Saving Lives & Protecting Property
Combination nozzles are the standard for structural and industrial firefighting. They move from a straight stream to a fog pattern by rotating the bumper, and the teeth on that bumper determine the shape of the fog pattern your crew is working with. That one detail affects which tactics are available to you.
Most combination nozzles use one of three tooth configurations: fixed molded rubber, fixed cut metal, or spinning metal. The first two work the same way tactically. The third is a fundamentally different tool. Understanding how they differ will help your department make a more deliberate choice when choosing a firefighting nozzle.
Before getting into the types, it helps to understand what the teeth are doing. As the bumper rotates toward fog positions, the teeth intercept and redirect the water flow. The angle, position, and movement of those teeth determine the geometry of the pattern — how wide it is, how dense it is, and where the water is concentrated.
The most important operational question: is the pattern fully filled, or hollow in the middle?
Both fixed rubber and fixed cut metal teeth work on the same principle. They are stationary elements built into the bumper. Rather than throwing water to the outer edge of the pattern, they direct flow toward the central core, creating a fog pattern that is dense and fully filled from the inside out.
Fixed Molded Rubber Teeth
Molded rubber teeth are the most common fixed configuration. These teeth are molded directly into the bumper and bonded to a metal shaper underneath. Key characteristics:
Fixed Cut Metal Teeth
For fixed cut metal teeth, the teeth are machined directly from the front bumper metal. You get the same fully filled pattern as molded rubber, with one difference: on some designs, rotating the bumper further open transitions the pattern into a wider, flatter shape. This gives cut metal designs a degree of additional versatility.
The fully filled pattern pushes outward ahead of the nozzle. Heat, flame, and smoke are driven away from the crew as the line advances. This creates two important tactical advantages:
When a nozzle with fixed teeth is used in a fog pattern at a doorway or opening, it acts as a hydraulic fan. The filled pattern creates positive pressure that displaces smoke ahead of it. This is the foundation of hydraulic ventilation tactics. A hollow pattern does not create the same unidirectional air movement and cannot be used this way. (TFT)
The fully filled fog pattern creates a moving buffer of water between your crew and the fire environment as you advance. Heat and smoke are pushed forward, not back toward the team.
Spinning metal teeth work differently. They sit on the bumper and are free to rotate. As the nozzle opens toward wider pattern positions, water flow causes the teeth to spin. That spinning action disperses water to the outer edge of the pattern rather than concentrating it in the core. (FireRescue1)
The result is a wide, consistent fog pattern with a hollow center. Water is concentrated in the outer ring, not distributed throughout.
The spinning action also creates finely atomized droplets, which maximizes heat absorption and steam conversion. This makes spinning teeth effective for knockdown and exposure protection in specific scenarios.
A note on tooth material: Stainless steel is strongly preferred over plastic. The spinning motion subjects teeth to repetitive stress and debris exposure. When teeth are broken or missing, the remaining teeth still spin, but the gaps create inconsistencies in the pattern that reduce coverage and can expose the crew to heat. Per NFPA 1962, nozzles with broken teeth should be immediately repaired or replaced. Most manufacturers recommend replacement when more than one-quarter of the teeth are damaged or missing.
The wide hollow pattern has a specialized application that surprises many departments: industrial fire protection where the fire must be kept burning.
Consider a liquefied petroleum gas (LPG) leak that has ignited. In some scenarios, extinguishing the flame before isolating the gas supply would create a more dangerous situation — an unburned, uncontrolled fuel release. The response is to:
Spinning teeth nozzles are well-suited for this. The wide, fine-droplet pattern provides radiant heat shielding without delivering the concentrated flow that would suppress the flame. Because extinguishment is not the goal, the hollow center is not a liability.
This is common in refineries, chemical plants, and LPG storage facilities, where fire brigades train specifically for controlled approaches to valves, shutoffs, and isolation points under live fire conditions.
|
|
Fixed Rubber / Fixed Cut Metal
|
Spinning Metal
|
|---|---|---|
|
Pattern |
Fully filled, fog cone |
Wide fog, hollow in center |
|
Air movement |
Pushes ahead — effective for hydraulic ventilation |
Does not push air effectively |
|
Interior advance |
Drives heat and smoke forward as you push in |
Hollow center can draw heat and smoke back toward crew |
|
Knockdown |
Filled fog pattern provides water coverage across the fire area |
Fine droplets excel at heat absorption and steam conversion |
|
Industrial approach (no extinguishment) |
Not ideal |
Well-suited — wide pattern shields on approach |
|
Durability / maintenance |
No moving parts in tooth assembly; inspect full nozzle per NFPA 1962 |
Spinning teeth require regular inspection per NFPA 1962 |
If your department runs nozzles with different tooth configurations, be deliberate about which nozzle goes where — and train crews to recognize the difference by feel and by reading the equipment.
TFT offers both configurations across its nozzle lineup — including the G-Force, QuadraFog, ThunderFog, Metro, and Mid-Matic — because neither configuration is universally superior. The right choice depends on your response environment, your primary tactics, and the conditions you train for.
For help selecting the right nozzle configuration for your department’s needs, contact a TFT dealer or book a demo.