75psi vs 50 psi fog nozzles?

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Permalink Reply by Larry Lasich on March 18, 2009 at 1:25pm

http://00691ee.netsolhost.com/index.htm

They just cost a fortune.

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Permalink Reply by Bob Franklin on March 20, 2009 at 12:27am

Hey Nate,
Several years ago I did a two year study in attack nozzles for our fire department.. We requested nozzles from every manufacture for a 6 moth trial period. We found that the Elkhart 4000-16 with a 150tip @ 50 psi nozzle pressure. The nozzle was flowing 146/154 gallons per minute. We can have a pump discharge pressure of 90 to 100 and produce a very effective fire stream with very little nozzle reaction. We are using 1-3/4 hose in 200 Ft. crosslay. We also use a 15/16 smoothbore on our aother crosslay which has worked out very well.

Hope it helps brother! Come see me at FDIC at LET'S TALK PUMPS
BOB

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Permalink Reply by Ricky Teter on March 20, 2009 at 8:31am

Do you guys have problems with hoselines kinking easily when pulling corners or advancing on stairs?

Bob Franklin said:

Hey Nate,
Several years ago I did a two year study in attack nozzles for our fire department.. We requested nozzles from every manufacture for a 6 moth trial period. We found that the Elkhart 4000-16 with a 150tip @ 50 psi nozzle pressure. The nozzle was flowing 146/154 gallons per minute. We can have a pump discharge pressure of 90 to 100 and produce a very effective fire stream with very little nozzle reaction. We are using 1-3/4 hose in 200 Ft. crosslay. We also use a 15/16 smoothbore on our aother crosslay which has worked out very well.

Hope it helps brother! Come see me at FDIC at LET'S TALK PUMPS
BOB

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Permalink Reply by Kevin Nowicki on March 20, 2009 at 8:48am

Nate,

It is very simple for me. Less pump discharge pressure, equals more line potential, equals greater fire flow potential, equals more efficient service. I could even make an argument it reduces wear and tear on the apparatus which is important to me since I look at the apparatus as a life support system for me and my guys. Save the truck, save a life!

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Permalink Reply by Antiquefirelt on March 21, 2009 at 1:41pm

How about justification for the 1.75" fog nozzle? 50 psi SB equals cheap, simple, and least likely to fail.

The one point that makes sense to me, if looking at fog nozzles would be the "kink factor". The 75 psi will be more resistant to kinks but still less reaction force. Right is right, left for Lobster.

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Permalink Reply by Nate Brown on March 21, 2009 at 4:33pm

Thanks for the great feedback! I agree with the advantages of low nozzle reaction and less pump stress, but I don't believe it is worth taking a limp hose into a structure fire. I always tell my pump operators to add 10 to 15psi to avoid this because we currently have 50psi fog nozzles. Unfortunately we switched from 75psi fog nozzles several years ago so I have used them both and the advantages of a little less nozzle reaction and pump stress don't justify me and my crew going into a structure fire with a limp hose!

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Permalink Reply by Gerald Dedo on September 17, 2011 at 8:52am

Not to start SB or fog nozzle debate, but, should not a line feel and act the same way with X amount amount of water and X amount of pressure regardless of the nozzle type. 150 gpm at 50 psi should be the same in the hose no matter what is on the end.

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Permalink Reply by Larry Lasich on September 17, 2011 at 11:59am

If you are asking about nozzle reaction, there is greater reaction from a 75 or 100 psi fog than from a SB running the same gpm.  Lower pressure is always better.

 

Nozzle reaction for solid streams

NR=1.57*d sq(nozzle diameter) * NP

 

Nozzle reaction for Fog Streams

NR=0.0505*total flow in G.P.M.* sq root of NP

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Permalink Reply by Michael Bricault (ret) on September 17, 2011 at 12:08pm

-OK, I know this isn't the answer to the initial question but it needs to be said based on where this conversation is going and in response to Ricky Teter's comment.  If your lines are kinking during the advance it is an indication of poor hose handling and not the fact that there isn't enough pressure to prevent kinks. 

-For years before the 1 3/4 hose, 1 1/2 lines with a smooth bore nozzle were standard; ie. low pressure, and the fire attack went just fine because firefighters were trained in proper hose handling.  Exaggerated movements in advancing and corner following, placing back up men in proper locations down the line, proper stretching techniques and chasing kinks early.

-Kinked lines, too much/too little hose and spaghetti messes on the street are examples of poor hose handling.  Depending on the driver to ramp up the pressure to, "blow out the kinks" is poor hose handling.

