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  1. #21
    Forum Member len1582's Avatar
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    We started using 1 3/4 in the early-mid '80s and it's a good line.Just because you can flow 200gpm means you have to use it all the time, just use some control over the little bitty handle and you can wet down a mattress. But when the door gets pushed open and you're face to face with a few rooms of hell and you need more than 125gpm to go after it and protect yourself at the same time,it's good to have that extra.As far as weight it's not all that bad,you don't notice it if you don't think about it.We also have 3,4, and 5 story walks no stand pipe.
    I know one dept many years ago tried 1 3/4 and used the old 1 1/2 nozzles and wondered why they didn't get more water.You need both.


  2. #22
    Forum Member EastKyFF's Avatar
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    Some more math:

    Volume of water in a 50' section of 1.5: 2.45 cu ft
    Volume of water in a 50' section of 1.75: 3.44 cu ft
    Difference: Roughly one cubic foot
    Weight of one cubic foot of water: 8 lb

    So given a 200' preconnect, using 1.75 adds 32 pounds of water, or 75% of what my five-year-old daughter weighs. Darley's web site lists 1.5 at 17.5 lbs/50' and 1.75 at 18.5 lbs/50'. That means four pounds of extra hose weight per 200'.

    Grand total: 32 pounds of water, four pounds of hose: 36 pounds heavier per 200'.





    Now that I'm through playing Bill Nye, Science Guy, here's an empirical statement: We switched to 1.75 a few years back and I never noticed a difference.

    Sorry for the CPA-like digression, but we got our taxes done yesterday.
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  3. #23
    Forum Member Rescue101's Avatar
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    But did you notice a difference in knockdown capability?T.C.

  4. #24
    MembersZone Subscriber SamsonFCDES's Avatar
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    Originally posted by arhaney
    We recently changed to 1.75 attack hose. I love the increased knock down of the increased GPM's you can deliver! On the down side you do have a lot more reaction force to deal with at the higher nozzle settings. My advice.......if you can't handle it, just turn down the nozzle. The other down side for a rural department is your water supply, you can empty that 1,000 gallon booster tank in 5 or 6 minutes easy! But at the same time darken the fire so much quicker.
    I am glad you bring up the water supply issue. I come from a rural VFD that has no fire hydrants in its 730 square miles. What we do have is 2 4500 gallon tenders, and the biggest booster tanks GVW will allow, on our Class pumper that is 1000.

    You can go through that much water, 10000 gallons, in 10 minutes if we are pumping full on with the deck gun and attack lines.

    You better get it out with that, the nearest backup water is at least 20-30 minutes away.

    We are likely never going to change from 1.5 attack lines, not only because of the water supply, but because it is way to expensive! We have an adequate supply of 1.5 inch hose we add to when possible/needed. To change over completely to 1.75 inch would wipe out the entire years budget...

    1.5 is just fine by us, it has to be, that is all we get!

    On a similar note, it was mentioned that anything smaller then 1.5 is useless. Well, we have found out otherwise, and not by intent.

    Our 20 old Class A pumper has a steel tank which is flakeing off its lineing. The inch diameter blue pieces of whatever are now makeing their way down attack lines and plugging up the nozzles at the inlet screen! This realy sucks, as was demonstraited at a farm yard garage fire recenlty. We pulled up to find a garage 20x50, a converted old chicken coup actualy, half fulling involved, with the second half (divider wall) just starting to get going. Lots of paint cans poping. I had one 1.5 inch line at the garage door, getting ready to open the door, and there was another 1.5 protecting an exposure. Pumper starts pumping, Cap opens the door, 30 seconds of decent flow... then it started flowing realy weak, cranked the patern aduster over to flush, no help. Both 1.5s had plugged! At that time 2 of our brush trucks had shown up and parked within the 150 foot range of their 1" hardline reels. We dropped our 1.5s, yelled at a rookie to fix the @$#% nozzles, grabed the 1" booster lines, and went back to the attack with the little brush truck pumps screaming full blast. I would imagine that with the nozzles we had, variable gpm, that we were putting out roughly 60 gpm on each line, comeing off of 400 gallon tanks on the brush trucks. We did get the fire out before the 800 gallons we had on tap was used up, but we had to get more water to catch the small (<3 acres) grassfire that had started up in the pasture next to the garage.

    1" lines do work, but they do not inspire a world of confidense. It is way to touch and go. IIRC in the UK they use a LOT of 1" hardline to attack their structure fires. But, they have a LOT of masonry buildings, not so many stick built. They can limit water damage by useing the smaller lines, and their fires are often confined to single rooms for apartments.

    I dont know what the max flow out of a 1" hardline can be, but I am guessing 75 gpm or so.
    -Brotherhood: I don't know half of you half as well as I should like; and I like less than half of you half as well as you deserve.
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  5. #25
    Senior Member Dalmatian90's Avatar
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    Of course, go with CAFS and the weight issues go away and you get improved knock down to boot

    Thinking about this some more, the times I notice the weight difference is when we're short-handed, 2 guys on a line, or just myself outside moving one around. Interior attacks with three sets of hands on the hose, two near the nozzle and one helping around corners it's not an issue. 2 guys both near the nozzle, that's 32 more pounds, and probably more friction (larger outside surface), that the backup man is pulling...you notice it.

    People talk about bigger fire loads with today's plastics and such, but that's only part of the story. Most fires we fight inside are oxygen-limited -- it's the amount of fresh air getting to the fire that limit their size & BTUs per minute the fire is generating. When you see a room that you can "look" through, that's complete combustion. Usually only see that on training fires with every window knocked out, or on the odd fully-involved and well vented building. Seen it a few times on a real fire with really good ventilation.

