TFT - Nozzle Dreams

AUTOMATIC NOZZLES

Part 3: The Water Supply Is Never The Same

By Larry H. Stevens

Editor's Note: This is the third and final installment on nozzles. In this issue we look at water supply and demand and how the correct nozzle can do work better.

The problem of which nozzle is as old as the fire service itself. Odds are, the same arguments were made about fire bucket size in the days of the bucket brigade. They still go on today in the form of which size tanker and what size drop tank. Which tip should be stored on the line for operations off tank water? Which tip is best for the bad water system on the west side of town? Which tip is best for the high pressure water system on the east side of town? Which tip should be used for tanker shuttle operations?

Could the nozzle you choose make the firefighter’s and the engineer’s job easier? Does it matter what style nozzle you use as long as it all gets down to a trained engineer and nozzleman? We have all been told you get more reach and better penetration with a smooth bore tip. No one on this planet can prove it or demonstrate it on the drill or fireground or in a laboratory, though, because it isn’t true.

The facts are physics, and that idea doesn’t compute. We have all been told that you’ll steam the crew with a fog tip, but not with a smooth-bore tip. Either nozzle in the straight stream position will not produce any significant amount of steam. Every time I’m involved in a discussion on which tip is the best, I ask the caller to look out their window and tell me how many fires they can see burning in their community. The answer is always none. Ford or Chevy?

For a lot of departments this argument was solved with the introduction of the automatic nozzle in the ‘70s. For the first time, a fire officer invented a nozzle--often called a thinking nozzle, all of the nozzles in one bag, an intelligent nozzle, or the engineer’s best friend. Like all other nozzles it was more than a nozzle, it was an entire concept. The concept included the new 1 3/4" and 2" attack lines.

For decades the fire service had a nozzle for 3/4" and 1" booster line or forestry hose. Each nozzle had one, two, four or even six flow settings. The 1 1/2" and
2 1/2" lines each had one, two or four flow settings. The 2 1/2" line also had at least three and sometimes five smooth-bore tip options. The fixed and portable master streams had one, three or four fog tip options and three to eight smooth-bore options. Sound unworkable? It was and still is in many areas. Good enough became the word of the day for tip selection. (See Table 1.)

Table 1

Booster Tip	Handline Tips	Master Stream Tip
	1 1/2", 1 3/4", 2", 2 1/2", 3" attack lines
10, 12, 20, 23, 30 10-70 gpm	30, 40, 60, 90, 95, 100, 125, 130, 150, 175, 200, 225, 250, 275, 300 gpm	350, 500, 750, 1000, 1,250, 2000 gpm
	15/16", 1 ", 1 1/8", 1 1/4" tip	1 1/4", 1 3/8", 1 1/2", 1 5/8" 1 3/4", 2", 2 1/8", 2 1/4", 2 1/2", 3" tips
10-125 gpm automatic nozzle	50-350 gpm automatic nozzle	150-2000 gpm automatic nozzle

It is hard to believe that many departments never bought the same nozzle two times in a row. With over 64 nozzle flow options on a single engine, it is a wonder the correct nozzle was ever used. Sadly, in many cases it wasn’t and still isn’t.

The automatic tip offered one nozzle to replace all booster tip flow ranges in one package. It had a flow range as wide as 10 gpm to 125 gpm. The collection of 1 1/2" nozzles could be replaced by one nozzle with a flow range as wide as 50 gpm to 350 gpm. The 1 3/4" and 2" lines could use the same nozzle used on the 1 1/2" hose with the 50 to 350 flow range. 2 1/2" and 3" nozzles could be replaced with the same nozzle used on 1 1/2", 1 3/4", and 2" hose. In fact, many departments only own use one style automatic nozzle for all hand lines.

The Insurance Services Office allows the automatic to count as smooth bore tips and fog tips in both the 1 1/2" and 2 1/2" calibers. Master streams could be replaced with a wide high- or low-flow master stream option from 150 gpm to 2,000 gpm.

