Taking the Plunge: New AR-AFFF hits industrial fire market
Success is accomplishing a particular objective, goal or aim. Failure is the inability to achieve success. In industrial firefighting, the main factor that distinguishes the two is the selection of tools, industrial fire protection giant Dwight Williams told firefighters in October.
“Bottom line, what’s the difference between you and me?” Williams asked. “I’m a little older, a little taller maybe than some of you, but not any smarter or braver. It’s the selection of tools and equipment that makes the difference.”
Successful extinguishment is the value of the product saved being greater than the cost of extinguishment, including lost time injuries, Williams told firefighters attending the US Fire Pump Big Water Symposium in Baton Rouge.
Just being on hand when the fire finally goes out does not count as a success, he said.
With more than 100 major industrial emergency operations to his credit, Williams joined with US Fire Pump and AUXQUIMIA Fire Fighting Products of Spain in 2018 to introduce the new Signature Series ™ 1% X 3% alcohol resistant aqueous film-forming foam concentrate to the international fire protection market.
Despite the ongoing environmental debate, fluorinated firefighting foam remains the industrial emergency responders’ best choice for successful extinguishment, Williams said. The product has a long established track record going back to its introduction in the 1960s.
“I’m a performance driven person,” Williams said. “I care about one thing – performance.”
Real world use of non-fluorinated firefighting foam is still extremely limited, Williams said. In some cases, laboratory results have not been encouraging, he said.
A live-fire demonstration conducted during the symposium involved applying fluorinated and non-fluorinated firefighting foam to a full-surface fire of non-ethanol based 93 octane pump gasoline in a 42-inch diameter pan. Williams’ Signature, applied at 0.06 gallons per square foot, extinguished the fire in 41 seconds.
Fluorine free foam applied at three percent took more than three minutes to extinguish a fire of equal size.
Extinguishing the fire quickly is still the best way to preserve expendable resources such as foam and water, as well as protect the environment, Williams said.
“If you’ve put the fire out in half the time you’ve used half the water,” he said.
Beyond the fundamental issue of effectiveness, a host of logistical concerns haunt non-fluorinated foam. Application rate is defined as the measure of quantity of foam applied per unit of time per unit of total area, i.e., gallons per minute per square foot.
“When I was a young lad, a fire chief would look at a fire and say ‘Well, that’s a two-nozzle fire,” or “That’s a four-nozzle fire,” Williams said. “That was a crude way of coming up with an application rate.”
Adhering to the minimum application rate for any foam is akin to supplying a paratrooper with the cheapest parachute available, Williams said.
“Wouldn’t you want to hit the ground a little softer?” Williams said. “Don’t use just the minimum.”
NFPA 11 suggests a minimum Type 2 (over-the-top) application rate of 0.16 gallons per minutes per square foot for storage tank fires. However, non-fluorinated foam might require an application rate as high as .2 gallons to .25 gallons per minute to be effective, Williams said.
“As the tank gets bigger, what does the application rate do?” Williams said. “Try .16 on a 300-foot diameter tank and see what happens. On a 270-footer we used an application rate of 0.2 gpm. That was 12,000 gallons per minute on a 270-foot diameter tank.”
Flame collapse occurred within 12 minutes with extinguishment following 65 minutes later.
“What kind of application rate would you have to use with non-fluorinated firefighting foam?” Williams said. “Maybe 0.4 gpm? Who has the amount of water that would take?”
Fighting fire in storage tanks as large as 250 feet in diameter with 6,000 gpm of water or less available is not unusual, Williams said. The higher application rate may force fire chiefs confronted with a burning crude tank to go defensive rather than attempt extinguishment.
“Save that water so that when the crude comes out of the tank you can knock it back and save the rest of the tank farm,” Williams said.
This phenomenon, known as a boil-over, happens when heat exceeding 700 degrees Fahrenheit descends through the crude beneath the surface fire and reaches a layer of water settled at the bottom of the tank. The water turns to steam, pushing the burning crude out of the tank in a volcanic eruption.
“How fast are you going to set up to hit that crude tank?” Williams said. “A good crew can do it in about six hours. If you’re traveling any distance to reach the fire it might be 10 or 12 hours. What is the oil doing? It gets hot and the heat wave starts moving down.”
In January 1974, Williams observed a boil-over disaster first hand at the Magpetco (Magnolia Petroleum Company) tank farm in his hometown of Port Neches, TX.
“In those days I could run 21 miles per hour,” Williams said. “I know that because crude oil ejected by a boil-over will run across the ground at about 20 mph. I stayed just ahead of it.”
