Scientists develop retardant gel with “persistent retention”qualities

It could be used to pretreat areas at high risk of fire ignitions to make them fire resistant

long term gel fire resistant
Overhead time-course images of 3 m × 3 m unmowed (standing) grass plots that were untreated or treated with different coverage levels, dried, weathered, and allowed to dry again over time in the environment prior to burning. The normalized area burned over time demonstrates that CL2 (coverage level 2, or 2 gallons per 100 square feet) is sufficient to preclude spreading of the fire. Air tankers use the same unit of measurement, coverage level, to specify how much retardant will be dropped. Figure from the research.

(This article first appeared on Wildfire Today.)

A group of scientists and engineers have developed a new fire retarding chemical, actually a gel in this case, that they say can be effective for months after being applied to vegetation.

The millions of gallons of red fire retardant that air tankers drop every year is usually made from ammonium phosphate or its derivatives. It has  been called “long term fire retardant” because even after it dries, the chemical can interfere with the combustion process and may still retard the spread of  a vegetation fire to a limited degree. However research and experience in the field has shown some formulations can be toxic to fish.

Gels have been used by firefighters for several decades on structure fires occasionally on vegetation fires. The products can be more effective than plain water due to their ability to stick to a vertical surface or vegetation. Water can remain in the gel for an hour or more depending on the ambient temperature, wind, and humidity. GelTech Solutions recently received a contract from the Oregon Department of Forestry to supply a blue-colored version of FireIce HVB-Fx gel to be used in air tankers. The company says the product passed the U.S. Forest Service’s newly revised, more challenging requirements for wildland fire chemicals. But the safety data sheet for the product says, “Titanium dioxide [a component of the product] has been classified by IARC as a possible carcinogen to humans (Group 2B) through inhalation of particulate dust.” The safety data sheet goes on to say, “This classification is based on inadequate evidence for carcinogenicity in humans, but sufficient evidence of carcinogenicity in animals (rats). It should be noted that recent studies have demonstrated that the rat may be particularly sensitive to high levels of toxicity dusts such as titanium dioxide. Epidemiology studies do not suggest an increased risk of cancer in humans from occupational exposure to titanium dioxide. The conclusions of several epidemiology studies on more than 20,000 TiO2 industry workers in Europe and the USA did not suggest a carcinogenic effect of TiO2 dust on the human lung.”

This is not the first time blue gel has been used in air tankers. The photo below was taken in the Black Hills of South Dakota August 15, 2006.

blue gel air tanker fire retardant
A single engine air tanker drops blue gel on a fire near Shep’s Canyon in the Black Hills of South Dakota August 15, 2006. Photo by Bill Gabbert.

The scientists who developed the new fire retarding gel that they claim has “persistent retention”qualities said their formulation is environmentally benign, nontoxic, and will “biodegrade at desired timescales.” After application, it will retain its ability to prevent fires throughout the peak fire season, even after weathering that would sweep away conventional fire retardants. The cellulose-based gel-like fluid stays on target vegetation through wind, rain and other environmental exposure, they said.

“This has the potential to make wildland firefighting much more proactive, rather than reactive,” said Eric Appel, the study’s senior author and an assistant professor of materials science and engineering.

Treating wildfire prone areas prophylactically could provide a highly targeted approach to wildfire prevention, but, until now, long-lasting materials have not been available.

The researchers have worked with the California Department of Forestry and Fire Protection (CAL FIRE) to test the retardant materials on grass and chamise — two vegetation types where fire frequently starts. They found the treatment provides complete fire protection even after half an inch of rainfall. Under the same conditions, a typical commercial retardant formulation provides little or no fire protection. The researchers are now working with the California Department of Transportation and CAL FIRE to test the material on high-risk roadside areas that are the origin of dozens of wildfires every year.

“We don’t have a tool that’s comparable to this,” said Alan Peters, a CAL FIRE division chief in San Luis Obispo who monitored some of the test burns. “It has the potential to definitely reduce the number of fires.”