Why change? Why go to an automatic? Few fire departments, if any, have a certain water supply on all fires. On the everyday fire, the attack is made off tank water and then is transitioned to hydrant supply. Every fire truck has a different tank-to-pump flow rate that during initial water tank operations probably will not supply everything you want to do. When the engineer switches over to hydrant supply, the water supply can be more or less than what the water tank provided. The length of the supply line, its diameter and the wide variations in flows and pressures found in every water system ensure there are no constants. If this wasn’t so there wouldn’t be stacked tips or nozzles with flow rings.

Take for example an engine arriving at a fully involved warehouse with exposures threatened on one side. The officer might order the deck gun in use off tank water. According to NFPA standards, apparatus of the ‘70s and early ‘80s only had a tank-to-pump flow of only 250 gpm. What tip would you use on the gun? You can’t use the nozzle with the flow ring because its lowest setting is 350 gpm. If you did, you would end up with a 100 psi tip only supplied with 50 psi and a 50 foot reach. This is not the time for a weak stream. The stream will be even weaker if you leave the nozzle set at 500 gpm, 750 gpm or 1,000 gpm. Odds are, the ring hasn’t been turned for a few years, and it won’t turn the day of the fire.

If your department bought fixed-flow master stream tips with 500 gpm, 750 gpm or 1,000 gpm settings, you should just be glad, it isn’t your house exposed by the fire. A three-high stacked tip starts at 1 1/2" and ends at 2" so you end up with a 14 psi stream. A four-high stacked tip that starts with a 1 1/4" tip would work great, but if you bought the 1 3/8" tip option, you get a 20 psi stream. If you bought the wrong tip or nozzle, you might need to repaint your rig or you might need to reposition it to save it! Do you really think the engineer knows which tip flows what amount?

Once the supply line is hooked up the equation changes. The ISO and NFPA say hydrants should be rated 20 psi. NFPA and IFSTA say keep 20 psi on your suction gauge. So if you follow the standards, you have zero energy to push the water through your supply line. Let’s say you have a 50 psi hydrant with unlimited supply. If this fire occurred in a residential neighborhood where the standards allow 600’ to 800’ spacing a 2 1/2" supply line will only move 158 gpm, a 3" line will move 272 gpm, two 2 1/2" line will move 316 gpm, a 2 1/2" and a 3" line will move 588 gpm, a 4" line will move 500 gpm and a 5" will move 791 gpm.

If you’re using 2 1/2" supply line, you will need to use a smaller tip than you were running off tank water to keep from running away from the water supply. With 3" or dual 2 1/2" lines you’ll just keep running the same tip. A combination pair or 3" and 2 1/2" lines or 4" supply hose require setting the nozzle at 500 gpm or using a 1 1/2" or 1 3/8" tip respectively.

Will you shut down to change tips in the heat of battle? Would anyone remember to switch flow settings? I have never seen it on the fire ground or in fire service books, magazines or videos. The guy with the fixed flow 500 gpm tip can finally go to work. With the mighty 5" hose, you still won’t be able to use your fixed-flow 1,000 gpm fog tip or the largest tip on your stacked tip, the 2". You’ll have to settle for a 1 3/4" or fixed 750 gpm fog, or you’ll need to switch the flow ring to 750 gpm.

Sounds simple doesn’t it? All of this applies to a portable master stream, ladder pipe, or ladder tower, as well. No wonder the nozzle is always set at the lowest flow setting, and the smallest tip is always attached to the stacked tips. As soon as one of the firefighters pulls an attack line off the rig, you’ve got to change tip sizes or turn flow rings again. Either that or live with lousy streams. When the second-in company snags a hydrant on the same system you’re working off expect a 30- to 50-percent drop in flow in a residential area, according to the standards. It will be time to change tips again. Just how fast is your engineer? Do you expect your nozzle crews to fight fire or fight the nozzle?

