UHP Firefighting: A Dramatic Leap To Ultra High Pressure

Editor's Note: This is the second in a series providing a comprehensive introduction to ultra-high-pressure (UHP) firefighting.

A perception among today's firefighters is that the ultra-high-pressure (UHP) fire suppression wave hitting North America is rooted in the transfer of European methodology to this side of the world.

Nothing could be further from the truth.

Once upon a time, there were pumps and apparatus manufactured by defunct builder John Bean, a company that many experienced firefighters are able to recall with vivid memory.

The true-to-life Bean, an inventor, began manufacturing products for the agricultural industry about 100 years ago. He set out to build an improved insecticide spray pump, which - legend has it - was used by a farmer to extinguish a fire in an emergency.

By the 1920s, Bean began to market high-pressure pumps that could be installed on fire apparatus. The technology was advertised as a "high-pressure fog firefighter" to be used for all types of firefighting scenarios, such as aircraft rescue firefighting (ARFF) and shipboard, wildland and structural incidents.

The heyday for the Bean pumps was from the late 1940s to the mid-1970s, with the pumps operating between 600 and 850 psi. The system found a small following and was still being manufactured when John Bean's apparatus business was acquired by FMC. The new owner continued to market the pump until FMC ceased production of fire apparatus in 1990.

Although the pump was deemed effective in a number of situations, as building construction and materials for furniture burned hotter than in the past, the Bean pump began to lose its effectiveness. The system was also viewed as ineffective because of its inability to throw water over long distances or penetrate beneath various materials. Ultimately, there was the risk of burns to the firefighting crew.

Terron McLean, chief of the Mattawan Fire Department in southwestern Michigan, has several Bean pumps in-service on his department's apparatus, which were refurbished over the years.

"We love the John Bean high-pressure," McLean said, "so much so that we retrofitted our new American LaFrance pumper with a John Bean pump." In many cases, McLean said, a John Bean is the first-line they pull for a response.

Now, two decades after the last John Bean pump was made, high-pressure firefighting has re-emerged in North America in the more dramatic form of an ultra-high-pressure (UHP) system.

In studies conducted with the Air Force Research Laboratory (AFRL) at Tyndall AFB in Florida, testing centered on producing high-energy delivery of water at 1,100 and 1,400 psi, while flowing 18 to 22 gpm through a 3/4-inch handline or 60 to 70 gpm through a turret. The flow pressure, while significantly higher than the John Bean pumps and traditional European methods, remained safely under the 1,850-psi rate where water could penetrate human skin.

Rory Groonwald, chief engineer at HMA Fire in Madison, Wis. - the company that spearheaded the commercialization of UHP with the AFRL testing - realized that by increasing the pressure, flow rate and delivery method, UHP could have potential value in effectively fighting Class A and Class B fires.

"We'd been having multiple discussions on new topics, when it just hit me how incredibly effective using water in this manner could be," he said. "Shortly after that, I had a new design that could deliver this type of unique technology for the fire industry."

Today's UHP started much the same way as the bulky John Bean system.

The first systems built were complex, multi-stage units with gas-injected foam that produced a fog, but failed to reliably extinguish fire. After trial-and-error, the system was simplified to using a triplex piston-plunger style pump that made the system easier to use and more compact for vehicle installation.

The general principal discovered was that the creation of trillions of micro-droplets converted to steam faster than lower pressure flows, thereby dramatically knocking fire down quicker.

The initial tests with the current design of UHP were performed using JP-8 fuel as the combustible. In half of a 100-foot diameter pit, 380 gallons of JP-8 was ignited and completely extinguished within 34 seconds using only 13 gallon of suppressant. In a test conducted at the National Research Council's fire research laboratory outside Ottawa, Ontario, the same system completely extinguished a 12-by-15-foot room-and-contents fire in 19 seconds using only 6.3 gallons of straight water.

UHP technology was part of a year-long Fire Extinguishing Effectiveness Test performed at Tyndall. Hundreds of tests were conducted on hydrocarbon pool fires using various firefighting equipment that included standard pressure, compressed air foam, combined agent firefighting systems and UHP. The interim report - published in 2004 - stated UHP demonstrated an "exceptional effectiveness," reducing the "amount of agent required by more than 70 percent."

Through structural fire testing, it was discovered the high-energy rate at which water leaves an adjustable nozzle can hydraulically ventilate a room in a fraction of the time that standard pressure can.

As for wildland applications, the stream can penetrate into the ground up to seven inches, allowing for more complete extinguishment, less re-ignition potential and easier mop-up operations.

Further, testing conducted at Tyndall revealed that UHP is effective on aircraft engine fires, dispatching a well-involved jet engine in less than 10 seconds using straight water. Further testing is being conducted to ensure UHP will meet the Flightline Fire Extinguisher Minimum Performance Standard.

Ultimately, UHP firefighting has been tested and validated - with an optimum flow of 18 to 22 gpm - to extinguish most Class A and Class B fires using one-fifth to one-third of standard agent and water application in 60 to 80 percent less time than traditional methods for ARFF, structural and wildland scenarios.

The next time you see a UHP apparatus at a trade show, remember the John Bean pumps fondly, but see UHP technology as a new class of firefighting.

Jennifer Laine is a consultant for HMA Fire, a Madison, Wis., firm that manufacturers ultra-high-pressure fire suppression systems.

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