Smooth versus Fog ( Pros & Cons)

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Permalink Reply by Nate DeMarse on July 13, 2008 at 12:05am

Ah, the age old discussion. I'll join in for a few minutes.

I think that removing all fog nozzles from any department's engine companies is a decision that has been made without thinking about all potential scenarios that engines have to operate in. If a department decides to not use a particular nozzle for interior attacks, that doesn't mean that there is NO use for the other particular nozzle. Although I prefer a smooth-bore/solid stream nozzle over a combination nozzle for interior firefighting, I do believe that at least one or two combination nozzles should be available for the following circumstances: fires involving live electricity, dumpster/rubbish fires, car fires, foam operations, and decon and dispersing vapors at Haz-Mat incidents. Tommy Brennan used to say when he was asked many similar questions regarding the age-old nozzle debate. His line was something to the effect of, the type of nozzle used for fire knockdown is not going to make a good engine company perform badly or a bad engine company perform outstanding. There are other attributes that make or break engine company operations.

To answer your first question: What are the pros & cons for both combination and smooth bore nozzles:
Smoothbore Pros:
- Better reach & penetration ability than common combination nozzles (generally speaking)
- More water than a general combination nozzle when pumped CORRECTLY.
- Less nozzle reaction than a general combination when pumped CORRECTLY.
- Rust, small rocks and similar debris will pass through the nozzle (no screen) without restricting water flow
- Less thermal balance disruption if using hit & move tactics

Smoothbore Cons
- Lower operating pressures can lead to kinking if members are not careful
- Slightly more training so members are proficient in correct nozzle techniques
- Not as efficient as a combination nozzle when performing hydraulic ventilation
- More nozzle techniques need to be utilized to effectively operate the stream

I think that as with any tool or technique that we use, training is the biggest key of making it work the most effective. While the solid stream tip is not as efficient as the combination nozzle for hydraulic ventilation, I do not select my nozzle based on it's ventilation capabilities. I select my preferred nozzle on how much water it will flow and how easy it is to move in and operate. I heard this the first time yesterday for the guys that use "hydraulic ventilation" as a reason to utilize a combination nozzle. Ask them this, "How much water does your roof saw flow?" When they look at you funny, reply with "I don't pick my ventilation tool based on water flow, so why would I pick my fire attack tool based on it's ventilation capabilities"

I got a chuckle out of that so I figured that I would pass it on. In all seriousness, when the fire has been darkened down or extinguished and we are utilizing the nozzle for hydraulic ventilation, who cares about the efficiency of the smoke removal? We are in a slow-down mode at that point in the fire. Taking a few extra seconds with a smooth-bore line will move the same amount of smoke.

Combination Pros
- Has the ability to be used on all types of fires without switching nozzles as long as you are aware of the settings for each type of fire (structural - straight stream, cars - narrow fog pattern, etc...)
- Moves air more efficient for hydraulic ventilation (see note above)
- Less kink potential due to higher nozzle pressures

Combination Cons
- Higher nozzle pressure causes more nozzle reaction when pumped CORRECTLY, (generally speaking)
- Less water flow when compared to smooth-bore when pumped CORRECTLY (generally speaking). This translates to more work for less water.
- Increased work for the nozzle team (fatigue) due to higher pressures
- Screen will trap rust, small rocks or other debris and severely restrict flow or cease flow (very common with standpipes or draft situations)
- Members must check nozzle pattern several times during a fire to assure it is on straight stream (spun all the way to the right for straight stream, "right to fight".
- Some combination nozzles are very complicated with varied gallonage and other settings
- Some members still believe that opening up a nozzle in a narrow/wide fog inside a building is still an option for protection. In my opinion, anyone that has done this once, will never do it again. The chances of performing this technique and not immediately leaving the fire scene for the burn center is slim to none.

I have some concern with utilizing the technique that you described above to provide "self-cooling". I think that a straight stream (from any kind of nozzle) will cool the area down better if aimed directly at the fire area. I would be hesitant to aim a fog pattern away from the fire since it may cause the fire to be pulled over your head and over-run the nozzle team. I am not knocking what is being taught at anyone's fire academy, but that may be something to think about. Up until this post, I have never heard of that technique before.

That's all that I have,

Nate

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Permalink Reply by George H. Potter on July 13, 2008 at 5:39am

Nate, Todd and All,

Just a couple more comments to add to my last note:

- Everyone is on line about the possibilities of debris clogging the nozzle at the inside screen; you can verify and correct
this when you test flow before entering.