The Stanford-developed treatment contains only nontoxic materials widely used in food, drug, cosmetic and agricultural products, according to the developers. The unique properties of these gel-like retardant fluids allow them to be applied using standard agricultural spraying equipment or from aircraft. It washes away slowly, providing the ability to protect treated areas against fire for months as the materials slowly degrade.

Link to the research paper, “Wildfire prevention through prophylactic treatment of high-risk landscapes using viscoelastic retardant fluids”.

Thanks and a tip of the hat go out to Tim, Carl, and Kelly. Typos or errors, report them HERE.

Tanker 116 sees action at Phoenix

Above: Air Tanker 116, an HC-130H, sprays retardant on a fire near Phoenix, June 22, 2017. Fox 20 Phoenix.

Tanker 116 saw some action today, dropping on a fire near Phoenix that closed Interstate 17. Fox 10 got a pretty fair shot of the drop, but unfortunately the camera operator, perhaps not experienced in covering air tankers, followed the aircraft very closely all the way through the drop so it was difficult to tell which of the two parallel retardant drops was made by T-116. Yes, there were two drops parallel to each other. One looked like it was very wide but the coverage on the ground was very thin. The other was much more narrow and and had better coverage.

The video below shows the drop, and I found it at 2:40:45, but when I first saw it, it was at a different time stamp. The video should begin a few seconds before that point, but it you don’t see it there, check a couple of minutes on each side.

The image below shows the two parallel drops. It is difficult to tell from the video which one was made by the HC-130H.

retardant drops
The two parallel drops can be seen at the lower-right. Screen grab from the Fox 10 video.
The news people in the audio have some problems with aircraft ID in that video and at another spot in the same video. At about 2:22:15, there is a second drop and you will hear the news people identifying a lead plane as a Single Engine Air Tanker and what is either an RJ85 or a BAe-146 as a DC-10.

About 2 to 3 minutes after that second drop, a third drop (at 2:25:45) is similar to the second one, and is possibly the same but from a different angle. I am fairly certain this third drop is an RJ85, since you can see the pregnant bulge on the belly.

The very lengthy video goes back to a fire near Los Angeles several times. The image below, a screenshot, show a retardant drop that affected several homes.

retardant drop houses Los Angeles
Retardant gets dropped on homes at fire near Los Angeles. Fox 20 Phoenix.
T-116 is using, not a conventional gravity retardant tank, but a pressurized Modular Airborne FireFighting System rig that is normally only used in military aircraft that have been temporarily drafted into an air tanker role by loading a MAFFS unit in the cargo hold. The compressed air that blows the retardant out of the 3,000-gallon tank sprays it out of a nozzle, breaking the thickened retardant into very small droplets. T-116 and six other HC-130H’s are in the process of being transferred from the Coast Guard to the U.S. Forest Service. If the process is complete by the end of this decade as the agency expects, all seven will have conventional gravity-powered retardant delivery systems and will be operated and maintained by contractors, but owned by the USFS.

Thanks and a tip of the hat go out to Tom and Brian.
Typos or errors, report them HERE.

Colorado studying SEAT-dropped water enhancer effectiveness during 2017 wildfire season

Above: State-contracted SEAT T-831 drops sunset orange FireIce HVO-F®. Courtesy photo.

Efforts are underway in Colorado to better evaluate how water enhancers delivered from a single engine air tanker can be more effective than retardants in fighting wildfires.

Colorado historically has only loaded long-term retardant into SEATs. These chemical concentrates are mixed with water and alter fuels so they do not support combustion. Retardant is dropped adjacent to — or ahead of — the fire to create a chemically induced fire break at its perimeter.

Molecular bonds from water enhancers, however, slow evaporation by creating a thermal protective coating. SEAT drops of water enhancers are mainly used in direct attack to slow or halt the fire’s rate of spread long enough for ground resources to access the fireline and mop up or supplement the knockdown process.

These gels have generally been limited in use in recent years, and field testing has been minimal. Information about water enhancers’ availability, use and effectiveness is sparse at best.

