CHOOSING A NOZZLE

CHOOSING A NOZZLE

BY ANDREW O`DONNELL

What`s the better nozzle–the smooth bore or the combination? This subject, in all likelihood, will be debated until the end of time, without total agreement. This is good because one tool cannot do it all. No fire engine should be equipped exclusively with just smooth-bore nozzles or combination nozzles. Each has its rightful place in the fire service.

When listening to the smooth bore vs. combination debate, one matter that has always bothered me is the mixing of terms that mislead the student. When I refer to a smooth-bore nozzle, I mean a nozzle that can be described as an open, round, tapered tube that ejects water in a straight, solid pattern. The combination (or adjustable) nozzle is one that only discharges a stream in some form of fog or spray pattern; it is capable of throwing a variety of water shapes, from the straight stream to wide-angle fog and every angle in between.

Firefighters deliver water in many different ways for many different purposes. Because there is such a variety of purposes, we should have a variety of nozzle types and sizes available on our apparatus. This need may vary considerably from department to department and from district to district. One department alone may contain rural areas, single- and multiple-family dwellings, commercial occupancies, heavy industry, high rises, and other special hazards. We must consider all purposes when equipping our engine companies.

But at the center of the smooth-bore vs. combination-nozzle debate is the question, What`s best for the 134-inch interior attack handline capable of delivering about 150 gpm?

Based on my own experience and testing, I am inclined toward the adjustable/combination nozzle for an interior attack handline. I am well aware of the need to use a straight- stream pattern in most interior attacks. In my earlier days on the busiest engine companies in Chicago, it didn`t take me long to learn that you don`t stand in a doorway and use a fog pattern to fight fire in an enclosed area. Upsetting the thermal balance can get you in a heap of trouble. It may get you burned, limit your visibility, and delay rescues and extinguishment. Improper use of fog streams can push the fire into uninvolved areas of the structure.

Arguments flourish over the quality of the streams produced by adjustable nozzles, particularly in straight-stream mode. I have been involved in many comparison tests of nozzles without the help of salespeople or other biased interference and conclude that, first, all nozzles vary from manufacturer to manufacturer (depending on quality of design and workmanship in eliminating water turbulence within the device) and, second, in the real world of interior structure firefighting, the difference between smooth bore and straight stream, in terms of direct attack effectiveness, is negligible.

What are we looking for in an interior attack nozzle? Do we want a great solid stream because we need the slight added advantage of better reach and penetration? If we desperately need that extra reach and penetration for an interior fire, it sounds to me like we`re talking about larger hose and greater nozzle capacity for a big fire. Or are we looking for a nozzle with versatility, one that is effective as an initial attack line and for a variety of other functions?

The combination fog nozzle on interior attack lines gives us firefighting capability if we run into a flammable liquid fire, such as a fuel oil spill or a fire in a clandestine drug lab. We also have the ability to use the indirect method of attack on a structure fire if conditions warrant. A good fog pattern is available should quick ventilation be needed. It also provides limited protection for firefighters in situations in which they have to exit a building under untenable conditions.

The combination nozzle also may be needed to double as the company`s foam nozzle. It`s also the nozzle that would be pulled for an auto fire, a propane barbecue grill fire, and so forth.

Adjustable nozzles also have the ability to digest excessive pressure being sent by the pump operator. Overpressurizing a smooth-bore nozzle will result in a poor-quality, hard-to-manage stream. Throttling down will only result in a totally distorted stream. With an overpressurized combination nozzle, slightly throttling down on the shutoff until the stream is manageable will still maintain an operable stream. During overhaul, partially opening the adjustable nozzle conserves on water and water damage.

There are, however, some disadvantages to the adjustable nozzles, too. Clogs in the nozzle, slightly increased back pressure, and increased purchase and maintenance costs are all factors to be considered. Also consider pressure available from remote standpipe outlets in your high-rise buildings–it will not be enough (in most cases) to provide a good-quality stream out of your combination nozzle.

Adjustable nozzles have changed dramatically in the past few years to be more competitive in light of the return of the smooth-bore nozzle. The manufacturers, at the urging of the fire service, have reduced the pressures required to operate fog streams. Low-pressure adjustable nozzles are available and help reduce the firefighter fatigue associated with the older nozzles that operated at 100 psi. Retrofitting the older-style adjustable nozzles to lower operating pressures may be an economical solution to the department with limited purchasing power.

The best way to decide on the nozzle that best suits your department is to take the time to perform an extensive evaluation of all nozzles available. First, pick your desired flow, identify your intended purpose, add in other tasks you may have to accomplish with this nozzle, and make your determination. A thorough comparison of all nozzle types, models, and manufacturers will reveal some surprising results.

After some very exhaustive tests and trials, taking the long-and-careful approach, our department chose for our basic interior firefighting handline a good-quality, low-presssure combination nozzle that flows 150 gpm at 75 psi. We feel this nozzle gives us everything we desire–maneuverability, the gpm, and a wide range of functions.

But, in the final analysis, the choice is yours based on your local characteristics. While there are advantages and disadvantages to every method or tool, keep in sight the overriding objective: to achieve the critical rate of flow as quickly as possible to knock down the fire. For direct attack on structure fires, both a smooth-bore nozzle and combination nozzle set on a straight-stream pattern will get the job done, provided all other tactical and procedural conditions are met. n

ANDREW O`DONNELL is a district chief and 30-year veteran of the Chicago (IL) Fire Department, currently serving as director of training. He serves on several committees with the Illinois Fire Service Institute, the Illinois State Fire Marshal`s Office, the Illinois Fire Chiefs Association, and the International Fire Service Training Association.

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