# Thread: Low Pressure Nozzles

1. ## Low Pressure Nozzles

The department that I am with is looking at new nozzles, and its been a fight the older members still like the turbojets 95gpm @ 100 psi with 1.5" hose. A group of use want to up the gpm to say 150 gpm and switch to 1.75" hose. We have talked to the akron rep. and sent a couple demos Assault 150@50psi and 150@75psi but recommended the 200@100psi. Has anyone got any input on which way to go. and also what brand hose.

2. We use Akron Assaults at 75psi/175gpm.

3. Both my career and volly FD use Elkhart Low pressure nozzles 200 gpm at 75 psi.

I highly recommend going with a low pressure nozzle.

FyredUp

4. One of my past departments used a 50psi /200 gpm breakaway nozzle, I don't remeber who made it. The nozzle worked great, worked as a fog or you could unscrew the end and it gave you a 1" smooth bore.

Nice thing with the 50psi fog nozzles is it makes the engineers job a little easier since it doesn't matter if you have a smooth bore or a fog nozzle on the end, both are 50 psi NP.

I have heard people complain the low pressure nozzles are more prone to getting kinks in the line but I didn't find that to be a problem.

If you really want 200 gpm though you are better off going with a larger diameter hose, you can get 200 gpm out of a 1 3/4" line but it requires a lot more work from the pump. At 150 gpm 1 3/4" requires about 36 psi per 100 feet to overcome the friction loss, at 200 gpm you need 62 psi per 100 feet.
We don't use 2" so I'm not sure of its coefficient but 2 1/2" at 200 gpm only needs 8 psi per 100 feet.

5. another thing is the nozzle reaction force akron has no numbers for the nozzles that are 75 and 50 psi. Does anyone know if there is a formula. The first akron rep said to use a 100psi chart.

Bob

Use this chart to determine the approximate flows from the nozzles you desire to purchase. The 200@100 is a good nozzle because it flows about 140 GPM at 50 PSI and about 170 GPM at 75 PSI tip pressure if used as a low pressure nozzle Its maximum efficient flow is 200 GPM at 100 PSI. This gives you a nozzle that, while stamped 200 GPM @100 PSI is actually also a low pressure fog nozzle. if you "underpump" it.

If you can't sell the dino's on the hose upgrade, you can still get better flowing nozzles and get 150 GPM easily through typical length preconnects especially if you use low pressure nozzles.

7. ## Pros and Cons

Pro

Lower pressure nozzles have less nozzle reaction (about 30% less at 50 psi when the pattern is the same).

The engineer's task is simpler if all nozzles have the same nozzle pressure.

Con

Automatic nozzles work through a nozzle pressure range (not simply a fixed pressure). Low pressure automatics do not work as well at the low end of this range. This is not a big problem if you keep the flow rate up (e.g., 150-200 gpm through a 70-200 mid range automatic).

Kinking can be an issue. We have been using dual pressure automatics for several years and have experienced significantly more kinking in the 50 psi setting. This means your hose teams (and others) need to pay attention to this and chase the kinks out without fail.

Droplet size in the fog pattern gets larger as nozzle pressure gets lower. This has a significant impact on cooling capacity of the fog stream. This is an issue when gas cooling or dealing with a fire under pressure (e.g., propane, or fire being pushed by the wind). There is a photo of this in the thread titled "nozzle reaction"

Thoughts

I would go with 1-3/4" hose for increased flow capability, but stick with 100 psi nozzle pressure for combination nozzles given their better performance (particularly when gas cooling) and reduced tendency to kink.

Having taught hydraulics for over 30 years in both career and volunteer settings, I don't think that the difference in nozzle pressure is as big of a problem for engineers as sometimes is made of it.

Nozzle reaction is a significant issue and probably the biggest strong point for me in favor of lower nozzle pressure. However, with good hose handling technique the nozzle reaction from flow rates up to 200 gpm through 1-3/4" hose is manageable.

Hope that this helps.

Cheers

8. We are in the process of switching to TFT Metro's on our 1 3/4" lines.

http://www.tft.com/newsite/class.asp...GI&gid=2&pid=4

We have the 200 GPM @ 75 PSI disc installed but underpump them a little to flow a minimum of 150 GPM.

Yes, kinking is a problem but it can be overcome by training EVERYBODY to watch for kinks and remove them if found.

We've found the lines much easier to manuever and even our smallest members can easily handle the nozzle while getting a good flow.