- If anyone has the opportunity to participate in Flashover training in a proper container (wood fueled) try diluting the
fire gases at the ceiling with the proper short spurts using a straight stream. Experience and practice (also textbook
study and creation) has show me at any rate that a 20 or so degree cone stream dilutes and cools these gases
effeciently and effectively. If you have doubts, try both and make your own conclusions.

- On the self cooling, the latest generation compliant turnout gear, or most of the preceding standads compliant gear
should not be wetted unless it is burning. When I started my FF career X years back, our canvas bunker coats more
often than not needed to be wetted down before entering a structural fire, and often when fighting heavily fueled
exterior fires as well. Nomex, Pbi, Kevlar, etc. were not even in their inventors' brains then.

All for now.

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Permalink Reply by Joey Lankford on July 13, 2008 at 9:40pm

Todd:

I am a proponent of smooth bore nozzles for attack lines. First let me day that both nozzles have their place on the trucks. Currently, I am trying to get my department to switch to smooth bore on "some" not all of the attack lines. I am starting to get the support of some of the members, who when educated on the proper use of each nozzle see the benefits of having the smooth bore in the tool box. One of the big selling points that I have found is less nozzle reaction, lower pressure, more gallons per minute.

I teach each summer at a large nation-wide fire school. My project is a three story burn building. During a normal summer we would "steam" anywhere from 30 to 50 students. This was not all our fault. Other projects would wet the gear of the students before their evoluation and then we would get a student with wet gear. I made the recommendation to the other instructors I work with and we tried it for a week. During that week we had NO steam related injuries. Since that time we have used the smooth bores and all involved like the change. This process took place about seven years ago and no one has complained. Instructors on the project are from all over the U.S. so there is a cross section of the fire service represented. We hear from the students that they were not aware of all the things that can be done with that style nozzle. We are the only project on the field to use smooth bores and the students are very interested in the different types avalable and how they are used.

Again, let me say that both types of nozzles have a place on the fire ground and education is the key to making the right choice.

Check out the tests conducted by the Oakland Fire Department and flows that they were able to achieve. Also there is much written by the late Andy Fredricks on the use of smooth bore nozzles. This information will provide you with a wealth of knowledge that my be of some help.

There are nozzles that all departments have in their tool box that in my opinion should be removed. The nozzle that I am referring to is the one that provides a firefighting stream no matter the pressure at the nozzle or the gpm's being delivered. This is a receipe for disaster.

Good luck and let me know if there is anything that I can do to assit you in any way.

Joey

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Permalink Reply by Marty Hamrick on July 15, 2008 at 9:27am

Brother, we reciently upgraded to an Akron break apart. It's a constant gallonage fog tip (175GPM @ 75PSI) that can be removed that leaves a 15/16 smooth bore shutoff. To me it's the best of both worlds. By far, i perfer the smooth bore. But, like other brothers have said, there is a place for all the tools. The key is knowing how and when to use them. Buy the way, the fog tip...I can drop pennys, nickles, and dimes through it, the clogging comes into play with the automatic fog... which I believe is the antichrist! Avoid it at all cost.
Hope this helps.

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Permalink Reply by Chris Fleming on July 18, 2008 at 9:32am

George,
225GPM on an 1 3/4" Line sounds a little high, and 380+ GPM sounds outrageous. The physics behind that doesn't seem to work. Were these flows checked with an in-line flow meter that was properly calibrated? Salespeople will tell you what you want to hear and some may even go so far as to "fudge" things to make a sale. If they use their flow meter, I would be suspect. Then again I'm kind of a cynical guy. Also, the nozzle pressures of 70-90 psi seem off. The low pressure fog nozzles I've seen on the market are either 50psi or 75 psi; other than that the nozzle pressure is 100psi. Some of the other points you make in the characteristics of combination streams make me wonder as well. Wide angle "water curtain" for self protection does nothing to stop radiant heat and would contribute to steam production, which if one is in the same compartment as the fire, is all bad. The variable flow and stream angle are also problems. BTUs are beaten by GPM, not psi. If your GPMs are too low you aren't going to be able to extinguish the fire. It may run out of fuel and the BTUs may decrease to a point where less GPMs will extinguish the fire, but this increases firefighter exposure time. The wider the stream angle the closer one has to be to the fire to apply water. This also increases the danger to the nozzle team. That being said, I agree that one nozzle will not do it all, and fog nozzles are better for vapor dispersal and foam application.
As for the "Mystery Nozzle", it was explained to me that it's the variable gallonage automatic nozzle and the mystery was what you gpms were and whether the fire would go out.
Chris

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Permalink Reply by George H. Potter on July 18, 2008 at 3:35pm

Chris,

If my memory doesn't fail me, the 225 gpm is the flow rating for a relatively new nozzle by Akron, publicized as being adquate for hi-rise intervention. I have a Spanish made (TIPSA) which does flow approx. 225 gpm at around 60 psi.

