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Exposure Hose Lays
Hello all, we are discussing options to allow faster deployment of exposure lines without crippling an engine by taking up a pre-connected line solely with an Akron Ozzie that was bought by the Chief. Does anyone have any SOG's for exposure lines? Does anyone have the same situation and a good solution? Any feedback will be greatly appreciated. Thank you all!!!
Casey
Casey
Replies to This Discussion
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Permalink Reply by Paul Montpetit on
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That or they are running High pressure hoses.....Paul
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Permalink Reply by B.L.P.S. 13 on
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Wow! Seriously, this is simple math. Friction loss is 30 psi per 100 feet. Our nozzles regular nozzles require 100 psi at the tip to achieve their max gpm. The low pressure nozzles require 75 psi at the tip. This is simple "fireman proof" math, not rocket science.
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Permalink Reply by FETC on
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I hear brother, time is very critical. We have a few large buildings in my district in which have no standpipes for internal fire operations, therefore we have some 400-500 foot stretches to extinguish a fire. We have practiced using the aerial ladder which is equipped with a stand pipe elbow at the tip of the pre-piped water way with 1.5" threads. Works pretty well but it has to be there at the same time as the engine company is upstairs without water. This is sometimes a problem with us as the Ladder Company also crossmans our second out ambulance.
Therefore working on the critical time factor, the configuration in which "matches" your configuration would be how I have trained my company to (dry) stretch a 250' preconnect, 2-1/2" line into the building and upstairs until it is completely out, stop, break off the pipe and let another firefighter who carried the highrise pack, (150'-1 3/4" bundle with gated wye) add on to it. This is the same "one" connection make-up in which you have suggested with your dual 1-1/2" add on configuration.
The pressure would be lower in my scenario as with using the bigger line = less FL coefficient, greater gpm capability and we also added a smoothbore tip to the pack for less NP. Another plus I see is the next company can come right upstairs with just their bundle pack and connect onto the other side of the attack wye.
Not saying your way is wrong, not looking to argue, just saying there is many ways to move water.
FETC
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Permalink Reply by Jay Nicholson on
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Found this today.
The Newburg Volunteer Rescue Squad and Fire Department, Inc. was conducting a live fire training exercise on August 8, 2009 at Banks “O” Dee Road in Newburg, Charles County, Maryland when three volunteer firefighters were injured. The firefighters received injuries from a masterstream deluge gun that became dislodged from its staged location and struck them.
The department sponsored a training exercise with neighboring stations at a donated acquired structure. At the conclusion of the successful live fire training evolution, firefighters were wrapping up operations by dousing hot spots at training site. While water was flowing from the deluge gun, it began to slide out of position and whipped into the path of three nearby firefighters before it could be shut down.
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After I sent that I was worried that there might be some strange Aussie term for page. I'm not as good at translating Aussie as you are at English. ;)
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Permalink Reply by Jeff Cole on
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Without looking to get into a bitch fest, where did you get 30psi friction loss per 100' 1.5" hose?
A very common mistake is failing to consider manufacturer's specifications, which are different depending upon the brand of hose, and even the model, or series. The friction loss may = 'x' for a certain flow, but for higher flows the loss is higher as well. The ONLY way to accurately read your flows is with gauges and flow meters using your exact layouts and hose, and nozzles, as well as the various discharge gates on your apparatus.
With today's building materials and the much higher btu's, arriving quicker due to early automatic detection, and buildings being far more energy efficient, which means tighter...(obviously you are aware of this, this is no attempt to insult your intelligence), this should be every reason to increase flows. Now add into that equation the common problem of a lack of staffing, we need to look at shorter lays. At least WE do!
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Permalink Reply by Ben Waller on
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BLPS...I am paying attention, and that's why I'm calling shennanigans on some of your claims...
