U.S. Fire Protection Research Foundation · Firefighting Foams: Fire Service Roadmap, Phase II

No solution has been found for delivering fluorine-free foam to a fire in an oil storage tank

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IMPULSE STORM has solved the problem.

Full-scale fire test on a real storage tank: 23 m diameter, 18 m height, gasoline, full-surface fire, wind above 15 m/s — conditions in which extinguishing by mobile ground monitors is impossible at any capacity of the monitors.

The complete scheme in one frame: the module stands at the tank and delivers super-compressed foam over a few metres. There is no concentrate line, no central foam pump, no proportioner and no multi-hundred-metre working-solution main.

The project of the U.S. Fire Protection Research Foundation (hereinafter US FPRF) “Firefighting Foams: Fire Service Roadmap, Phase II, 2025”, its internal expert correspondence, the research of the U.S. Naval Research Laboratory and the author’s long-standing negotiations with the leaders of the fire services of the Gulf states lead to a single technical conclusion: the transition from aqueous film-forming foam (AFFF) to fluorine-free foam (FFF) in fixed protection systems of large fuel storage tanks is not a replacement of the extinguishing agent, but a task of reconstructing the entire system of its delivery.

US FPRF has no solution for storage tanks

The section on the storage of petroleum products in tanks contains no protection schemes, no design parameters and no delivery equipment. The US FPRF authors confirmed this in their responses to reviewers’ comments. US FPRF has no solution for storage tanks. The entire body of evidence on storage tanks has been delegated to an external source — we have taken this upon ourselves and have proven our own solution.

The required flow increases severalfold

The review of Underwriters Laboratories (UL) listings and Factory Mutual (FM) approvals performed by the US FPRF authors shows that the design application density of fluorine-free foam may be 1.5 to 3 times higher than that of a comparable AFFF system. For individual fuels the gap is wider: gasoline with a ten-percent ethanol admixture requires 6 to 7 times more fluorine-free foam than alcohol-resistant film-forming foam.

To preserve the original pressure losses, a main of 250 mm nominal diameter must be replaced with one of 387 mm. The concentrate stock per tank for a fifty-five-minute discharge grows from 13.3 to 39.8 m³ (author’s calculation per NFPA 11). The ring main diameters are followed by the valves, the fire pumps and the water reserve, since the water supply of a tank farm is sized precisely from the foam demand. There is only one solution here — complete replacement of the delivery system.

Rheology defeats both calculation and pumping

The U.S. Naval Research Laboratory, under program WP20-5373, measured a viscosity of 26,320 cP for a commercial FFF concentrate and characterized the product as a high-viscosity, non-Newtonian liquid. The laboratory’s conclusion is unambiguous: such foams are likely not a direct replacement for film-forming foam and may require redesign of the delivery equipment both on mobile apparatus and at fixed installations.

The problem does not end at the proportioning point. A study of the rheology of fluorine-free foam working solutions (Meyer, Herrera Diaz, Dlugogorski, Fire Safety Journal, 2023, vol. 141, article 103910) showed that the hydraulics of the working-solution mains in all converted systems have been calculated by a formula whose applicability to this medium has been disproven. US FPRF names the same threshold — concentrates with a viscosity above approximately 1,000 cSt. For them, adjustment of the parameters and of the software of the hydraulic calculation is necessary both for the concentrate network and for the foam solution network. Here too there is only one solution — complete replacement of the delivery system according to the results of the recalculation.

The listing covers the pump, not the delivery

The only existing UL listing for positive displacement foam concentrate pumps presented to the market as the solution for FFF concentrates — File EX27020, category GKWT — contains eleven models, and every one of them carries the same limit: a maximum foam concentrate viscosity of 9,320 cP. Neither the shear rate, nor the temperature, nor the measurement method is stated in the record. For a pseudoplastic liquid a single scalar value determines nothing: one and the same product yields 26,320 cP under one measurement regime and 12,644 cP under another, and both values are correct. The conformity of a concentrate to the listing limit cannot be established by the designer, by the facility owner or by the supervising authority. The manufacturer that expanded the listing to 9,320 cP stated at the same time that the design of its products had not changed — that is, the pump is the old one, and the only new thing is the declaration of its new characteristics, which for reasons left unexplained were not stated before.

The listing applies only to the concentrate pump. Therefore the section from the proportioner to the seat of the fire in the tank is covered neither by the UL 162 listing, nor by the pump listing, nor by the responsibility of the manufacturer of the foam, the pump or the proportioner — and it has never been tested on a full-scale tank with a standard fixed delivery system: the tests to which the industry refers were performed at representative scale.

The deadline is set by law

The State of California terminates the use of fluorinated foams at terminals and refineries as of 1 January 2028; the European restriction is moving in the same direction. The owner of a tank farm finds himself between a product that the regulator is taking away and a product whose delivery the existing system does not provide.

The only proven solution

IMPULSE STORM does not improve the transport of fluorine-free foam over hundreds of metres — it eliminates the very need for such transport. The foam is generated under high pressure inside an autonomous module located immediately at the tank, down to a fully underground installation, and is delivered in super-compressed form over a few metres. The concentrate line, the central pump, the proportioner, the multi-hundred-metre working-solution main and the dependence on whether a remote foam chamber will produce the required foam at residual pressure all disappear from the scheme.

This is the only system capable of delivering the extinguishing agent to the seat of a tank fire within the first minute after ignition, preserving the tank, the product and the environment — and with them tens of millions of dollars on every tank. Behind it stands a documented full-scale test programme: more than sixty successfully completed fire tests on real tanks.