9. Originally Posted by obfpd172
The department that I am with is looking at new nozzles, and its been a fight the older members still like the turbojets 95gpm @ 100 psi with 1.5" hose. A group of use want to up the gpm to say 150 gpm and switch to 1.75" hose. We have talked to the akron rep. and sent a couple demos Assault 150@50psi and 150@75psi but recommended the 200@100psi. Has anyone got any input on which way to go. and also what brand hose.
If you are looking for a low pressure nozzle that will reduce reaction force, is affordable, easy to maintain and doesn't clog and will give you 150gpm...that is a increase in volume with a reduction in reaction force...there is only one nozzle that will give you that at a fair price.

Just go with a 15/16th tip. 1 1/2 shut off with or without the pistol grip, what ever you prefer...I suggest NO pistol grip as it promotes poor technique and lazyness.

At a NP of 50 psi it will give you around 180 gpm on a1 3/4 line and will have less reaction force (great for lower staffed depts.). It will provide better penetration and ease of advancement. Both critical to a swift and smooth knockdown.

The pump pressures will be lower thus allowing for greater capacity to be pumped by one Engine before having to take lines off another.

You would want model No. 1440 or 1441

Anyone who tells you to use a 100psi 200 gpm automatic has never advanced one down a hallway and around a bend or two with minimal manpower. It isn't realistic and you will likely not achive that flow on the fireground without extreemly high Pump pressures and the increased danger of the nozzle team of loosing control of the nozzle.

Stop supporting these superfulous Engineers who are trying to reinvent the wheel.

FTM-PTB

PS- I don't work for Akron nor was this a paid endorsement.

10. Originally Posted by FFFRED

Anyone who tells you to use a 100psi 200 gpm automatic has never advanced one down a hallway and around a bend or two with minimal manpower. It isn't realistic and you will likely not achive that flow on the fireground without extreemly high Pump pressures and the increased danger of the nozzle team of loosing control of the nozzle.

Stop supporting these superfulous Engineers who are trying to reinvent the wheel.

FTM-PTB

PS- I don't work for Akron nor was this a paid endorsement.
Akron may as well hire you to market their smooth bore line

I think you assumed the nozzle being discussed was an automatic, it isnt. Akron's 200@100 tip is a fixed gallonage tip marketed under the "assault" line. Same deal as an Elkhart Chief or TFT Metro. Same principle as a smooth bore. One sized opening and the flow is determined by how much is pumped at the panel. Only difference is that it lets you make that dreaded fog stream too!!!

11. Originally Posted by MG3610
Akron may as well hire you to market their smooth bore line

I think you assumed the nozzle being discussed was an automatic, it isnt. Akron's 200@100 tip is a fixed gallonage tip marketed under the "assault" line. Same deal as an Elkhart Chief or TFT Metro. Same principle as a smooth bore. One sized opening and the flow is determined by how much is pumped at the panel. Only difference is that it lets you make that dreaded fog stream too!!!
I assumed you were refering to an auto as I read it you mentioned Autos and never mentioned any other version.

Even with that type nozzle the result is still the same...a rigid almost unmanagable line that has more reaction force than that of a 2 1/2 flowing almost 40% more water. The manuverabilty that is supposed to be a supperior quality and feature of the 1 3/4 line is lost at those pressures.

Don't believe me...use a flowmeter on a handline and advance it up the stairs to the second floor down a hallway, into a bedroom and around a couple of bends...you want 200gpm...you are going to pay for it in mobility and safety (the nozzle team is one slip or stumble away from loosing control of this high pressure line) It was an eye opener when my old dept did it....funny though, the Brass still didn't get it and still haven't changed much.

Either way I would say that based on the qualities he is looking for the smooth bore would be the best choice...but we all know too many out there are still stuck with some misapplied 1950s methodology which only marginally works in labratories and on board ships.

FTM-PTB

12. or, you can get the breakapart and have the best of both worlds available to you.

13. Originally Posted by FFFRED
I assumed you were refering to an auto as I read it you mentioned Autos and never mentioned any other version.

Even with that type nozzle the result is still the same...a rigid almost unmanagable line that has more reaction force than that of a 2 1/2 flowing almost 40% more water. The manuverabilty that is supposed to be a supperior quality and feature of the 1 3/4 line is lost at those pressures.

Don't believe me...use a flowmeter on a handline and advance it up the stairs to the second floor down a hallway, into a bedroom and around a couple of bends...you want 200gpm...you are going to pay for it in mobility and safety (the nozzle team is one slip or stumble away from loosing control of this high pressure line) It was an eye opener when my old dept did it....funny though, the Brass still didn't get it and still haven't changed much.

Either way I would say that based on the qualities he is looking for the smooth bore would be the best choice...but we all know too many out there are still stuck with some misapplied 1950s methodology which only marginally works in labratories and on board ships.

FTM-PTB
I'm thinking you read up to the third word then it read something like "blah....blah..combo..blah..blah...blah...fog...bl ah...."