Our low pressure approach doesn't make us susceptible to kinks at all - we just run lines that flow more water per firefighter and use nozzles with 25 PSI less operating pressure than you do. We have had no problems with this system with extensive research and testing, with live fire training evolutions, or with real fires. It's possible to kink any line - even a 1-1/2 being pumped at 300 PSI.
We don't make up our own coefficient, we did real world testing with direct-reading instruments. We have onboard flow meters on our engines. Those flow meters are calibrated to within =/- 3% by the manufacturer, and certified as such. At 150 GPM, the flow meter won't be more than 4.5 GPM off from what's shown on the flow meter. If 150 GPM enter the line at the onboard flow meter, then you can be satisfied that pretty close to 150 GPM leaves the tip.
Further, even though they publish basic hydraulic calculations, IFSTA and several other fire service training groups tell you to conduct your own testing and to calculate your own coefficients rather than blindly accepting theirs. Those coefficients are THEORETICAL...in other words, they're theory, not real-world fact. The testing we did showed that we had a max flow 1.75 hose coefficient of 10 with a standard flow coefficient of 8.65...and we can prove it with direct-reading instruments.
If you haven't used flow meters to measure your actual flows with the layouts you're specifying, then it's probable that you don't know what your real coefficients are.
Check the IFSTA Friction Loss Coefficient Determination Chart on page 189 of the Pumping Apparatus Driver/Operator Handbook, 2nd Edition for the methodology for how to calculate your own real coefficients and actual flows.
Do you test your department's layouts with flow meters?
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Let's use the IFSTA "simple math" formula. Let's say that you have a 600-foot 1-1/2 line with your rule-of-thumb number, 30 PSI per 100 feet. that's 180 lbs of FL (30 x 6)in the hose. Add 75 or 100 PSI for the nozzles pressure you have, and that means that you're pumping as much as 280 PSI in the attack line. You can't take away the intake pressure, because the intake pressure isn't being pumped through the long attack line.
Here's the simple math...
C(Q squared) L where C is the coefficient, Q is the volume, and L is the length.
C = 24 for 1-1/2, according to IFSTA. So, if you're flowing 125 GPM, your formula looks like this...
24(1.25 squared) 6
24(1.56) 6
37.44 x 6
224 PSI just for the hose. If you're using a 100 PSI standard nozzle with 50 PSI of intake pressure, you add a net of 50 PSI, so you get 249 PSI for the 600 foot lay.
Now compare that to our leader line - we'd have 500 foot of 2-1/2 plus 100 feet of 1-3/4 and a 50 PSI tip. Put our system on your same water supply, and you get this:
C (Q squared) L for the 2-1/2 is
2( 1.5 squared) 5
2(2.25)5
4.5 x 5
22.5
The formula for the 1.75 is
C(Q squared)L
8.65(1.5 squared)1
8.65(2.25)
19.46
19.46 plus 22.5, is 41.96...close enough to 42. Add the 50 PSI for our nozzles, you get 92 PSI.
92 PSI instead of 280 the way we do it... with 25 more GPM per company.
I'll take that safety margin any time.
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Ok, take your safety margin and while you are standing outside trying to make your connections and recruiting some of the town folk to help you lug that contraption around, we'll just go in and put the fire out. I'm not guessing that will happen, I've see and been a part of it. If you don't like it, then simply don't use it. Not spitting out doctorine here.
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We do it with three-firefighter engine companies and we don't generally have out-of-town help since we're on an isolated barrier island in the Atlantic Ocean. We just go in and put it out, too. We just do it without stressing our hose, our engines, or our pumps unnecessarily.
We routinely have fires out of reach of the preconnects...setbacks, greenways, narrow, dead-end streets, condos with Side A pedestrian-only courtyards, buildings isolated by water on two or three sides, and any number of other access problems, so we know about long hose stretches.
You need to lose the blind spot and stop assuming that 2-1/2 equals "standing outside". It doesn't, just like using 1-1/2 doesn't make everyone that uses it too wimpy to handle real fire hose.
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