The 380 gpm nozzle was a prototype built by TIPSA in the mid 90's that resembled a bazooka ( more than 20 inches long and average of 5 inches or so outside diameter) and weighed some 15 pounds! We did not have a flow meter to verify the exact output, we emptied the 775 gal. tank of a Spanish built pumper in just under two minutes (at 2 minutes the pump cavitated for lack of water). OK, not very scientific but the two FF's handling the nozzle at the end of 100 feet of 1 3/4 id. hose as well as the rest of the group of Spanish FF's were all pretty impressed. The bazooka was the only example of this design ever built and now holds an honored place in a Spanish fire protection engineer's collection.

You are quite correct about the 100 psi as the norm for fog nozzles. Again, Akron and I believe Elkhart and possibly TFT have low pressure fog nozzles in the market. These have been developed with hi-rise use in mind.

Maybe the break apart concept would provide the versitile combination. I stand firm though on my statements about narrow fog being the RIGHT stream for reducing the potential risks of Flashover.

In Europe, a great deal of practical, live fire research / investigation has been undertaken in interior fire combat. One of the essentials for obtaining a viable and reasonably safe environment inside a burning building is reducing the risk of Flashover; dilute and cool the fire gases accumulating at the ceiling before they can ignite. Most European cities and towns, not forgetting rural areas, are not blessed with USA type dedicated fire mains. More often than not, the European FF's must depend on the water carried on board their engines to attack, contain, control and extinguis their fires.

Be safe over there,

George

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Permalink Reply by Marty Hamrick on July 18, 2008 at 3:50pm

Also, like Andy Fredericks, I agree that straight or soild streams are the thing to use on aggressive interior attack.

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Permalink Reply by Chris Poyner on August 4, 2008 at 4:33pm

Hey real quick.We have both on our engine(smooth and combination)For interior fires i prefer the smooth bore.

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Permalink Reply by Greg Wyant on August 6, 2008 at 11:26am

I am glad to hear another Department has come around in todays world the solid stream is the only stream for interior fire attack. But it is like any other tool you have to train train train. Look up anything you can find that Andrew Fredericks wrote he puts in in plane english.

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Permalink Reply by Dave Dodson on August 8, 2008 at 12:27pm

Hi Todd:

Always a fun and spirited topic to debate. As I travel about, the debate is brought up in virtually every department! And while I feel our firefighter safety debate energy should be channeled to higher priority topics, this one is pretty fun.

As for my feelings - I'm a tool box kinda guy. Have options and use intellectual understanding of the situation to pick the right choice. Sounds like a cop-out? Perhaps. Without getting too technical, I'll get specific: The training officer in me likes smooth bores. Easier to teach, harder to get into trouble. The nozzle person in me likes the versatility of a combination nozzle - especially the low-pressure models that are starting to flow in (bad pun intended). Trust me though, if the combo nozzle has a poor straight stream, give me the smooth bore. High rise packs - smooth bore (weight and punch). Ideally - and this may be our future: 1 3/4" preconnects are loaded for three choices: smooth bore for interior and transitional attacks, combo for foam (and hazmat, odors, etc.), and a piercing nozzle for lightweight wood buildings (basement/truss loft fires) and vehicle fires.

thoughts?
-Dave

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Permalink Reply by David Rhodes on August 8, 2008 at 2:19pm

You need both types of nozzles and then select the right one for the right job. The solid bore nozzle gives you better reach and, higher GPM and requires a lower operating pressure. It also does a good job knocking out drywall ceilings and walls. The combo nozzle is good for exterior exposure protection, LP tanks, and hydraulic venting (both Positive and Negative Pressure). I would suggest (depending on your Engine set up) that you run with 1- Combo nozzle equipped pre-connect and 1 - Solid bore pre-connect. This would give you the flexibility of having both. You could do the same on your skid load. Make the solid bore your first in line. If your department requires all nozzles to be the same then determine what you need your nozzle for the most (putting out a structure fire - solid bore, hydraulic venting - combo, LP tank cooling - combo etc.) Whatever you do insist on a solid bore or breakaway solid/fog nozzle for your high-rise pack!

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Permalink Reply by Greg Wyant on August 9, 2008 at 9:03am

One department I have been with started out with the combo breakapart so the men could get use to the idea of the smooth bore without feeling that it was being shoved down their throats. After 6 months of training they take the fog tip off at all structure fires . Now Iknow of two other departmrnts starting off with the breakapart.

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