The study, lasting throughout the 2017 wildfire season in Colorado, has the following objectives, according to the Colorado Division of Fire Prevention and Control:  

  1. Observe and evaluate drops of water enhancers on wildfires and record information about 1) whether the water enhancer stopped or slowed the forward advance of the fire; 2)whether the water enhancer reduced fire intensity to a sufficient level for ground crews to manage the fire; and 3) whether the water enhancer persists on the surface fuels long enough to prevent hotspots from redeveloping or the fire from burning through the drop.
  2. Determine whether water enhancers delivered from a SEAT are effective on wildfires in Colorado. Effectiveness will be viewed in terms of how effective the products were in achieving the desired suppression objectives.
  3. Collect as much data as possible regarding the effectiveness of water enhancers used during initial attack and on emerging fires.
  4. Share lessons learned from the evaluations with interested parties, including cooperators and researchers.
  5. Test and evaluate newly developed ground-based mixing/batching equipment to assess the efficiency of the mixing and loading processes and the ability of the equipment to reduce response times.

“SEATs loaded with water enhancers will respond to fires on State and private land, as well as to fires under the jurisdiction of BLM, the National Park Service, and USFS. Mixing will be at the recommended ratios in the USFS Qualified Products List for each product on all drops. For the first load on each fire, State and Federally contracted SEATs will respond to the incident with water enhancer unless the ordering unit clearly specifies the need for LTR instead.

Decisions regarding where, when and how to apply a particular aerial retardant or suppressant are typically under the discretion of the Incident Commander, so if at any time the Incident Commander or the Air Tactical Group Supervisor feels that the enhancers are not performing as desired, the Incident Commander can immediately order that the SEATs be loaded with retardant.

The three water enhancers being evaluated in the study are: FireIce HVO-F, BlazeTamer 380, and Thermo-Gel 200L — each is approved by the U.S. Forest Service for use in SEATs.

The Center of Excellence for Advanced Technology Aerial Firefighting, with support from the Division of Fire Prevention and Control’s Aviation Unit and the Bureau of Land Management, is conducting the study.

After weighing input from researchers and firefighters, investigators will compile a preliminary and final report about the project’s findings.

Throwback Thursday: Monsanto ad

Phos-Chek
Vintage Monsanto ad for Phos-Chek.

For Throwback Thursday, here is a look at a vintage ad in which Monsanto is advertising Phos-Chek fire retardant. The ad includes the date, 1977.

The aircraft appears to be a C-119 which last flew over fires when? In the late 1980s? I seem to remember that one fell apart in mid-air while I was fighting one of the hundreds of lightning-caused fires in northern California in 1987. (UPDATE Nov. 21, 2014: we heard from Dale, who told us: “You are correct about the year of the C-119 crash in Northern California. There were 3 people on the airtanker when it crashed. The next day, Buzz Dyer, the USFS Airtanker Program Manager grounded all C-119’s from flying for the FS again.”

You can still see two C-119s at the Greybull Rest Area in Wyoming.

C-119
C-119 on final, about to drop on a fire, ~1972. Photo by Bill Gabbert.

Demonstration of fire retardant effectiveness

This video, featuring Shirley Zylstra, the Wildland Fire Chemicals Program Leader for the U.S. Forest Service, demonstrates the effectiveness of long term fire retardant dropped by air tankers, and occasionally by helicopters. In the video that was uploaded to YouTube yesterday, Ms. Zylstra explains how the chemical works even after the water evaporates by interfering with the combustion process.

The video is extremely low resolution, 240p, and looks like it was recorded with a flip phone, but it gets the message across.

Photos of aircraft at Aerial Firefighting conference

CAL FIRE OV-10
CAL FIRE OV-10

We took these photos last week, March 20, at the Aerial Firefighting conference in Sacramento. There were about 90 minutes set aside for displays of firefighting aircraft at McClellan Air Force base, as well as live demonstrations of water and water pellet drops from a helicopter, and the use of the AirTEP Airborne Tactical Extraction Platform marketed by Aerial Machine Tool. We have photos of Coulson’s C-130Q in another article.

CAL FIRE T-83, an S2T
CAL FIRE T-83, an S2T
Croman S-61 dropping water
Croman S-61 dropping water
Croman S-61 with modified tank for water pellets
Croman S-61 with modified tank for water pellets

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