Regardless of fluorinated or non-fluorinated foam, water management at the fire scene is too often neglected while setting up for a foam attack, Williams said. More fire chiefs need to start by turning nozzles off in the process area.
“There’s no place for the water to go,” Williams said. “Now you’re walking around in it. Hydrocarbon floats on top of water. Shut the nozzles off that aren’t doing you any good.”
Using submersible pumps and hard suction hose make it possible to reuse runoff collected in flooded dikes and retention ponds near the fire scene, minimizing the feared contamination from fluorinated foam, he said.
With non-fluorinated foam, air becomes as necessary as water. Unlike fluorinated foam, non-fluorinated concentrate must be air aspirated to produce finished foam.
“Fluorinated foam can be used with a non-expanding nozzle,” he said. “In other words it is shearing in the air on the way to the target, making foam as it goes.”
Because of the smaller bubble size, non-fluorinated concentrate produces heavier foam, significantly reducing the distance it can be delivered by nozzle, Williams said. Improving that range would require incorporating enormous portable air compressors into the fire field equipment set up, making response time longer.
Mathematics combined with experience is needed to calculate the amount of water and foam concentrate needed to attempt extinguishment. Using a 300-foot-diameter tank, the tank radius squared (150 feet times 150 feet) times Pi (3.14159) equals a surface area of 70.686 square feet.
The tank diameter suggests an application rate of at least 0.22 gpm per square foot, Williams said. Even a lower application rate of 0.20 gpm per square foot, using three percent non-fluorinated foam, would consume 424 gallons per minute of foam concentrate, equal to eight 55-gallon drums.
Accomplishing a 65-minute foam attack would require 27,568 gallons of foam concentrate ready and on hand. The total water demand to create the 13,713 gpm of finished foam required would be 891,350 gallons.
By contrast, Williams’ Signature one percent fluorinated foam requires only 141 gpm of concentrate to deal with the same threat in a shorter period of time.
Williams’ patented firefighting methodology involves staging multiple nozzles at angles calculated to create a combined “footprint” or landing zone for foam across the surface of the burning fuel. Correcting the range, length and width of that footprint for variations such as wind, stream width, type and percent of foam concentrate, and the heat of the burning fuel establishes the “foam run” from the tank center to the tank wall.
“Let’s just assume we’ve got a 10,000 gpm application rate on a 250-footer,” Williams said. “How do you apply it? How many nozzles are you going to break into that 10,000 gpm? How about two fives (5,000 gpm monitors) aimed across the center?”
From the center of the tank to the tank wall is 125 feet in any direction. The two 5,000 gpm nozzles produce a 115-foot landing zone on either side of the center. Working together, the nozzles generate a combined foam run of about 80 feet in any direction, Williams said.
Delivering the foam to the fuel surface not only takes a reliable foam product but an experienced nozzle operator. For example, experience teaches what to expect when the foam plunges beneath the burning surface.
“It goes underneath the surface, comes back up and spits product up against the back wall,” Williams said. “It’s not uncommon for it to jump the back wall and set the ground on fire.”
The first appli-cation of foam to the burning surface calls for a special technique known as “teasing,” Williams said.
“You start at one side of the tank and come across it fairly quickly, not more than 12 to 15 seconds to cross the surface,” he said. “Then you sweep across it again.”
The immediate effect is dramatic, Williams said.
“It’s going to get angry as hell the first time you tease it,” he said. “It’s going to make a lot of noise. “
By the third or fourth sweep, the fire starts “lying down,” Williams said.
“The crude oil gets a waxy looking top on it,” he said. “Teasing it changes the vapor yield of the product.”
Without teasing the product first, the monitor operator risks making it jump out of the tank, causing a header fire. The entire procedure takes 12 to 20 minutes to execute with, flame collapse occurring soon after, Williams said.
“Can you expect to put this tank out?” he said. “Yes, if you’ve got a foam that will travel that far, blanket the whole thing and cool the steel with a wet bubble, then you can expect the tank to be extinguished.”
However, the product on fire might not be as conducive to a foam attack as crude oil. Some products can become increasingly water reactive under the right conditions, he said.
“I had a fire in Louisiana that involved several tanks,” Williams said. “One of them was water reactive. The MSDS sheet said different. I said call the manufacturer and ask what happens if you cook it for several hours. The response from them was ‘Oh hell, Dwight, don’t put water on it.’”
Even if the product behaves, achieving flame collapse is not total extinguishment. Again, depending on burning product, a small flame or “ghost” may rise above the foam blanket after application.