You will only seem me mention automatics as products endorsed by the devil himself

The 200@100 nozzle in my opinion is an ideal low pressure nozzle that would rarely be used at 200 GPM. You would get about 10 LBS more reaction flowing the equivalent flow (180) as your beloved 15/16" with the 200@100 tip. Just look at the chart I linked in my above post.

FYI, we have 15/16" and 1 1/8" tips on our primary handlines where I work, so i understand the dynamics of these tips.

14. We use 1 3/4 with Elkhart 200gpm @ 75,

2 other things to consider

1) we keep a preconnect 2" with Elkhart low pressure, nice 2nd line as compared to a 2 1/2

2) just purchased saberjet, both smoothbore and fog nozzle combined into one. Works well so far only used twice.

15. Originally Posted by FFFRED

Just go with a 15/16th tip. 1 1/2 shut off with or without the pistol grip, what ever you prefer...I suggest NO pistol grip as it promotes poor technique and lazyness.

.
I agree with most of what you have said. However I can't buy into this part. Having a pistol grip helps to hang on to a hot hose line, or allows you to hang on for a longer period of time.

16. hang on for a longer period of time
Huh? The guy on the nozzle, at least for us, only directs the stream. He may be getting "beat up" by the heat of the fire, but not the hose. The "force" of the hose is being held by the guy in the backup position. Pistol grips make for poor techniques.

17. Originally Posted by fireslayer123
I agree with most of what you have said. However I can't buy into this part. Having a pistol grip helps to hang on to a hot hose line, or allows you to hang on for a longer period of time.
I concur with Bones.

What is a hot hoseline?

Are you telling us that you hold the nozzle like Rambo shoots his M60?

Your statement leads me to believe you are describing the poor technique and bad habits that I mentioned above...and it is obviolusly created by having this pistol grip.

If you can't hold on to the hose with the nozzle out in front of you...you need to get one of these:

Or you need to use that fog tip you are using for a wheel chock and get a smoothbore with less reaction force.

FTM-PTB

18. A department in our automatic aid group won a FEMA grant to upgrade nozzles and hose. They are a small volunteer department that runs few first due fires. To keep everything as easy as possible for the operators they decided on the following:
Akron Assault Low Pressure 150 gpm @ 50 psi adjustible nozzles
Akron 7/8" solid bore nozzles 160 gpm @ 50 psi
Akron 2.5" ball shutoffs and Elkhart 1 1/8" tips for large lines 265 gpm @ 50 psi
All the solid bores have Elkhart stream shapers on them.

Thus, every nozzle pressure is 50 psi regardless of the nozzle choice. They flow more water at lower pressures than the previous 100 psi fog nozzles. They have their choice on the pre-connects of fog or solid bore and the large flows get the same nozzle pressure. Using low pressure nozzles at 75 psi may complicate matters for the pump operators at some point. You could have older nozzles at 100 psi, low pressure at 75 psi and solid bore at 50 psi. It's a matter of remembering which nozzle is on the line that gets the operators in trouble, not the fact that they can compute the flow. Teaching new operators one nozzle pressure sure makes things easy.

19. Originally Posted by fireslayer123
I agree with most of what you have said. However I can't buy into this part. Having a pistol grip helps to hang on to a hot hose line, or allows you to hang on for a longer period of time.
Tuck the hose up under your arm pit, grip down with your arm. Use your other hand and hold the nozzle just behind the coupling. Lean into it Try it, it might just work better

20. Originally Posted by fireslayer123
However I can't buy into this part. Having a pistol grip helps to hang on to a hot hose line, or allows you to hang on for a longer period of time.
As you've already been schooled on why the pistol grip promotes poor technique I'll direct my question in a different direction: Hot Hose? In 22 years I have yet to have the hose be to hot that I even noticed it. I have seen it get steaming hot when the operator forgot to circulate water through the tank for a long period with a line charged, but never in an actual fire. What is this in reference to?

21. ## Simple Physics

Interestingly the individuals who post in support of solid stream nozzles seem to understand the physics of nozzle reaction, but not the physics related to absorption of heat. Note that this is not an attempt to start a debate about fog vs. solid stream, both can be used to put out fires. However, surface area of the stream has a significant impact on the efficiency with which the stream absorbs water. The greater the surface area, the greater the efficiency. An effective stream is one that maximizes heat absorption at the location where the nozzle operator wants it to occur. Sometimes this involves the use of a straight (or solid) stream to cool surfaces and other times it involves fog to cool hot gases.

The decision to use low pressure nozzles should not be taken lightly. There are a number of fairly solid reasons to consider their use, but equal number in support of maintaining 100 psi nozzle pressure. These include increased cooling efficiency, stream density, and less kinking.

While I advocate 100 psi with combination nozzles, each agency needs to to an objective and scientifically based assessment on what they want to do and make their choice on that basis. Unfortunately the decision is often made on unsupported opinion.

