How to buy fire suppression nozzles
A nozzle is one component in a water-delivery system; know the system and how each nozzle's attributes fit into it
Is there anything more basic and fundamentally needed on the end of a hose line (besides the operating firefighter) than a good and dependable nozzle? The answer to that question is easily a resounding "No."
After that, however, things get a bit stickier when we look at what's a good and dependable nozzle for fire suppression.
Since the early days of firefighting in North America, the smooth-bore, solid-stream nozzle — or straight-tip nozzle — has been a reliable standby for many fire departments and continues to be to the current day.
A new kid arrived on the block when Dr. John Oyston was granted the first U.S. patent for a fog nozzle. That kicked off a considerable amount of research worldwide in the 1920s on the effects of fire behavior and spray streams for interior fire attack.
History lesson aside, how should a newly appointed fire chief at a small- to medium-size department approach buying the right nozzle?
"The selection of a hand line nozzle should depend upon the training, tactics and performance required," said Andrea Russell, global product manager at Akron Brass. "A department should decide what they want and need their nozzles to do before specifying."
Task Force Tips Chief Marketing Officer Rod Carringer agrees.
"First, be clear on the target fire flows you expect your suppression teams to deliver," Carringer said. "We see many agencies striving to achieve a minimum of 150 to 175 gpm on initial attack handlines. And before any nozzle choice is made, the volume of water needed for suppression is a critical decision that needs to be determined."
He also said it is important to look at the entire delivery system and test all aspects to ensure that target fire flows can be met.
"This includes, hose size and length, desired pump discharge pressure, water supply capabilities and hose handling characteristics," he said. "Nozzles are just a small part of the overall delivery system."
Russell and Carringer said to invite distributor and manufacturer representatives to do flow demonstrations with their nozzles. This will allow firefighters and officers to ask questions and get their hands on the various types of nozzles to find out what the department needs and wants.
"Put it through its paces with your hose, your engine pressures, and with your team," Carringer said.
Russell emphasized the importance of ensuring that the nozzle manufacturer stands behind its products by offering after-sale service and a warranty.
Today there are many nozzles from which fire departments can choose. The major categories of nozzles include solid-bore, fixed-orifice, adjustable gallonage, and multi-purpose.
The solid-bore, or straight-tip, nozzle has a solid stream with a fixed flow rate and provides good reach and penetration with minimal steam conversion. They're very durable with minimal required maintenance.
Solid-bore nozzles are typically specified to operate at nozzle pressure of 50 psi, which creates less nozzle reaction for the firefighter on the knob. Pressure and flow control is with the pump operator.
The fixed-orifice nozzle is specified for a fixed pressure and flow. Fixed-orifice nozzles can be specified with both straight stream and adjustable fog patterns capabilities.
When operated at its specified nozzle pressure of 100 psi, this nozzle provides both reach and penetration when used in the straight stream mode. It provides heat absorption, personal protection and hydraulic ventilation capabilities with the fog pattern settings.
Fixed-orifice nozzles are characterized by low maintenance, no flow control and require a minimum of initial nozzle training. Pressure and flow control is with the pump operator.
The adjustable-gallonage nozzle can deliver a straight stream, an adjustable fog pattern and has adjustable flow-rate capabilities when operated at its specified nozzle pressure, typically 100 psi.
Like the fixed-orifice nozzle, this nozzle provides reach and penetration with the straight stream and heat absorption, personal protection and hydraulic ventilation with the fog patterns. The nozzle requires a moderate degree of maintenance and training.
The adjustable-gallonage nozzle gives the nozzle operator the ability to increase or decrease their desired flow rate at the nozzle, provided that the pump operator maintains 100-psi nozzle pressure.
The multi-purpose nozzle is a true smooth-bore nozzle with an adjustable fog pattern that can change between solid stream and fog without shutting down.
This nozzle provides reach and penetration with the straight stream and heat absorption, personal protection and hydraulic ventilation with the fog patterns. While it is durable and needs moderate maintenance, good training is required for both line firefighters and pump operators.
Over 25 years ago the automatic nozzle was invented to maintain reach when water supplies were reduced. This was accomplished by squeezing off the flow within the nozzle using dependable spring, connected to the baffle that forms the discharge orifice in order to build pressure.
The nozzle gained much popularity when departments were willing to trade flow for reach because they didn't have a better option.
With recent advancements in nozzle technology, that is no longer the case. The stream quality and higher flows at reduced pressures provided by these new nozzle designs and construction no longer sacrifice flow to achieve adequate reach.
A nozzle doesn't create flow, it provides shape and velocity to the water stream. The available water, pump capacity, hose lays, hose size and friction loss determine what a nozzle can achieve.
Any fire department's system needs to be analyzed to determine what flow ranges are possible. The following are guidelines to use in analyzing flow needs.
- Determine the maximum flow rate than can be achieved with normal pressures and hose lays, taking into account friction loss and other constraints.
- Determine the minimum flow required.
- Consider if the nozzle will always be used on the same hose or if it will be used in other applications requiring different flows.
- Determine what nozzle reaction force is acceptable based on the available staffing.
- Decide what level of training firefighters will receive.
- Consider all operational tactics the department uses.
- Consider what stream patterns make the most sense for the department's needs.