Firefighting Water Flow

9 Common Questions, If You’re Considering an Automatic Firefighting Nozzle

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Date January 13, 2022
Date January 13, 2022
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Automatic nozzles are a relatively new technology to the firefighting scene, compared to traditional fixed flow or selectable nozzles.

You’ve probably heard at least one of the following about automatic nozzles…

  • “You can’t tell what you’re flowing, if you’re using an automatic nozzle.”

  • “Automatic nozzles need calibrated and it’s a PITA to make sure they’re right.”

  • “Automatic nozzles are a gimmick and they don’t offer a real advantage to fixed flow or selectable nozzles.”

We’re going to talk about each one of these points right here as well as a couple others. If you have more questions, we’d love to answer them or setup a demo to make sure you make the right decision for your specific firefighting needs so you’re confident your crew has the equipment they need to stay safe and go home to their loved ones every day.

 
  1. If the stream looks “good” no matter the flow rate, how do you know what you’re flowing?

  2. Do you need a flow meter if you’re using an automatic nozzle?

  3. Why does the stream look “good” even at low flow rates? 

  4. Will your firefighters think they’re delivering proper flow rates when they’re not? 

  5. Do you have to calibrate automatic nozzles?

  6. How does an automatic nozzle work?

  7. Why do automatic nozzles have so many extra parts?

  8. Why is an automatic firefighting nozzle more expensive than a fixed or a selectable nozzle?

  9. Why would you need an automatic nozzle?

 
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If the stream looks “good” no matter what the flow rate, how do I know what I’m flowing with an automatic nozzle?

Unless you have an extreme and uncharacteristically high level of intuition, you likely don’t know with absolute certainty what you’re flowing out of fixed, selectable, or automatic nozzles. However, if you have the proper tools, training, and a great team you can operate with all the confidence in the world. Knowing your flow seems to be a timeless question in the fire service.

How do you know your flow?

Calculating flow while using an automatic nozzle is the same as any other nozzle and represented with the equation Pump Discharge Pressure = Friction Loss + Nozzle Pressure (PDP = FL + NP). Ok, now that we have your eye rolls after we mentioned the PDP equation that’s been beat into your head no less than a million times during training classes, let’s move on to an easier method of quantifying your flow rate – a flow meter.

A properly utilized flow meter is one of the most valuable tools for training, testing, and it’s a no BS way to know your flow with an exceptional amount of certainty! It’s a no-brainer investment that gives you an objective measure of GPM that you’re delivering from the specific equipment your department uses on the front line. No matter what nozzle you are using, a flow meter is likely the only tool that will provide you with the actual gallonage you are delivering at any given time. It removes the manual calculation, forgoes any unforeseen parameters that aren’t being accounted for, and quickly provides you with actionable insight into your operations ability to meet the requirements demanded by the fire ground attack you are launching.

So, you’re saying I need a flow meter if I’m using an automatic nozzle?

You might need or want a flow meter as detailed above. However, you should NEVER neglect your basic senses of sight and feel you’ve developed from years in fire service!

Your Sight

The stream of a 150 GPM flow rate is physically larger and bulkier in diameter when compared to a stream with a flow rate of 70 GPM. Great, but you have zero visibility within the fire environment! That’s completely understandable and you’ve probably developed a feel for flow in your years of service.

Your Feel

If you’ve served in the fire service for any amount of time you know that 150 GPM or more has a definite feel to it. The feel we are talking about here is nozzle reaction. 150 GPM has a known reaction force and feel to it no matter what the nozzle’s rated pressure is 50, 75, or 100 psi. Likewise, the nozzle reaction of 70 GPM is like holding a garden hose. You can likely approximate or have a general sense of the fire flow just by the feel with a fixed flow, selectable, or automatic nozzle.

Your Fire Environment

If the environment is not improving, you can either deliver more water to overcome the heat release rate or, you can edit where you’re delivering the water in an attempt target a more effective area of the fire itself.


