The Art of Making Foam

Foam chemistry is a delicate balancing act. A large component of this year’s Xtreme Industrial Fire & Hazard Training conducted at Brayton Fire Training Field involved acquainting industrial firefighters with the conflicting factors that make new fire foams difficult to develop.

The basic challenge remains the same, said Dewey Morrison, a chemist with Williams Fire & Hazard Control who has worked on the formulations of various foam and dry chemical products.

“You’ve got a fuel and you’ve got oxygen trying to get to that fuel,” Morrison said. “Then you have flames.”

The roll call at the 26th anniversary of the Williams F&HC summer foam school included 244 participants representing 12 countries. Participants included industrial firefighters as well as those who represent municipal fire departments, rail response specialists, pipelines, terminal and refining facilities.

Thirty of those participants served as instructors during the four-day training event conducted at the Texas A&M Engineering Extension Service fire school in College Station, TX.

“A very diverse group representing all facets of firefighting from industry as well as the municipal sectors attended,” a Williams F&HC spokesperson said.

Morrison not only addressed the XTREME general session but conducted special foam chemistry classes that allowed participants to mix their own fire foam products, balancing the issues of cost, viscosity and oleophobicity, the physical property of a molecule that is repelled from oil.

Specifically, these issues continue to hinder the development of non flourinated fire foam, Morrison said.

“Why don’t we have one that works?” he said. “Well, the current technologies out there, the ones we’ve developed and the ones we have evaluated all have limitations.”

By its very nature, synthetic non fluorinated foam lacks the ability to create the film that makes aqueous film forming foam (AFFF) so successful, Morrison said.

“Since we don’t have access to the oleophobicity we have to rely on making a really, really good high expansion foam with a really long drain time and good heat resistance that allows it to hold on to water,” he said.

To get higher expansion means increasing the hydrocarbon loading capacity of the non fluorinated foam, allowing it to create more bubbles. In turn, that makes the foam more susceptible to fuel contamination.

“Another thing that chemists have been doing is really upping the amount of polysaccharide loading, the complex sugars that bond together,” Morrison said. “That gives it better heat resistance and longer drain time. But that leaves me with a product that is a higher viscosity to work with.”

Polysaccharides are more commonly used as a thickening agent in food processing, he said. Thickening creates problems in pumping and proportioning foam.

“We don’t want it thicker,” Morrison said. “We want it close to Newtonian, as close to water as possible.”

Separation of the polysaccharides and the surfactants in the foam often happens. The increase in surfactant loading also means increased toxicity, he said.

 Other issues addressed in classroom sessions included application rates and density, use of Footprint methodology in full surface tank fires and dealing with a variety of other emergencies ranging from fixed roof fires to rail car derailment.

Williams Fire & Hazard Control technical sales engineer James Morgan focused on mobile proportioning in his address. Advantages of a pump based foam proportioning system includes being easy to operate and maintain, the ability to proportion Class A or Class B foam concentrates and being able to accurately proportion foam concentrate to all or to selected discharges and maintain accuracy through varying discharge rates.

Among the drawbacks is that the systems are rarely tested, mainly due to a reluctance to get foam on the ground, Morgan said.

“They are not flushing the systems out as recommended,” Morgan said. “When they do test them they are not testing them to the full range of their capabilities. They are simply testing to see if it works.”

Justin Wright, also with Williams F&HC, spoke on the challenge of calculating and then obtaining the resources needed for a foam attack on a burning large-diameter storage tank. As an example, he calculated what would be needed to deal with a 311-foot (94.8 meter) crude oil storage tank.

Based on the Williams F&HC recommended application rate of .24 gallons per minute/feet2 (9.78 liters/meters2) extinguishment will require 18,231 gpm of water/foam solution.

At a one percent application rate, the attack will require 183 gallons per minute of foam concentrate. Calculating for a 65 minute application, firefighters must locate 11,895 gallons of foam concentrate.

“Even for a 150-foot diameter tank you are going to be in the 6,000 gallons a minute of water/foam solution,” Wright said. “It’s not an inconsiderable amount of water.”

Paul Nony with the Center for Toxicology and Environmental Health addressed the importance of air monitoring to better manage exposure to material with no established occupational exposure limit. Cited as an example of such an event was the July 2013 train derailment and explosion that devastated the town of Lac-Mégantic in Quebec (“Braking Bad,” IFW, Winter 1014).

“We document what happens at the incident,” Nony said. “Where did the chemicals go? Where did they not go? We also take note of the lessons learned by every responder.”

The effect of frequent and prolonged exposure to smoke at a fire scene is responsible for a 25-to-40 percent increased risk of severe life threatening health issues among firefighters, he said.

“No job is so important that it cannot be done safely,” Nony said. “But you still have people who will say ‘You know, I can see right through this smoke – it’s not that much,’ or ‘we’re only going to be in there a couple of minutes.” Tony Coe, a firefighter with 32-years’ experience in firefighting and fire protection engineering, addressed emergency pre-planning for storage tank fires. Firefighters attending the conference had spent the last three days acquiring important bits and pieces of specialized information about emergency response, he said.

“All this talk about application rates and foam equipment is like pieces of giant jigsaw puzzle,” Coe said. “The job now is to put that information into a format that is a bit more user friendly when you have to use it at 2 o’clock in the morning.”

Carl Anderson of PetroSafe Technologies spoke about the importance of knowing the first thing to do in an industrial emergency. Unfortunately, progress in greatly reducing the number of such emergencies tends to promote complacency in some fire brigades.

“Less emergencies means we are losing our core of experience,” Anderson said. “I bet there are some of you here that have never seen a bad one.”

Continuing to train to cope with the worst disasters possible can only help firefighters do a better job dealing with the more routine challenges of their job, he said.

In a long established tradition, Williams F&HC personnel demonstrated a crude oil tank boil over using a scale model storage tank. Despite pre-heating the oil before igniting the full surface fire, the tank still took nearly a full hour to boil over.

Training also included two days on the Brayton Fire Training Ground conducting live-fire exercises utilizing full size training props represent fires aboard a ship, involving a derailed train car and a simulated storage tank used for full surface and seal fires. On the fire field pond, Williams F&HC demonstrated an 8,000 gpm submersible pump, an 8,000 gpm firewater pump and several 6,000 and 1,500 gpm firewater pumps.

Various end of line devices from 95 gpm to 12,000 gpm were available for attendees to use.