This same scenario can play out with hand lines. We’ve all seen a pump operator who couldn’t maintain SOP 150 psi because there wasn’t enough water to go around. Tanker shuttle and rural water supply operations vary even more, requiring you to know exactly which one of your 64 tips needs to be on which line or lines on a minute-by-minute basis. Harder still, you’ll need to change them a lot!

Add a Spring!

What changes with an automatic tip? Well, you still have a fire, and you still have to make do with the lousy water supply but all of your streams will be full-flow hard hitters at 100 psi tip pressure without changing tips and without pump operator intervention. How is that possible? It is the power of a spring.

An automatic nozzle is just a hole with a baffle in it, like any other nozzle except it has a spring attached to the baffle to allow it to open and close. This maintains the proper nozzle pressure of 100 psi no matter how much or how little water is flowing. As we mentioned earlier, the higher the nozzle pressure, the farther the water travels. The automatic nozzle is an infinitely variable version of the nozzle with flow rings but with a much wider flow range. It will always out-reach a properly supplied smooth-bore tip. Plus you have the versatility of a fog tip to protect you from radiant heat.

In this example, the master stream nozzle had to be set to operate at the 250 gpm supply limit from the water tank. The engineer would simply throttle up until he couldn’t increase the pressure anymore. The nozzle would open to the supply provided; 250 gpm and the spring would keep the nozzle pressure constant at 100 psi. When the supply line came in, the nozzle would adjust with the flow. In the case of the 2 1/2" supply line, it would close down to the flow. In the case of every other size hose, it would stay the same or increase in flow to match the water supply. If another company went to work off the same main, the nozzle would instantly back down to the supply provided. If the supply line was pumped by another engine, the nozzle would open to its 1,000-, 1,250- or 2,000-gpm limit or would take whatever you gave it.

When a firefighter pulls an attack line off the engine, the automatic tips balance the available flow and they still have two good streams. One stream would not steal water from the other. If the master stream were shut down, the nozzle would absorb the bump in pressure, and the nozzle would then flow a little more water. The difference caused by the increased pressure on the line becomes more water to the nozzle minus the higher friction loss in the line. The nozzle pressure stays the same.

When several attack lines of the same or different lengths are pulled off an engine at the same time, the nozzles balance so you’ll end up with every stream a good one. The engineer can pump the standard SOP pressure or whatever each line needs via a flow meter or pressure gauge reading and hydraulic calculations. If you buy into the entire automatic nozzle concept you should be running only automatics on your rig. From the pump operator’s standpoint you simply pump to one of three limits: 1) a maximum or predetermined pump discharge pressure of 200 psi to 300 psi; 2) the rig’s maximum engine rpm; or 3) more often than not the limit of your water supply zero psi to 20 psi on the inlet gauge, until the supply line gets soft or the point just short of cavitation when at draft. The nozzle does all the "thinking," and the engineer just stays within the three limits.

The automatic concept puts control of water supply in the hands of the firefighter at the nozzle and out of the hands of the engineer. By pumping just one, two or possibly three engine pressures, depending on the concept you buy into, the nozzleman knows exactly what to expect at all calls. The one-pressure-concept consists of pumping something near 200 psi for 1 1/2" and 1 3/4" lines (165 psi with 2" hose) and allowing the nozzleman or nozzleman to control the flow desired by simply opening the shutoff to the point of need or ability to hold the line. The stream reach should stay the same at any flow, unlike any other style nozzle. When footing improves, another firefighter is available to absorb reaction, or if you wade into more fire than you expected, the valve can be opened fully when needed to provide maximum gpm. The nozzle will adjust to create the perfect stream at any flow or pressure desired. If it still isn’t enough, ask the pump operator to boost the pressure 50 psi. With a fixed-flow nozzle, the nozzle reaction would skyrocket with little increase in flow. With an automatic nozzle, the flow would increase greatly and the reaction would increase only slightly.