So, how do you know if you’re delivering enough water in the heat of battle? Training!

 

Why does the stream look “good” even at low flow rates?

The stream of an automatic nozzle looks good even at low flow rates because an automatic nozzle maintains its rated pressure consistently, no matter what the flow rate is. So, you, the firefighter, always get the maximum reach, penetration, and useable stream regardless of flow rate. This ensures the water you are flowing will actually reach your intended target not matter if you’re cooling as you make the push or when you reach the seat of the fire.

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Will my firefighters think they’re delivering proper flow rates when they’re not?

Yes, the stream will, in fact, look “good” even at a low flow rate. However, there are many ways to know if you are actually delivering your targeted flow rate during use.

Key indicators you’re not impacting the immediately dangerous to life and health (IDLH) atmosphere you’re working in:

  • You’re not flowing enough water to overcome the heat release rate of the fire. Your everyday flow rate may still not be enough for the job at hand.

  • You’re not getting the water where it needs to go. The Underwriters Laboratories Fire Safety Institute has proved that, if you get water immediately where it needs to go, it doesn’t take much to put that fire out.


 
 

Do I have to calibrate automatic nozzles?

No. You don’t need to calibrate automatic nozzles. What is paramount is that you inspect your automatic nozzles for obvious signs of damage or malfunction. In fact, ALL nozzles need to be inspected after each use and at least annually regardless of the type of nozzle in question. This is something covered in depth and easily referred to within NFPA 1962: 2018 edition, Section 5.2.1 The key word here is ALL nozzles, no matter the type.

It’s also important to note that every nozzle in service needs to be tested at least as frequently as the hose with which it is used. This reference can be reviewed within the same NFPA edition in Section 5.3. The testing frequency and inspections are completely non-biased for ANY type of nozzle. Just as our brothers and sisters in blue inspect, clean, and service their firearms, so should we as the greater fire service not only check our SCBA’s but, also check our front-line weapons prior to making the push on to the next job we are called to serve.

 

So, how does an automatic nozzle work?

To get a better idea of how an automatic nozzle works, we’ll actually start by looking at set of smooth bore stacked tips.

The New York stack shown includes a 1/2” and a 15/16” smoothbore. How do you flow more water out of this stacked tip combination?

An increase in pump discharge pressure (PDP) will achieve an increased flow rate and that’s consistent with any nozzle. Simply put, you want more flow? Increase your PDP.

However, if the fire you’re facing requires a higher flow rate even after the increase in the PDP, how do you flow more water from this same set of stacked tips? You don’t. In fact, the firefighter has to shut the nozzle down, remove the smaller 1/2” tip then open it back up to use the larger 15/16” tip only. The bigger the opening, the bigger the flow capacity will be. After making that smoothbore tip change, the firefighter will also have to communicate back to the pump operator so the operator can adjust the pressure to make sure the new tip setup is operating properly.

Imagine for a second that you had a handheld nozzle that would do this automatically?

That nozzle exists and it’s called the automatic nozzle!

 

Learn more: How an Automatic Nozzle Works

 

The automatic nozzle has a spring-loaded baffle. When there’s a pump discharge pressure increase, the baffle moves forward to create a larger opening. The more it opens the higher your flow rate. If you decrease the PDP, the baffle moves backwards to create a smaller opening because you are delivering a lower flow rate. This baffle movement ensures that pressure changes, intentional or unintentional, DO NOT affect your ability to reach the target.

Depending on the model of automatic nozzle you’re using, the average mid-range handheld automatic nozzle can have the flow capability of a 15/16”, a 7/8”, and a 1/2” all in a single nozzle! Other high-range automatic nozzles can have the flow capability of a 1-3/16”, 1-1/4”, 1-1/8”, 1”, 15/16”, 7/8”, and 1/2”.

