In the days leading up to Operation Iraqi Freedom in 2003, when the Air Force was looking to increase its firefighting effectiveness with systems that could be air-dropped into remote locations, scientists at Tyndall Air Force Base, in Florida began developing and testing high-pressure foam systems, or ultra-high-pressure (UHP) foam systems as they are sometimes called.
|A truck-mounted high-pressure foam system.|
The scientists found that using very high pressures – 1,500 psi and above – dramatically increased the extinguishing capability. And they did it with a lot less water, so systems could be a lot smaller and still deliver the same firefighting power of traditional high-flow systems.
The average fire truck uses low pressure and high flow to fight fires, delivering water and other firefighting agents, at pressures ranging from 100 to 250 psi.
An ARFF In Baghdad
The Tyndall team put a high-pressure system on a 1,000-gallon P-19 airport rescue firefighting (ARFF) truck, which was deployed in Iraq in 2003 and successfully fought its first fire at Baghdad International Airport using just 50 gallons of water.
Doug Dierdorf, the fire research group lead scientist at Tyndall AFB, was quoted in the Air Force News in 2004 as saying, “With 500 gallons, we are able to put out a fire as we would have [with] 1,500 gallons using a conventional firefighting system. This 3-to-1 advantage [could] give us a fire truck half the size of the P-19… It turns out the high-pressure water gives us better penetration, better dispersion.”
Since the original deployment on that P-19, the U.S. Army has put 31 high-pressure foam skid units on Kubota Fire-Rescue Rough Terrain Vehicles (FRRTVs) and deployed them at forward operating bases in Afghanistan. The ability of high-pressure foam systems to effectively fight fires with a very limited water supply and their ease-of-use have made them an ideal fit with this application. In addition, the Air Force Research Lab at Tyndall AFB has been testing commercial systems with great success.
High-pressure foam systems are not new-to-the-world technology, but in recent years they have undergone design improvements and extensive testing, which makes them a highly effective option to consider for brush, car and even structural firefighting.
High-pressure, or ultra-high-pressure foam systems, push water through a small orifice at extremely high pressures – from 1,500 to 3,000 psi – to create tiny water and foam droplets that separate the fire from its fuel source and oxygen to effectively extinguish the fire. The foam then penetrates, clings and coats to prevent the fire from re-igniting.
The benefits of high-pressure foam systems are numerous:
- More knockdown power and firefighting capability per gallon.
- Increased firefighter safety. High-pressure systems rapidly reduce temperature and also provide positive pressure ventilation to help increase visibility inside a structure.
- Less water consumption – up to two thirds less – for the same knockdown and suppression capabilities of traditional firefighting systems. Departments familiar with using compressed air foam (CAF) on brush/wildland and structural fires notice that with high-pressure foam systems you need a lot less water for the same effect as with CAFS. For structural fires, it means you minimize water damage and cleanup.
- Systems are extremely compact because pumps and components are small, and smaller water tanks are needed. This means you can consider adding firefighting capability to smaller units such as RTVs, quick attacks, minipumpers, brush/wildland, and small “wet” rescues. For departments struggling to expand capabilities under tight budgets, this makes for an alternative worth considering. This also makes high-pressure systems ideal as a secondary or supplemental system on larger rigs.
Simple To Operate
- Easy to operate. Some systems are as simple as turning them on and selecting foam or no foam. This eliminates training and maintenance issues sometimes associated with more complex systems, such as CAFS.
- Reduces training and increases adoption in the field. For departments that like the effectiveness of compressed air foam, but just can’t get it into consistent use because of the complexity, a high-pressure foam system offers an excellent alternative. In fact, this is one of the reasons that the U.S. Army has deployed Fire-Rescue Rough Terrain Vehicles equipped with high-pressure foam systems in Afghanistan. It takes just minutes to train a soldier to use the system effectively.
- Remarkably lightweight hose makes it easy to handle the nozzle and direct the water/foam stream.
High-pressure systems can be PTO-driven or hydrostatic pump-driven or powered by a diesel engine or gas engine. For RTV applications, it’s good to consider a unit that offers a hydrostatic pump drive system instead of one where you have to add another engine pump, increasing cost and complexity. For airports and other high-flammable fire ground sites, a diesel-driven system is really the only choice.
Two main types of high-pressure foam systems are available: premix systems and those that meter foam and water separately. Either can be effective, but using a system with a separate foam tank allows for sustained fire ground operations, whereas a premix system provides for “one shot” and requires you to stock premix, which may not be part of your department’s normal inventory.
Combination systems – combining high-pressure and high-flow systems – in an integrated package can provide the best of both worlds and allow firefighters to get comfortable with this new type of system while still having the familiar high-flow option available.
High-pressure systems are manufactured by E.J. Metals, Rosenbauer and HMA Fire Apparatus. Each offers systems that have been extensively tested. In addition, FoamPro just introduced a high-pressure system.
Editor’s Note: Kevin Quinn is president of E.J. Metals and a 32-year fire technology industry veteran. He is the developer of the Assault Force high-pressure foam system and Assault Force 70/70.4 Fire-Rescue Rough Terrain Vehicles. He holds a patent on the EJM TRIPLEX high-pressure nozzle, designed to optimize high-pressure foam system performance.