“It’s a pain in the can to get that thing to go out,” Williams said.
Often the time needed to achieve total extinguishment is determined by the amount of damage to the tank.
“Have you ever seen an internal floater with the roof blown off?” Williams asked. “It’s a lot of steel, isn’t it, all messed up and tangled.”
Even a minimum amount of damage can present a firefighting challenge, he said. Burning deposits of petroleum coke build up in the folded metal, breaking loose to disrupt the foam blanket and possibly reigniting the surface.
The trick is to strategically spot a smaller nozzle outside the “footprint” to shoot out that last difficult fire. In some cases, final extinguishment may take two hours or longer than flame collapse.
“You have to deploy your resources just like in a battle,” Williams said. “That nozzle amounts to your reserves. You deploy them when you need them.”
Damage can be significant at the bottom of the tank as well. When a sunken roof settles its legs can punch a hole in the tank floor, Williams said.
“It happens about 80 percent of the time,” he said. “At first it can be real small and not a big problem, but it will get worse. After about 30 minutes whatever is in the tank is emptying on the ground where it can ignite.”
Even if the roof settles without damaging the floor, it presents a danger depending on how much fuel remains in the tank. Williams said he has told refinery managers to put product back in the tank as a safety measure.
“I wouldn’t care if they put cold beer in there,” Williams said. “If there is confined space underneath the pan an ignition will blast it out of the tank. If it splits the tank wall, burning product will run out across the ground.”
Negotiating these dangers to achieve successful extinguishment does not end the firefighters’ problems. To protect against re-ignition it may be necessary to maintain a protective foam blanket across the surface of the remaining product.
To illustrate, Williams recalled an incident in New Mexico years ago in which his crew extinguished three burning tanks. Before leaving, Williams warned the firefighters remaining on the scene to maintain a foam blanket on one tank in particular for the next six to eight hours.
“Flying back to the states we stopped in El Paso to refuel,” Williams said. “There was a call waiting. ‘Mr. Williams, we didn’t actually get around to putting more foam on that tank – can you come back and put it out again?’”
Williams said his price for the second extinguishment was the same as the first.
“Two days later they called and asked ‘Do you think we can quit putting foam on that tank yet?” he said.
Beside foam, dry chemical can be an important extinguishing resource, Williams said.
“Count on having pressure fires when you have a storage tank fire,” he said. “The chances are about 50-50.”
The textbook says that pressure fires should be extinguished before any foam attack on the surface fire. Williams said it depends on the circumstances.
“When you have a fire that big what happens when you put out the top second?” Williams said. “It lights off again on the bottom. So you put the pressure fire out just as you get flame collapse on top. You send a team to shoot the pressure fire out just as the bulk of the fire up top is eliminated.”
For many years Williams was closely identified with HydroChem technology, a nozzle that incorporates foam solution or water application with a simultaneous dry chemical application.
“It allows you to shoot out a bigger fire from further away and cool it off while you’re doing it,” he said.
In the days before HydroChem, getting enough range out of a dry chemical extinguisher to perform the coup de grace on a persistent pressure fire could be tricky, Williams said.
“Say the dike is flooded with unignited gasoline,” he said. “You might have to put an aluminum boat in the dike to carry the extinguishers across to put the fire out. Can you see the refinery manager letting that happen today?”
Under the right circumstances, dry chemical can be more
effective on a storage tank surface fire than firefighting foam.
“Go through the eyebrow vent with a 1¼ pipe, put a ¾-inch ‘T’ on the end and discharge dry chemical in each direction,” he said. “If you put one of those every 80 feet you’ll put the fire out with using any foam.”
Used in conjunction with a Type 3 application of water, the fire should go out in only three seconds, he said.
“The tank becomes a confined space,” Williams said. “It’s like a paint booth with a lid on it.”
With regard to the best extinguishing agent or the best firefighting technique, any company that hires a contractor to deal with an emergency should be open to what that contractor has to say, Williams said. He illustrated the point with a photograph capturing the moment an explosion lifted the roof off a storage tank.
Arriving before the blast Williams wanted to begin work immediately out of concern that such an explosion was imminent. However, the company insisted that key emergency personnel meet first to discuss an overall extinguishment plan.
“We all sat down, talked for a minute and then, as we left to start work, the tank roof blew off,” Williams said. “Now we had two tanks on fire.”
The lesson, Williams said, is if you hire a contractor, “it may be worth your time to listen to him.” That wisdom extends to the choice of firefighting foam to do the job, he said.