Each nozzle is different and those differences are not necessarily bad. The important thing to remember is how the tool functions. Understanding how your automatic nozzle functions will ensure you pick the best one for the way your department operates and the challenges a particular response district faces.

 

Why would I need an Automatic Nozzle in the First Place?

You may not need it!

Not every department nor every firefighter needs an automatic nozzle, but those who do choose an automatic nozzle should know how they operate, just like any other tool that is used on the fire ground. A type Y nozzle is not necessarily better than type Z nozzle, they’re just different. We’re always looking for the right tool for the right job.

 

Learn more: Choosing the Right Handheld Fire Hose Nozzle for Me


Begin with the end in mind. What is the intended purpose of the nozzle your department is considering purchasing and/or currently using? Obviously, you need to put the fire out. But is it exclusively limited to structure fires?

  • Do you foresee any car fires?

  • Do you ever have to deliver finished foam?

  • What about salvage and overhaul?

  • What is your plan if fire conditions change and you call for more water on your line but there’s no more to give?

  • Do you want to be sure your nozzle is maximizing flow rate at a wide range of available pressures?

  • Are you only concerned with maximizing pressures and rarely encounter low pressure scenarios?

These are questions ONLY you can answer!

An automatic nozzle has a variable flow range at a constant pressure. To be exact, “an adjustable – pattern spray nozzle is one which the pressure remains relatively constant through a range of discharge rates” NFPA 1964:2018, Section 3.3.18.3.

The question then becomes, does your department need that variable gallonage? Are you assigned to an engine that just runs structure fires, so one rated flow at one rated pressure is all you need? On the other hand, do you need or want variable gallonage to cover a wider range of calls you are expecting?

Start with the why and work back from there to determine the best choice for your crew and your needs. If your responses differ and you are on a department that runs to a variety of calls that require variable flow, an automatic is likely going to be able to supply you with the best reach, penetration, and hose line management for the water you need and the job you’re facing.

A jack of all trade’s nozzle. The swiss army knife of nozzles. The crescent wrench nozzle. In the end, you may just need the single blade pocket knife or the individual open-ended wrench for the job. That’s totally ok! It doesn’t make one better or worse, it only makes them different and we’re here to help you choose the right tool for the right job.

 

Why do automatic nozzles have so many extra parts?

Yes, automatic nozzles have more moving parts. They have one more moving part to be exact. The one additional part is the baffle. The spring-loaded baffle moves back and forth depending on your flow rate. It moves forward to make a bigger opening for larger flow rates, and it moves backwards to make a smaller opening for lesser flow rates. The baffle movement ensures that pressure changes, intentional or unintentional, DO NOT affect your ability to reach the target. This advancement in firefighting nozzle technology might seem unnecessary if you have perfect supply or pump pressure. However, that is rarely the case and utilizing automatic nozzles can enhance your crew’s ability to save lives and protect property with a greater level of confidence and safety.

 

Why is an automatic firefighting nozzle more expensive than a fixed or a selectable nozzle?

Automatic nozzles are generally more expensive when compared to fixed or selectable nozzles for the same reason an automatic transmission in a vehicle is more expensive when compared to a manual transmission or why a multi-tool is more expensive than a single blade pocket knife or why an adjustable wrench is more expensive than a individual open-ended wrench. The more expensive solution has more capabilities and options to accomplish a greater variety of jobs at hand. This added capability comes at a cost in research, development, and manufacturing complexity. Is the juice worth the squeeze? Only you can make that decision and each department’s use case(s) will have an influence on the right nozzle choice. Our product experts are always available to help you make the best decision and you’re always welcome to schedule a demonstration so you can try each option our for yourself.

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One of your most important missions is going home safe to your loved ones. It’s firefighters like you that make our team here at Task Force Tips passionate about fire service and first responder innovations. Whichever nozzle your department chooses, we are here to be your trusted source of innovative firefighting equipment and help assist you in saving lives while protecting property.