-Proper hose handling in the American fire service is fast becoming a dying art.  It's much easier for firefighters to have a  knee-jerk reaction to firefighting and pull the 200 ft. pre-connected 1 3/4 at every fire first and hope that it will reach and be sufficient because it worked just fine last time.  Makes me wonder how many fires are being suppressed by firefighters verses actually just running out of fuel.

-While teaching at a conference I asked the attendees what would be some deciding factors as to pulling the pre-connected knee-jerk verses the 2 1/2 off the static bed; something that requires estimating distance, proper stretching techniques and the necessity to proper advancing to avoid kinks.  I expected the ADULTS acronym, what I got was a mixture of answers ranging from neophyte, amateur and just damn foolish.

-An old timer once told me, back in the days before everything was an acronym, "If the fire has control of two residential sized rooms, if the fire is of an undetermined size/location, if the fire is in a commercial occupancy, if the stretch is going to take you up/down stairs... pull the 2 1/2 !!!  Tom Brennen was right when he said that the 2 1/2 is our most potent hose line weapon and there's not much that will defeat it if properly used. 

-Firefighters today are entirely to reliant on the 200 ft. pre-connected 1 3/4 line with a fog nozzle; to many lucky outcomes reenforcing bad decisions.  Yeah, yeah I've heard the, "but I seen it put out a lot o' fire" B.S. a thousand times.  Bottom line is it's sloppy and unprofessional to rely on this damn line as much as the fire service does.  And now we have a situation in which an entire generation of firefighters/officers are so afraid of the 2 1/2 pulled off the static bed that they will make up all kinds of excuses to not touch it so as to mask their own ineptitude. 

-Now, to end my soap box rant; proper hose handling is becoming a dying art form and if we're not very careful here it will soon go the way of proper ventilation evolutions and the Dodo bird; all but forgotten to the sands of time. 

Ricky Teter said:

Do you guys have problems with hoselines kinking easily when pulling corners or advancing on stairs?

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Permalink Reply by Michael Bricault (ret) on September 17, 2011 at 12:11pm

-Limp??? Do you prefer the hose feel like an immoveable, unbendable, unmanageable steel girder?

Nate Brown said:

Thanks for the great feedback! I agree with the advantages of low nozzle reaction and less pump stress, but I don't believe it is worth taking a limp hose into a structure fire. I always tell my pump operators to add 10 to 15psi to avoid this because we currently have 50psi fog nozzles. Unfortunately we switched from 75psi fog nozzles several years ago so I have used them both and the advantages of a little less nozzle reaction and pump stress don't justify me and my crew going into a structure fire with a limp hose!

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Permalink Reply by Nate Brown on September 17, 2011 at 3:03pm

 

Michael

 

I think you are missing the point of the original discussion. Open your mind for a minute to recognize that my question starting this thread was only concerning the comparison of 50psi fog nozzles with 75psi fog nozzles and nothing else! The nozzle reaction from a 75psi fog nozzle is comfortable to me, so my next concern is the hose presentation during use. I know they used lower pressure smooth bore nozzles in the old days, but they also used 1 ½ hose which created more friction loss. This meant higher pressures even though you had a 50psi nozzle. This allowed the hose to stay stiff. And yes! I do want some stiffness in the hose. The goal is to have the right amount of stiffness! Not impotence, but not Viagra stiff!

 

My preference is to use an 1 ½ 75psi fog nozzle because you can get 150gpm, some stiffness in the hose and very manageable nozzle reaction. It seems to me that this is a happy medium that can reap the benefits of both a 50psi and 100psi nozzle.

 

Your “Soap Box” on proper hose deployment is something I agree with. I stress to my crews to lay out their hose lines properly before any entry. If they don't, "It gets fixed before we go in!" The problem I don't think you recognize is that crews have gotten smaller and smaller over the years because of minimum staffing. Our Department is able to meet NFPA's minimum staffing on a structure fire, but there are many times when it is just two firefighters deploying a 200ft hand line into multiple stories.

 

I personally believe that there is a lot to learn from “Old Timers”and it p***** me off when I see guys retiring without passing on their knowledge! But, please consider that equipment is more advanced and manpower is down from when they were in the Fire Service!

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Permalink Reply by David Polikoff on September 17, 2011 at 6:45pm

We use low pressure nozzles fog with a break away and a 7/8 slug attached. The fog and the slug are pumped at 50 psi therefore the pump operator need not adjust his pump when the nozzle man switches.

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