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The Adjustable Liquid Atomizing Nozzle



Mr. Paul Fritz
Office of Research and Technology Applications (ORTA)

Naval Air Warfare Center Aircraft Division (NAWCAD)

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The Adjustable Liquid Atomizing Nozzle

With the ban of halons for extinguishing fires on aircrafts, the Navy needed to find a replacement extinguishing medium, for use on its aircraft and ships that was compact, lightweight, non-toxic for personnel, simple and very effective.

The use of water, the universal fire extinguishing medium, would be an ideal replacement considering its high heat of vaporization, low cost, and benign properties. The main detriment of water is the inability to deliver it in a form that maximizes its effectiveness. The typical firefighting technique is to flood a fire with more water than would be required to extinguish it. A novel water delivery method was needed that could supply the optimal minimal amount of water for cooling/quenching the fire temperature and smoothing/suffocating the fire with the steam that is generated. The Naval Air Warfare Center Aircraft Division personnel have successfully developed and tested several nozzles that extinguish fires, using less water, within a faster period of time.

The Naval Air Warfare Center Aircraft Division personnel have successfully developed and tested a nozzle that uses air to push water through a restricted convergent region followed by an expanded divergent region of the nozzle. The rapid expansion of the water and gases in the divergent region causes the water to break up and be atomized into droplets of sizes on the order of 10 to 100 micrometers. This water delivery method uses a minimal amount of water for cooling/quenching the fire temperature and smothering/suffocating the fire with the steam that is generated.

A conventional fire hose and nozzle can produce up to 150 gallons of water per minute – over 100 pounds per minute. The Adjustable Liquid Atomization Nozzle delivers less than 2 gallons of water per minute - less than 20 pounds per minute, with the same fire extinguishing abilities as a traditional nozzle.


Simple Design;
Nozzle can be fabricated using standard machining methods using a variety of metals or composite/plastic materials;

Larger, hand held nozzle systems have been successfully tested and demonstrated at the Pittsburgh Fire Academy by firefighters;

Fires on a three foot diameter oil pan extinguished in 15 seconds or less;

Atomized water droplets have forward momentum, unlike other misting units;

Relatively large nozzle orifice does not clog or become obstructed from dirt or debris in the water;

Since there is a minimal back momentum and a smaller garden size hose is used, nozzle can be easily held in one hand while in operation – unlike conventional nozzles that require two hand operation and often more than one firefighter to maintain control of the nozzle and hose;

Minimal water usage of approximately two gallons/minute compared to conventional nozzles of over 150 gallons/minute.


Utilize in place of and in addition to the standard large water capacity fire hose nozzles;

Nozzles placed on the end of wands, booms and rams that can be poked and inserted into aircraft, basements, attics, rooms, wall cavities, between wall and roof studs, etc. to remotely fog the enclosed rooms and spaces for extinguishing enclosed space fires and quenching hot embers without endangering a firefighter. Nozzle would use minimal water resulting in less water/structural damage to the house or structure;

Use nozzle for fire extinguishing foam systems where it would have the potential of consuming lesser quantities of foaming agents, thus reducing fire fighting costs and minimizing site contamination and clean up;

Replace existing building fire sprinkler systems for public buildings, offices, hospitals, schools, factories, etc.;

Employ stationary, permanently installed nozzle system in restaurant and commercial kitchens and food processing plants. In particular, use above grease fryers where grease fires are a major concern. This system would quickly and effectively extinguish a grease fire in seconds, reducing any fire, smoke and water damage to the equipment and room;

A portable self pressurizing unit, which has been prototyped, can be developed for use in buildings, commercial trucks, various marine craft and larger ocean vessels, aircraft and emergency vehicles such as police cars, ambulances, and EMS vehicles. Using the nozzle maximizes the effectiveness of the water that is carried in the portable unit;

Nozzles are used with transportable water tankers for fighting forest and brush fires. Reduced water consumption would extend range and length of time used by one or two orders of magnitude