The two-pressure- and three-pressure-concepts are similar. One pressure is for fire attack and one is used for overhaul or insignificant fires (125 psi). The third setting would be a "war" setting for fires where you want everything the nozzle and line are capable of. That would be a 225 psi to 300 psi setting for the "big one." The original concept for 1 3/4" and 2" hose was to replace 2 1/2" for interior attack. It can, if you pump it properly and use a high-flow nozzle or an automatic tip. The grandpa new all about the pressure to flow relationship. Somehow it has been lost by many in the new generation.

The big change offered by automatics is that you don’t need to change nozzles like smooth bores with increases or decreases in water supply. You don’t change tips like fixed flows or have to work within the limits of the tip because the automatic can grow with the flow. You also don’t need to worry about the position of the flow rings or having the flow go beyond the capability of the nozzle.

Automatics can adjust to even difficult water supply situations and do things other nozzles cannot do. That is why they are standard equipment on all ladder pipes, water tower apparatus and platform tips per NFPA standards. Almost all fire apparatus have pressure relief valves to assist the engineer in a difficult job. The automatic nozzle is just another automatic system to make the firefighter’s job easier. According to NFPA standards, all pumper suctions must have pressure relief, as well as all aerial waterways. The power of a spring is the well-respected answer to a majority of our water supply problems.

Can’t Tell What You’re Flowing?

For years instructors have taught that the extreme danger with an automatic is that you can’t tell what you’re flowing. The line will be hard and you’ll have 100 pounds at the nozzle, but you could be flowing 50 gpm and the nozzleman will never know it. That is absolutely true.

If the nozzleman has never held a hoseline before and your department never squirts water, the fire will be the place that you do your experimenting. The fact is that reaction from an automatic is the same as a smooth bore or fixed flow or suicide knob equipped nozzle. If you don’t feel any reaction, you’re not flowing any water!

The problem is not unique to automatics. Since when have the operators of other nozzles been able to tell what they were flowing? Reading the flow ring or knowing the flow rating of the tip means absolutely nothing. The engineer has to be in on the program, pumping the correct pressure. Task Force Tips made a gadget called a Sho Flo that amazed firefighters across America. For the first time they could see at the nozzle what they were really flowing, and it wasn’t as high as they had thought. Using a flow meter could bring the nozzle user to the same conclusion. The answer was simple--throttle up. In other cases the low-bid hose that departments had bought couldn’t flow what the better hose was capable of flowing.

Magic

When someone shows you a new nozzle that flows more than the other person’s nozzle at the same pump pressure, just remember the laws of physics. There is no magic. If the pump pressure is the same, ask these questions to determine why it is really flowing more:

* Is the flow coming off a smaller discharge port!or through more plumbing?
* Are both lines the same length and diameter? Are they the same make of hose?
* Does the nozzle have a larger orifice?
* Is the nozzle operating at a lower nozzle pressure?
* How would you measure nozzle pressure on a fog nozzle? Use a Pitot tube a foot or so from the tip.
* Did your buddy stuff a gasket in your line?
* Is the higher flowing nozzle in flush?

My Nozzle Sucks

Have you ever noticed fighting a liquid petroleum Christmas tree fire that some nozzle styles actually draw the gas and flame to the nozzleman? Use surveyor tape to attach the nozzle to a pole. Advance the pole with a selection of nozzles set in wide fog, and see how many of your nozzles suck the ribbon toward the nozzle. How many of your nozzles blow it away? Ask your firefighters which one they think makes the most sense.

Here we are going into the next century, and old ideas are considered new. We read about special 200-gpm truss lines that are a direct contradiction to the fire flow requirements of all the building codes and couldn’t possibly knock down a vertical lumberyard void space. We see fantastic demos and read about unbelievable flows. At the end of the day, you still need to learn how to pump, hold and advance the line and nozzle combination that best addresses your community’s risks. This contribution needs to be capable of flowing Class A or B foam and should be able to make low- and medium-expansion versions of each. It must also work with your foam proportioner. Clip-on foam tips are an advantage. Skimping on any of these and going for easy will just result in higher fire losses. Remember, although every nozzle is fighting fire somewhere, it might not be the right nozzle!

Larry H. Stevens is the editor of Fire-Rescue Magazine.

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