Aerial firefighting: How effective are water enhancers?

Water enhancers are polymers added to water that improve the water’s fire-suppression characteristics. The cross-linking process of polymers allows them to absorb and retain a very large amount of water without altering its other properties.

Plain water, however, is a very inefficient suppressant. While the water turns into steam and absorbs and carries away heat, it also has a strong surface tension, which causes it to roll off most fuels before it can absorb its full heat capacity.

The most common firefighting agents used in aerial firefighting in the US are water and long-term retardant (LTR) – chemical concentrates mixed with water that alter fuels so that they won’t combust. Colorado only loaded LTR in single-engine air tankers (SEATs) prior to this study.

The cost of water enhancers is significantly lower than traditional LTR, and they are most effective when used for direct attack. However, they are not as effective once they dry.

This study evaluated the effectiveness of water enhancers on wildfires by using SEATs to test and analyze different products: GelTech Solutions FireIce 561, FireIce HVO-F, FireIce HVB-Fx, G5 BioSolutions Blaze Tamer 380 and Thermo Technologies Thermo-Gel 200L.

The study showed that all tested products are effective when used for direct attack; however, different tactics are needed than with LTRs. Further key findings showed that:

• When dropped from a SEAT, water enhancers are more effective in light fuels.
• A prompt follow-up from ground support is essential.
• Differences in mixing and a lack of consistent quality control can be an issue.
• Water hardness and temperature can impact consistency and further studies should be done on this.

When water enhancers are used, about 0.1 to three per cent of gel concentrate is added to the water to increase its viscosity (its resistance to flow) and its adherence to fuels, which minimizes its drift when dropped from aircraft.

To make water enhancers more accessible and efficient to use, the CoE has put together a few recommendations from the study.

Recommendations

The CoE said to generally ‘increase the use of water enhancers, especially during the initial attack’, with further training on the use of enhancers.

The CoE also calls for further studies into the process of quality control, onboard mixing and water chemistry.

Water enhancers should only be used when there are ground firefighters to support the mission, otherwise LTRs are the better solution.

The CoE also calls for further studies into the process of quality control, onboard mixing and water chemistry.

In the report, the CoE stated: “Aircraft are used in a variety of wildfire management roles in many parts of the world. They can be used to deliver suppressants to sections of the fire edge that are difficult to access on the ground and can reduce the intensity and spread rates to allow ground crews to work along the fire edge.

“This is critical during the initial attack of wildfires in remote locations. When used properly, specifically in direct attack on the fire with ground resources present, the CoE’s data showed that there is a favorable reduction in flame heights with the use of water enhancers as opposed to LTR, especially in light fuels.”

Erickson is testing water enhancers now to determine how effective they are. A spokesperson for the company said: “We believe they have strong promise, but are not all created equal. Some are great and others are not great. We are now looking for partners for field testing on live fires for a few selected enhancers.”