County and volunteer firefighters convened around dusk Saturday to perform a training exercise extinguishing a propane tank fire. Set up in the front parking lot of the County Admin Building, a series of tank drills from sunset into dark capped an afternoon of classroom instruction where firefighters gained knowledge on how to attack such a blaze.
For the drill, the burning tank that firefighters attacked contained no bottled gas. Several gas jets mounted in a tank shell simulated the behavior of a gas tank on fire. An Amerigas delivery truck stood at a distance, supplying propane to the drill mock-up through hoses and steel pipes.
Georgia Fire Academy personnel manned valves that fed gas to the mock-up. An oversized supply hose, routing water from a pumper truck, stood charged to the nozzle, a massive one ready to unleash a deluge on the whole tank area if an emergency erupted.
Simulating the performance of a burning tank when the container's pressure relief valve pops open, one instructor-controlled gas valve shot a flame geyser flaring skyward about 50 feet. A pillar of fire lit the night with bright radiant heat––not anything you'd ever want to see in your backyard.
"It gets pretty hot when that pressure relief valve pops off," smiled Glenn Hauss as twilight shadowed deeper. Delivery driver for Amerigas of Ellijay and Canton, Hauss manned the tanker supplying propane for the drill.
In the local area, the company gives propane yearly for drills like this one. The drill's first hour saw 154 gallons flow from the tanker, Hauss said. He was at Ball Ground doing this same thing last summer, he said––at Ellijay the year before.
“This is something where they don't need on the job training,” said Amerigas Manager Barry McNeil, speaking of firefighter preparation for propane tank fires. “They need to have seen it before.”
"Liquid propane expands 270 times when it turns to vapor," McNeil said. "It's liquid in the tank. It boils off and goes to vapor and goes through the lines."
Fire around a propane tank ups the gas pressure inside the tank as liquid propane warms. If the pressure climbs high enough, a safety pop-off valve on the tank top vents gas to keep the tank from bursting. With any flame around, that escaping gas ignites like a massive, roaring blow torch. The blossoming plume of vertical flame can jet 50 feet straight up.
To fight such a tank fire, two teams of firefighters approach the fire huddled side by side, each team manning a fire hose and nozzle. First they cool the propane tank with a straight stream of water from each hose.
As they move in closer, fire teams change their nozzle spray settings to produce a fogging pattern. On this setting, a fire nozzle sends out a broad funnel of fogging water droplets. This bowl of jetting water firefighters use to corral propane flames around a burning tank and push them away from the gas shut-off valve near the top of the tank.
Well fogged and cooled, the valve (which supplies propane to the residence) can be twisted shut to stop the gas flow.
The vertical flame geyser, jetting from the tank's pressure relief pop-off valve, goes away as fire crews cool the tank with straight water streams before approaching closer. That cooling work reduces the gas pressure inside the tank, squelching the geyser flame at the pop-off valve before firefighters begin their close approach to shut off the supply valve to the residence. All gas flames go away after the supply valve is closed.
"You never put a propane fire out until you can turn off the source," McNeil emphasized. Otherwise, you are facilitating the build-up of ignitable gas, an explosion in the making.
As Saturday night's drill progressed, multiple firefighting teams quelled the tank fire, each facing a hellish inferno on the approach. Paid county firefighters and numerous volunteer units took their turns. Lady volunteers of the Tate Rehab Team kept firefighters rehydrated with cold bottled water between bouts.
The same instructors who taught firefighters in the classroom earlier in the afternoon led them through the drill on the ground.
Pickens County Commissioner Robert Jones was on hand to observe until Assistant County Fire Chief Curtis Clark talked Jones into suiting up to join in the exercise. The purpose was to furnish the commissioner with a firefighter's on-the-job perspective.
A drill leader was overheard informing a fire team the commissioner would be joining their group to face the flames. "He's got the heat. He's got the fire. He feels it, and he knows what everybody is doing," instructor Brian Cowart explained to suited, helmeted flame warriors, describing the purpose for Jones’ participation while the commissioner donned fire gear.
Jones occupied the center of the pack as the team moved on the fire, but suited, helmeted and wearing an air mask, the commissioner was indistinguishable from other team members. Battling a fire, firefighters are hard to tell apart.
In the Saturday dark, the drill made an awesome display. First the tall plume flame lit the immediate scene like daytime, beckoning the attack team to make their approach. Two cooling hose streams shot forward at the same level, and the geyser of flame fell from the sky.
Two fogging hose sprays pushed a ball of gas fire close around the tank as hose teams advanced. A third team toted hose behind them to aid the front men. Right up to the tank teams walked, a fog of water separating them from a ball of burning gas on the other side of that cooling spray. One team pivoted its hose spray left, pushing flames off of the tank's shut off valve.
Gas fire, dulled to a soft glow, rolled inside a funnel of fogging spray. One firefighter stepped up to turn the valve and stop the gas. Darkness closed in, all quiet and safe. |
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