-rise buildings commonplace. Even small towns have huge warehouses, shopping malls and sports complexes that enclose hundreds of thousands of cubic feet of unencumbered space.

An increasing number of fire departments have added positive pressure ventilation as a tactical capability. The ventilation fan manufacturers have responded in kind with a growing number of models and improved technology that deliver greater air flows when they employ PPV tactically to support a ventilation or smoke removal.

Mobile ventilation units
Tempest Technology’s line of mobile ventilation units has several maneuverable, large-flow ventilators that are designed for large volume areas. The airflows range from 130,000 to 150,000 cfm (nominal) and all models can be equipped with a nozzle spraying system that provides misting capabilities for dilution of gases and other airborne contaminants and smoke cooling.

Super Vac’s SVU-50 uses carbon fiber prop that’s powered by a fuel-injected engine to produce 125,000 cfm (nominal) and 250,000 cfm (venturi) of air flow to provide fresh air, remove smoke and contaminants and provide cool, clean air for victims, workers and emergency personnel. The SVU-50 is also outfitted for misting capabilities.

These much larger blowers can be truck- or trailer-mounted and can be mounted on a heavy-duty scissor lift for placing it in elevated positions. With that kind of flexibility, they have at least seven important applications.

1. ARFF and airport operations
They can be used to remove smoke, heat and gases from passenger terminals, large frame aircraft, airport hotels and tunnels.

2. High-rise stairwells
They can be used to prevent smoke and heat from entering stairwells and hallways of high-rise buildings. This will create unobstructed paths for evacuation and fire attack access.

3. Large commercial structure fires
They can control smoke migration in big-box stores, shopping malls and warehouses to enhance safety of first responders and reduce potential property loss. They can also ventilate underground floors and parking areas from ground level.

4. Emergency tunnel ventilation
They can support fixed ventilation systems or control heat and smoke when no fixed ventilation is available. They can ventilate subway tunnels from aboveground positions.

5. Factories and warehouses
They can minimize disruption of operations caused by small fires or chemical releases by quickly controlling and removing heat and gases.

6. Mass decontamination and hazmat
Using the misting capabilities can knock down gases, dilute chemical agents and decontaminate personnel and equipment.

7. Mass cooling
Using the misting function at large-scale outdoor events can be a proactive measure to prevent heat-related injuries for attendees. It can also be used to treat a large number of heat-related injuries at such events.

Who knew there could be so many uses for a really big fan?

Battalion Chief Robert Avsec (ret.) served with the Chesterfield (Virginia) Fire & EMS Department for 26 years. He was an instructor for fire, EMS and hazardous materials courses at the local, state and federal levels, which included more than 10 years with the National Fire Academy. Chief Avsec earned his bachelor’s degree from the University of Cincinnati and his master’s degree in executive fire service leadership from Grand Canyon University. He is a 2001 graduate of the National Fire Academy’s EFO Program. Beyond his writing for and, Avsec authors the blog Talking “Shop” 4 Fire & EMS and has published his first book, “Successful Transformational Change in a Fire and EMS Department: How a Focused Team Created a Revenue Recovery Program in Six Months – From Scratch.” Connect with Avsec on LinkedIn or via email.