High Pressure fire fighting is not a new concept in fire suppression; the use of John Bean pumps, which ran at 800 psi at the pump, 600 psi at the nozzle, pre-dates World War II, when the John Bean Company started making fire apparatus for the US military.
What has changed to high pressure to make it ‘ultra’ high pressure? Why is the new (old) tool better than ever?
What is Ultra High Pressure (UHP)?
National Fire Protection Agency (NFPA) does not define what UHP is at this time. All proposals have suggested that UHP is a minimum of 1,100 PSI. Testing accomplished by the Air Force Research Laboratory at Tyndall Air Force Base indicates that a minimum of 1,100 psi provides the optimal water droplet size and water velocity for maximum throw distance and suppression capability.
UHP’s small water droplet allows for more of the water droplet, up to 90% of the droplet, to be utilized. Less water falls to the ground as a result. Only 10-20% of larger, low-pressure droplets are used with the remainder falling to the ground. The smaller droplets create a much larger surface area to remove thermal energy from the fire. Additionally, smaller droplets easily convert to steam, which has two effects: the steam displaces oxygen from the area and removes more energy from the fire. It takes one calorie of energy to raise the temperature of water from 99°C to 100°C, but it takes 539 calories to turn a 100°C water droplet into steam; when one gallon of water is evaporated, over two million calories of energy are carried away. The smaller water droplets excel at penetrating tiny, more confined spaces (such as vehicle engine compartments) compared to the bulkier low pressure droplets. Think about running through a room carrying a ladder sideways, versus maneuvering by yourself; that is low pressure water vs. ultra high pressure water.
Suppression Capability: Test Results of UHP vs. Low Pressure
Tyndall Air Force Base’s Air Force Research Lab, in conjunction with several UHP manufacturers, including HMA Fire, has determined that ultra-high pressure, defined as nozzle pressure in the range of 1,150 to 1,300 psi, is the most efficient fire extinguishing methodology; efficient equals fastest extinguishment time, lowest use of water, swiftest response time, and least user fatigue. Testing accomplished at pressures below 1,100 psi demonstrated a lack of fire suppression capability when compared to testing at or above 1,100 psi.
The chart above summarises these results. The low pressure systems used a hand line with 11⁄2” hose and a standard pistol grip nozzle capable of fog and straight stream. The UHP system used a 20 gpm pump with ¾” hose and a UHP pistol grip nozzle capable of fog and straight stream. In testing at Tyndall Air Force Base on a JP-8 fire, accomplished in a 3,500 sq ft, 380-gallon test pit, the 20 gpm system extinguished 100% of the fire in 31.5 seconds using 13.6 gallons of water. Low pressure systems (ranging from 95 to 150 gpm, 125 psi) and other ultra-high pressure systems (ranging from 8 to 30 gpm at 1,100 psi) were also tested in the identical conditions. The best low pressure system (95 gpm at 125 using a 1¾” hose) extinguished 90% of the fire in 59 seconds using 95 gallons of water.
In testing accomplished in conjunction with the U.S. Air Force Research Lab at Tyndall Air Force Base in Panama City, FL, a UHP system running at 20 gallons per min, 1,250-1,400 psi at the pump, extinguished fires 50% faster using one-eighth the water as compared to the optimal low pressure system. A UHP 100 gallon skid unit is the equivalent of having at hand over 650 gallons water when compared to a low-pressure system. A 100-gallon low-pressure system (at a range of 90 to 125 gpm) will yield approximately 60 seconds (one minute) of water, while a 100-gallon tank with a 20 gpm system will yield 300 seconds (5 minutes) of continuous water on a single tank of water. With automatic throttle and a low water shutdown, a UHP system can be run by a single firefighter, if necessary.
In 2009, HMA Fire supplied the Vandenberg Air Force Base Fire Department with its Hydrus™ ultra-high pressure firefighting system for comparative fire testing against the Air Force’s standard structural fire equipment. Thermocouples, sensors, and infrared cameras were installed in each of the five houses burned to capture data during the firefighting.
The results were striking. The UHP system provided by HMA Fire, operating at 20 gpm and 1,400 psi outperformed a standard 95 gpm/125 psi system by:
- Consistently extinguishing fires in 50% less time
- Using 80% less water resulting in significantly less interior damage
- Restoring visibility within seconds for improved safety
- Creating no heat roll-back to reduce heat stress
Positive Pressure Ventilation
When using UHP, the speed of the water and the size of the water droplets create positive pressure ventilation; no fans are required.
