Nozzle Series - Smoothbores

[@dankerkstra6305]

Thanks for the video. Well presented and good info to either review or if learning for the first time.

[@Boxalarmtraining]

Dan Kerkstra Thank you very much. We have several more on the way.

[@megaweld7018]

Good Stuff !!!👍

[@semproniodensso3353]

A lot of FF are convinced with old suppositions. But the reach and penetration from a correctly trimmed straight stream from a fog nozzle has more of both, reach and penetration. Starting for pressures and velocity, 100 psi in fog nozzles against 50 or 80 psi in smoothbores at the same GPMs. But fog nozzles are more versatiles, you don´t need to close the water for changing tips, then looking for a place where store the tip, or looking for the tip for reinstalling because a lesser new flow. In selectable foggers you only rotate the ring, in auto nozzles with slide valve, the SAME on/off valve serves as GPM control.

[@Boxalarmtraining]

I understand the notion that fog nozzles are more versatile, that is a very notable observation. But, in reality, a lot of what you just mentioned has been proven in numerous research studies to be misguided as "old supposition" itself. The reality is GPM is the single biggest determining factor when absorbing heat energy from a fire, and thus extinguishing it. Fog nozzles are available in lower pressures such as 50 and 75psi, however they are much heavier and when reduced to lower operating pressures a host of other issues occur such as nozzle whip. So, the vast majority of fog nozzles in operations are being operated at 100psi which causes a ton of issues. The selectable gallonage nozzle only works if the pump operator is communicated with to adjust the pressure feeding the nozzle. Same with the automatic. The bale itself will only "regulate" the amount of water given to it. The pump itself is what is delivering that flow to the nozzle. Without a substantial amount of communication these nozzles simply do not work as intended during real situations and real stress. This is most noted in the One Meridian Plaza fire which took the lives of three firefighters. A huge contributing factor of that fire was the use of automatic fog nozzles. Paul Grimwood of the London Fire Brigade discovered that the "average" firefighter can withstand and operate approximately 60 pounds of nozzle reaction... This is where things become significant. I personally conducted a nationally published research paper for the National Executive Fire Officer Program which showed that firefighters without very specific training lack the ability to "feel" their actual flow. In fact, over 50% of the test subjects did not detect a 25% reduction in flow from their nozzle when using the 100psi fog nozzle. This is because the higher pressure conceals issues that are difficult to detect. On the actual fireground we have seen demonstrated losses in pressure of around 10-15% as noted in Vestal and Bridge's research, "A Quantitative Approach to Selecting Nozzle Flow Rate and Stream - Part 1". This is a considerable drop in fireground flow that is typically completely ignored when "learning" about these topics in text books. Real world examples are abundant and have been demonstrated in numerous research projects. A lot of what you mentioned is accurate, however, a lot is also opinion and not backed with scientific research or data. We have an abundance of data which suggests the smoothbore is significantly better for interior structural fire attack. It is NOT better for the other varieties of fires, which you correctly mentioned the fog nozzle versatility. That being said, I appreciate the comment and discussion. Many of our firefighters need to understand these topics and very little information is shared in the text books regarding the significance of real world test results. Most of the classes taught, are taught in theory.

[@semproniodensso3353]

@@Boxalarmtraining Thanks for your response...I teach hands on using 1-1/2" 50-250 gpm Sho Flow flowmeters, I have two of that old spring loaded model. Both pitoted and give a very precise reading. The reaction force it´s very useful for "feeling" the actual discharged GPMs. When using smoothbore nozzles you have EXACTLY the very same problem about gpms as with traditional fog nozzles, being auto or manual, without comunication with the pump operator he hasn´t way for knowing how much or less pressure must pump, but with autos he/she only have to pump for a preselected pressure as 150 or 200 psi for a preconnect and the nozzle operator selects the flow he/she needs, all of this without the need of comunications...as you know, the first things to burn in a fire are the communications. Higher pressures conceal flow issues only in non automatic nozzles, a low flow opening selected, but with high pressure, if the FF didn´t see the selected gpm will fedback as it is flowing high GPMs, the same with smoothbores, but auto nozzles will have reaction force proportinal in straight line with the flow being discharged, in SBs or conventional (fixed/selectable GPM) fog nozzles, the reaction grows up EXPONENTIALLY with increase in pressure. Teaching the feeling of GPMs in auto nozzles itsn´t rocket science, it´s easy to learn and understand. Grimwood coming from UK fire service, considers 200 gpm a very high flow from a nozzle, but 250-300 gpm in straight stream can be controlled WITHOUT over exertion just seating over the hose, and higher flows, such as 400-500 gpm from 1-1/4" at 400 gpm at 80-90 psi, two FF seated behind the nozzle control it easily. For interior attack you didn´t need high flows, ususlly a 100 or less gpm will suffice. For exterior attack, you need stream capable of penetrating the flames, and still, after of travelling 20 or 40 ft, have enough "surviving" flow for absorbing the heath wich maintains the pyrolisis...not the flames heath.

[@BenSingley]

@@Boxalarmtraining Love this conversation. I do wonder about the concepts you mentioned about identifying reduced nozzle reaction. I'm fully on board with your findings that it is harder to identify reduced flow when the nozzle reaction already starts high, but did your study compare low-pressure combo nozzles (specifically automatics) to the other nozzles? The nozzle reaction for our 50 psi Chief XD fixed gallonage nozzles is the same as our 7/8" smoothbores when flowing 150 gpm at 50 psi, so I'd assume your findings for the 7/8" nozzle in your study can be reasonably assumed to be applicable to a low pressure straight stream of equal NP & GPM. I'd also think it would be fair to make the same assumption about a low pressure automatic nozzle, but this is where I wonder if you have better information. You mention it in the Automatic nozzle video, but the only real way to ensure adequate flow is through a flowmeter or through nozzle reaction. I feel like the statement "you don't know how many GPM you are getting out of an automatic nozzle" is just as applicable to a smoothbore or fixed gallonage low pressure nozzle as it would be to a low pressure automatic nozzle. Ultimately, if you are interior in low/zero-visibility conditions, you won't be able to see a reduction in stream quality for your smoothbore or fixed gallonage combo, and shouldn't be relying on that to determine adequate flow anyway. All three nozzles will have a reduction in nozzle reaction with reduced flow conditions, and to the same degree, so at that point, are you still against the automatic nozzle, or does the use of a low pressure automatic nozzle assuage the concern of "concealed" flow issues? I'm doing a deep dive into both parts of "A Quantitative Approach", and have read some of your work as well, and am still coming up with a fair share of questions. Looking forward to the rest of your video series, as I work through it almost 10 years later! Cheers!