22. Originally Posted by hartin
Interestingly the individuals who post in support of solid stream nozzles seem to understand the physics of nozzle reaction, but not the physics related to absorption of heat. Note that this is not an attempt to start a debate about fog vs. solid stream, both can be used to put out fires. However, surface area of the stream has a significant impact on the efficiency with which the stream absorbs water. The greater the surface area, the greater the efficiency. An effective stream is one that maximizes heat absorption at the location where the nozzle operator wants it to occur. Sometimes this involves the use of a straight (or solid) stream to cool surfaces and other times it involves fog to cool hot gases.

The decision to use low pressure nozzles should not be taken lightly. There are a number of fairly solid reasons to consider their use, but equal number in support of maintaining 100 psi nozzle pressure. These include increased cooling efficiency, stream density, and less kinking.

While I advocate 100 psi with combination nozzles, each agency needs to to an objective and scientifically based assessment on what they want to do and make their choice on that basis. Unfortunately the decision is often made on unsupported opinion.
Are you implying that we don't understand that with a fog tip the smaller particles are quicky evaporated an carried away from the main fuel source...by convection currents in the form of steam and do nothing to extinguish the main body of fire and steam the members of the nozzle team?

We aren't talking about fighting fires on Navy ships here.

When during a push down a hallway do we want to use this fog to cool the gasses? Why not just continue the push with the stream out and ahead breaking it up against the ceiling and upper wall surfaces while occasionally cooling the floor and working to extinguish the main body of fire that is producing those gasses.

Have you ever actually opened a fog stream while moving in on a fire in a building...I did when I was a young and inexpereinced FF with little leadership in the dept I was with at the time...it isn't pleasant and it does NOTHING to contain or control the fire.

I also hope you still don't believe in this "protection" afforded by fogs nonsense.

Your thinking is about 3 decades out of date....and misapplied to structure fires. There is plenty of science and written research along with plenty of experience to support our positon...I haven't seen much from the other side that makes much sense...or that works outside of a labratory setting.

FTM-PTB

23. Originally Posted by hartin
Note that this is not an attempt to start a debate about fog vs. solid stream
Too late now!

The decision to use low pressure nozzles should be taken seriously. More places should evaluate them and switch!

24. ## Science and Experience

FFRED,

I hear what you are saying and do not dispute that your approach can be effective at extinguishing the fire and I would use the same approach under some circumstances. However, when faced with a shielded fire that cannot be attacked directly, I would prefer to cool the gases overhead to reduce pyrolysis (in the immediate work area) and limit the possibility that the smoke (fuel) overhead will light up. This is a fire control, not extinguishment technique that supports, not replaces use of a straight stream. In this application, the droplets of water don't need to go that far. When reaching a location where the stream can be applied to the burning fuel, a straight stream provides the most effective way of extinguishing the fire.

There has been quite a bit of research that supports this approach outside that done by the US Navy that deals with fires in buildings. Much of this work has been done in Europe and not widely reported in our fire service publications. However, one example of research that supports this approach was conducted by the National Research Council of Canada (http://www.firetactics.com/NRC%203D.pdf). If there is research that supports your position I would be interested in having a look. Can you tell me where it has been published?

This is not just theory, While not commonly used here in the US, this approach is being used around the world (and even here in the US).

25. Originally Posted by hartin
The decision to use low pressure nozzles should not be taken lightly. There are a number of fairly solid reasons to consider their use, but equal number in support of maintaining 100 psi nozzle pressure. These include increased cooling efficiency, stream density, and less kinking.

While I advocate 100 psi with combination nozzles, each agency needs to to an objective and scientifically based assessment on what they want to do and make their choice on that basis. Unfortunately the decision is often made on unsupported opinion.
Chief can you explain how the same flow at a lower PSI has less cooling efficiency. Also, wouldn't the stream density be increased with less pressure but the same gpm? Due to reduced turbulence.

To me kinking is the only real concern when considering switching to low pressure. With reduced personnel keeping lines kink free is more difficult. But through proper training and technique this can be overcome. But, kinking is one reason that smoothbores are best suited for low pressure work (actually for almost all work, but that's another matter). Using a nice new TFT or Akronmatic low pressure nozzle, you'll have the same great looking stream without the gpm. With smoothbores you immediately know that you have a reduced flow due to the stream quality. So while it is rare, once in a while the best answer may be the easiest and cheapest.

While the solid stream off the ceiling may produce larger droplets than the fog, they are effective in cooling superheated fire gases. The bonus is that they are actually more forgiving of over use of the stream. Too much fog and the ceiling drops and we cook. Too much solid stream and things ahead of us get wet, with little steam. At the minimum: Right is Right and Left's for Lobster!

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