Choosing a Handline Nozzle
The nozzle is an important part of the firefighting system. The selection of the nozzle to be used by the department should depend upon the tactics and performance required. You should decide what you want your nozzle to do before making your decision.
What Nozzles Do
Nozzles are designed to help put out fires by getting the right amount of water, in the right form, in the right place.
Nozzles have three main functions:
1. Control Flow
The size of the orifice in the outlet of the nozzle controls the flow.
2. Provide Reach
The nozzle creates a restriction at the end of the waterway, which changes water pressure to velocity. Velocity provides the reach, which is necessary to get the water to where it is needed.
3. Create Shape
Different situations require different methods of applying water or foam. Some situations require the reach and penetration of a straight stream, while others require the heat adsorption capability or radiant heat protection of a wide angle fog spray.
There are five basic nozzle types:
1) the solid bore
2) the single gallonage (sometimes called variable pressure/variable flow)
3) the adjustable gallonage
4) the automatic or constant pressure
5.) Multi-Purpose Nozzle (combination solid bore and fog).
Of the five, the latter four make up a group of nozzles commonly called combination nozzles because they produce both a straight and a fog stream.
Solid Bore Nozzle
The solid or smooth bore nozzle is the most basic of the four nozzle types, both in design and function. Its purpose is to produce a solid stream, which provides maximum reach and penetration.
Single (Fixed, or Variable Pressure/ Variable Flow) Gallonage Nozzle
The single gallonage nozzle, the simplest form of the combination or fog nozzle, provides flow at a predetermined rate that cannot be altered significantly while in use. However, when the nozzle pressure is varied the flow varies. Some of today's single gallonage nozzles can provide quality patterns even at reduced nozzle pressures.
Adjustable Gallonage Nozzle
Today’s adjustable gallonage nozzles allow the nozzle operator to manually select a desired gallonage without shutting down. Like the single gallonage nozzle, some of today’s adjustable gallonage nozzles can provide quality patterns even at reduced nozzle pressures.
Automatic (Constant Pressure) Nozzle
An automatic nozzle is designed to maintain a relatively constant pressure over a wide range of flows. This is accomplished by a mechanism in the nozzle that automatically adjusts to an increase or decrease in flow to maintain pressure, and thus reach, fairly consistent. However, these nozzles can give you consistent reach while sacrificing flow.
A combination solid bore and fog nozzle, provides maximum reach and penetration, while still providing the benefits of a fog stream as the situation dictates. This versatile nozzle has the ability for large flows at reduced pressures, and is well suited for multiple applications: interior, exterior, and high rise attacks, CAFS systems, foam applications, direct and indirect attacks, cooling, protection, and ventilation.
Selecting a Nozzle
When selecting a nozzle it is important to choose the type that is best suited for your applications. The following guidelines will help you determine which type and size of nozzle is best for you.
1. What flow range is required?
A nozzle cannot create flow. The available water, pump capacity, hose lays, etc., determine what a nozzle can achieve. The system needs to be analyzed to determine what flow range can be achieved. Determine the maximum flow rate that can be achieved with normal engine pressures and hose lays. Determine the minimum flow that will be required. Consider whether the nozzle will always be used on the same hose or whether it will be used in other applications, which might require different flows.
2. How much flow can be controlled by the available manpower?
Reaction force is determined by the GPM flow, nozzle pressure and pattern. First determine the maximum flow that can be controlled by the available manpower.
3. Are different patterns required?
Decide whether a solid bore nozzle or fog/straight stream nozzle is required. Quality fog nozzles produce almost as good a straight stream as a solid bore nozzle but do require a higher inlet pressure. The reach of a quality fog nozzle at 100psi is about the same as that of a solid bore nozzle or a multi-purpose nozzle at 50psi. If the lower pressure performance of a solid bore nozzle combined with the patterns of a fog/straight stream nozzle would accommodate your needs best, consider a multi-purpose or break apart fog nozzle with the compact solid bore tip. Fog nozzles are designed to provide a dispersed stream to protect personnel. Teeth are provided to break up the water into smaller droplets for better heat absorption and steam effect. Spinning teeth provide excellent breakup of water for heat absorption and steam conversion, due to the elimination of fingering, which is especially important in LPG type fires.
4. Who should control the flow - the nozzle operator or the pump operator?
Determine whether it is necessary to change the flow rate while operating. If so, decide whether the nozzle operator or the pump operator should control the flow rate. If the nozzle operator should control the flow rate, an adjustable gallonage nozzle could be the best choice. If the pump operator is to control the flow rate, a single gallonage (fixed, or variable pressure/variable flow), an automatic nozzle or a multipurpose nozzle would probably be the best.
5. How durable should the nozzle be?
Nozzles are designed to withstand reasonably tough service, but some nozzles will withstand more abuse than others. If durability is crucial and maintenance and repair opportunities are limited, a less complex nozzle design might be the best choice because the simplest nozzles are usually the toughest.
6. What is the level of training?
Departments provide various amounts of training for the pump operator and the nozzle operator. The nozzle should complement the training. Solid bore nozzles require the least amount of training for the pump operator and the nozzle operator. The engine pressure depends mainly on the length and size of hose. Single gallonage or variable pressure/variable flow nozzles require somewhat more training than the solid bore nozzle. Adjustable gallonage fog nozzles require additional training of the pump operator and the nozzle operator because different engine pressures will be required for each of the flow settings with different lengths and sizes of hose. Automatic/constant pressure fog nozzles also require additional training of the pump operator and the nozzle operator. The pump operator must be trained to accurately control the engine pressure and flow with different lengths and sizes of hoses and different operating conditions. Multi-Purpose nozzles require additional training for the nozzle operator, because they must be trained to use the different types of streams, that they provide.
After analyzing a departments needs and considering the strengths and purposes of each nozzle, decision makers will be better prepared to choose how to spend their limited resources on the right combination of nozzles.