In today’s fire service, there are a multitude of nozzles available to firefighters that are capable of delivering various stream types and fire flows. Some have been around a long time, some are better versions of their original design, and some have come on the market in just the past decade.
The most important element for firefighters to remember with regard to nozzles is that the nozzle is your primary weapon. As such, it’s extremely important that you care for it properly; it should be taken care of in the same manner that a soldier would care for their weapon. You should have a thorough understanding of its operation, maintenance requirements, downfalls, safety concerns, flow rates, reaction forces and any special features. Without this understanding, your knowledge base about your nozzle would essentially equal that of a civilian.
Nozzle Considerations & Testing
When selecting a nozzle, make sure you fully understand its capabilities with your current system. Whether it’s a nozzle you’ve had for 15 years or a new nozzle someone is trying to sell you, put the nozzle on your standard hose load and, with a digital gpm gauge, perform flow testing to ensure you get adequate water. Also consider reach, penetration and reaction force on the firefighter. The only way to truly know what you’re getting with a nozzle is to do formalized testing. (For more on conducting flow tests on hoses and nozzles see “Water Works: Make sure your hoselines can flow the required gpm for your response area,” April 2010 issue.)
When using any nozzle to extinguish a fire, keep in mind that actual flow may be affected by many variables, such as differences in piping from the pump to the discharge point, increasing friction loss, variances in hose types and their individual friction loss, kinks in the hose, different pump pressures, water supply issues and debris passing through the water system.
Lastly, remember that the nozzle doesn’t matter if water never makes it to the tip, but some nozzles perform far better at low pressure and flow than others. So be sure to test your nozzle under ideal conditions and under poor conditions to determine how it will perform in both good and bad water-flow situations.
Nozzle Types
Today’s nozzles offer a wide variety of features, characteristics and uses. The key is determining which nozzle is right for your needs. To help you make that determination, here’s a breakdown of some of the basic nozzle types, and the pros and cons of each.
Smooth-bore
The smooth-bore nozzle, which has been around for many years, could be considered the staple of the American fire service. Typically, the smooth-bore nozzle produces the greatest reach/gpm combination of all nozzles while at the same time using the lowest engine pump pressures.
The smooth-bore will also maintain the same water pattern to reach the seat of the fire, keeping the pattern compact and getting large amounts of water at the seat of the fire. One drawback is that unless the water pattern is broken up, the water from a smooth-bore won’t absorb as much heat as its broken or fog-stream counterparts.
Pros:
- Lowest cost
- Multiple sizes for desired gpm flow
- Good reach, penetration
- Low engine pressure requirements
- Easily passes debris
- No moving parts
- Simple to use and operate
- Low reaction force
Cons:
- Pattern must be broken by nozzle movement to increase heat absorption
- Non-variable stream
- Poor foam production performance
- Poor hydraulic ventilation performance
Fixed-gpm/Variable Stream/Constant Flow
This type of nozzle will produce the predetermined gpm when supplied with the required nozzle pressure. For example, a 50-psi/250-gpm nozzle produces 250 gpm when supplied with 50 psi of nozzle pressure. Simply put, you get what the manufacturer says you’ll get at the required nozzle pressure, similar to its smooth-bore counterpart.
Years ago, these nozzles only came in 100-psi versions, but now you can find them with common nozzle pressures of 50, 75 or 100 psi. Another commonality between these nozzles and the smooth-bore: You can get more water with more nozzle pressure, but you’ll also experience more nozzle reaction. These nozzles provide excellent flow and mobility, as well as the flexibility of a variable pattern.
Pros
- Variable stream (straight, narrow fog or wide fog)
- Decent foam production
- Decent reach
- Low-pressure versions produce less nozzle reaction, less engine wear
- Rugged
- Easy to use
- Costs less than other versions (variable gpm and automatic)
Cons
- Can’t pass debris easily
- Moving parts inside nozzle, which may lead to mechanical failure, water deposit build-up changing operation
- High-pressure versions can have poor flow at low pressure
- Larger, bulkier and heavier than smooth-bore counterpart
Automatic Variable Flow & Stream
The automatic variable flow nozzles are very common in the fire service; however, only two of the big three nozzle manufacturers currently make an automatic nozzle. The nozzle features an internal spring mechanism that’s pre-set at the factory, which provides a pretty constant nozzle pressure at varying gpm.
Two main issues with automatic nozzles: 1) they’ll shut off at low pressure and 2) they seem to always provide what appears to be an adequate stream even when gpm is low. The automatic nozzle may produce what appears to be a penetrating stream with extended reach; however, at lower nozzle pressures, this stream may produce well below 100 gpm.
We found that many older automatic nozzles generally require higher nozzle pressures to deliver water in sufficient quantities for an interior attack. In standardized testing, we determined that all of our old automatic nozzles flowed different gpm flows while engine pressure, hose size/length and nozzle pressure remained constant. After doing a little research, we determined that many of our automatic nozzles were old and hadn’t received annual calibration maintenance as prescribed by the manufacturer. We also found that the nozzle won’t operate or could even shut off at low nozzle pressure without warning.
In addition, automatic nozzles must be pumped appropriately and used as they are designed in order to get the desired gpm. They are different animals, so to speak, and therefore must be fully understood by their users.
Pros
- Variable stream (straight, narrow fog or wide fog)
- Good foam production
- Decent reach
- Rugged and easy to use
- Constant nozzle pressure
Cons
- Most expensive
- Varying gpm without regular maintenance
- Good stream production even at low gpm
- Will shut off or may not open at low nozzle pressures
- Poor flow at low nozzle pressure
- Larger, bulkier and heavier than smooth-bore counterpart
Broken or Aspirated Stream
The broken or aspirated stream nozzle provides great mobility and excellent gpm flow at low nozzle pressures. The most common version of this nozzle, the Vindicator, is made by First Strike Technologies. It’s larger than other nozzles and aspirates the stream as it travels through the tip, producing large water droplets to better absorb heat. This nozzle is also good for use with foam applications, as it self-aspirates the foam at the tip. The drawbacks when compared to smooth-bore or variable-stream nozzles: reach and penetration.
Pros
- High gpm at low nozzle pressure
- High heat absorption
- Minimal back pressure or reaction force
Cons
- Cost
- Non-variable stream
- Larger, bulkier and heavier than smooth bore counterparts
Important: Despite some of these nozzle types being around for decades, formalized training is a must for all. Why? A firefighter who routinely uses a combination nozzle won’t be able to transition to a smooth-bore without it–this is especially true of the Vindicator.
Which Is Best?
This question goes around the fire service and fire departments all the time. Often, people don’t care what they use, so they use what’s provided to them under the parameters that they’re given and don’t spend too much time looking into how to make their flow better or all that’s available.
The bottom line: No one can tell you what to use. Each nozzle has its pros and cons; selection can vary geographically. Our advice is to flow test your current nozzles and try to get as much water as possible while taking into consideration reaction force and maneuverability. Remember to do this while in an attack position from the ground, not while standing up. Your goal, with whatever system you have, is to deliver as much water as possible. If you aren’t happy with your system or flows acquired, try to evaluate other systems so you can change the minds of the decision-makers in your organization. Sometimes, a simple comparison of flows with a gpm gauge is all you need.
Things to Remember
Test your own nozzles with a properly calibrated gpm meter and your pump and hose systems on a regular basis. Always test new nozzles before purchasing them from an over-eager salesman. Ensure you clean and maintain your nozzles as outlined in the manufacturers’ directions to ensure proper operation and use. Above all else, keep in mind that the nozzle is your primary weapon to suppress fire. Care for it just as a soldier cares for their weapon.