Ease of Use/Ease of Training
Firefighters interviewed after testing also reported that the HMA ultra-high pressure systems using a ¾” hand line were easier to handle and resulted in less physical strain than the common 1¾” hand line used on fire apparatus. The ultra high pressure line can be handled by a single person, allowing for other attack personnel to view and direct versus dragging and holding line.
With advancement such a automatic throttle control and automatic low water shutdown, no pump panel operator is needed. In conditions that allow, a single person can quickly and safely attack a fire. With the simplification of controls, operators can be trained on the start-up and use of the system in 5-10 minutes.
Quick Response/Fast Deployment
Because of the efficient use of water a UHP system is well suited to fit on smaller, more agile vehicles such as Ford F-Series vehicles or Polaris UTVs. A smaller crew allows for a quicker departure and response time. Several systems have been tested and shown to be operational within 15 seconds of arriving at the scene.
A UHP system units are simple to maintain, designed for Forward Operating Bases in Afghanistan and Iraq. The system uses easy to maintain triplex piston plunger pump, Honda gas engine, Hannay hose reels, and UPF tanks/skid unit. Typical UHP hoses have operational ratings at twice the operating pressures and burst pressures at six times the operating pressures.
UHP vs. CAFS
In testing accomplished by the Canadian DND, the HMA Hydrus water-only system was comparable to CAFS in suppression time while using only 50% of the water used by CAFS. Several UHP systems are foam capable and produce ‘CAFS-like’ foam. A UHP system is less costly than CAFS and virtually maintenance free, requiring no air compressors or air bottles.
Types of Fires to be fought with UHP
Vehicle Fires: Quickness of response, for both the apparatus to the scene and commencement of fire fighting, is critical in combating a vehicle fire. Using a command type vehicle with a UHP system can improve scene arrival and fire fighting activities by 15-20 minutes. Efficient use of water requires no readily available outside water sources (accidents do not always happen near a hydrant). Energetic, small water droplets more effectively penetrate the tight areas of engine compartments (remember the guy with and without the ladder running through a room).
Structure Fires: Studies have demonstrated that fire can double in size every 30-60 seconds. The quicker attacking UHP system can prevent the spread of a fire and keep a single room fire from consuming an entire structure. Because the water is used more efficiently, the residual water left behind is minimal as compared to a low pressure system, causing less water damage and helping the victims of the water to resume occupancy of the structure quicker.
Wild lands: The ability to use a small vehicle to get to places where large apparatus cannot go and the efficient use of water makes UHP a great option for not just controlling, but fighting fire in the wild lands. And when reach/throw distance of up to 60 feet, flames in tree tops can be extinguished as well.
Aviation: UHP systems have demonstrated excellent results on jet fuel fires in testing at Tyndall AFB with adding foam to the water stream. Initial testing in conjunction with the Air Force Research Lab has also demonstrated that UHP systems have proven to be more effective on an engine nacelle fires when compared to a Halon suppression system.
With systems that range from 10 gpm to 100 gpm at greater than 1,100 psi, driven by an independent engine or by hydraulics, there is UHP system available to meet your budget and your fire suppression requirement.
Chief Roy Stock, Cascade Volunteer Fire Department, Dearborn MT
“The inaugural fire for the HMA truck was a vehicle fire. Dearborn was mutual aid to the event and was second engine to arrive on scene. The first engine was a CAF with 700 gallons (of water) and foam and expended its entire water resource on this compact car fire. I was asked to show what we could do with our UHP unit. The car fire was still quite active and coming back to life when I used a fog pattern to kill it. Twenty five gallons of water (no foam) killed the fire and cool the engine enough that the wrecker was comfortable loading on his trailer . . . Impressive!”
Devin Mickiewicz, Captain, Vandenburg Fire Department, Santa Monica County, CA
“What was amazing about [the HMA] UHP was that the hose stream seemed to actually consume the fire. I can’t find a better way to put it than that. When you pointed a UHP semi-pattern at the fire it just went away.”
“It’s lighter (exponentially) and easier to maneuver, sucks the life out of the fire, does amazing hydraulic ventilation and uses about a 10th of the water to the same effect (as compared to a low pressure system).”
“I’m telling you UHP sucked the life out of the fire and did it faster than anything I’ve ever seen before.”
Jeffery Sulalski, former Fire Chief, Ft Leonard Wood, MO
“The [HMA] firefighting unit out-performed our two other ARV units with wild land gas engine driven pumps. The ultra-high pressure pump extinguished tree fires from 30-60 ft in height and ground cover fires very quickly and [with] effective extinguishment. The Polaris ATV climbed 1000 ft hills in some of the roughest terrain with no problem . . .”
“The ultra-high pressure unit uses very little water compared to the other [low pressure] systems we have assigned to our unit.”
For more information, go to www.hmafire.com