    Usually with windows in place, doors closed, etc we still aren't putting more oxygen in there than we did in the 1950s. Maybe the plastics light off a little faster, but burning wood & cloth ignites pretty easily too. Maybe some of us push a bit more oxygen at it through PPV. Given the same size rooms, we're probably not seeing more fire than grandpa.

    We do have some other stuff -- bigger rooms, more open floor plans that can affect us (especially with these damned McMansions with flyweight* frame construction). Bigger room, better airflow, energy efficient to keep the heat/smoke in longer preventing detection could add up to bigger fires.

    But in a district like mine, the ranch houses built in the 60s and 70s, the capes built in the 20s and 50s, and the colonials built, well, back in colonial days, all probably put out about the same BTUs per minute for room & contents or 2-3 rooms lit off as they did 40 or 50 years ago -- air supply limited wood & cloth furnishing fires, air supply limits plastic-based furnishing fires.

    Yep, the potential for more BTUs is there, but the reality is they fires probably aren't burning that much hotter. Yep, PPV could do that, but that's why we coordinate fire attack. Yep, plastics are gonna be more likely to produce copious amounts of "black" smoke that's more likely to roll & flash as fresh air reaches it, but again, that's something we need ventilation for -- better to eliminate the potential then hope we have enough GPM to overcome it. If the smoke isn't over your head, it's ain't gonna roll over you. If it rolls over you, you might have enough GPM in your hose -- 1.5", 1.75", even 2.5" to overwhelm it. Yeah, 2.5" more likely to handle it, but not as assuredly as ventilation can make it safe. I don't mind facing a lot of fire, I don't like a lot of hot, black smoke near me.

    1.5" volumes, 95-125gpm were adequate 40 years ago, and with oxygen being the limiting factor on most fires, is still just as adequate in the same buildings. Flow has to be accompanied by nozzlemanship, and I think a lot of times we've tried to keep increasing the amount of GPMs thrown at a fire as we, as a fire service, have let nozzle skills slip. Too often we throw water everywhere, some of it may actually hit the fire. Nozzlemanship can put the appropriate flow on the fire, and when you use good nozzlemanship the flows needed are often dramatically less than what is commonly instructed today.

    If anyone has emperical research why we keep bumping up the flow rate recommendations, I'd love to see it. I have a feeling most of it's just been "consensus" of well, if 1.5" was good, 1.75" gonna be better. And if 150gpm through a 1.75" was good, 200gpm must be even better. As you keep bumping up to handle the high end, the skills at the low end keep slipping.

    I don't mind the 1.75" and 2" lines, it's just the 1.5" seems to be under-appreciated and I think most of the time it's been criticized can be tracked to either poor nozzlemanship (they didn't put the wet stuff on the red stuff, just shot it in the general vicinity), or poor size-up to pull an under-powered line to begin with. As a utility line for outside fires, and a quick & manueverable line for a short-handed crew on modest interior fires it's a valuable tool.

    *Flyweight: I'm wondering if a new term is needed to go beyond the "lightweight" wood construction of the 70s/80s that at least used solid wood if in small dimensions to this new particle-board I-beam world of today!
    Last edited by Dalmatian90; 04-06-2004 at 01:25 PM.
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  6. #26
    Forum Member EastKyFF's Avatar
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    You know, so much of this water flow stuff distracts us from the real goal, which is not so much delivering gobs of water but placing water where it's needed. The only reason we need 150 (or 200, or however many) GPM is that we don't always have the visibility or access to make a "love connection" with the seat of the fire.

    I'd bet that a pretty large percentage of the water we deliver is really just insulation--that is, with straight streams we are using the water on the outside of the stream to absorb BTU's and allow the inner part of the stream to remain in liquid form until it reaches the fire we are actually aiming for. If we could inject water directly to the seat of the fire and let steam expansion follow the heat currents through the rest of the fire, it would probably be astounding how little water we actually used. Because this is not fully possible, we still have to overkill it on water. Add to that the blind spraying we do in bad visibility and we're looking at major water usage.

    And to answer the question regarding my earlier statement about weight of 1.75 vs. 1.5, I'm not sure about knockdown as we have upgrade the hose first and not the nozzles yet. Gotta start somewhere, and they don't give this crap away, do they?
    "Be polite, be professional, but have a plan to kill everybody you meet.”
    --General James Mattis, USMC


  7. #27
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    Originally posted by EastKyFF
    Some more math:

    Volume of water in a 50' section of 1.5: 2.45 cu ft
    Volume of water in a 50' section of 1.75: 3.44 cu ft
    Difference: Roughly one cubic foot
    Weight of one cubic foot of water: 8 lb
    Actually, one cubic foot of water weights about 62.4 pounds. One gallon of water weighs 8.34 pounds.

  8. #28
    Forum Member FireCapt1951retired's Avatar
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    Originally posted by Dalmatian90
    Flow has to be accompanied by nozzlemanship, and I think a lot of times we've tried to keep increasing the amount of GPMs thrown at a fire as we, as a fire service, have let nozzle skills slip. Too often we throw water everywhere, some of it may actually hit the fire. Nozzlemanship can put the appropriate flow on the fire, and when you use good nozzlemanship the flows needed are often dramatically less than what is commonly instructed today.
    BINGO Dal,
    One of the best statements in this entire thread.
    Give me my Rockwood back and let me GO TO IT
    Last edited by FireLt1951; 04-06-2004 at 05:36 PM.

  9. #29
    Forum Member Rescue101's Avatar
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    Yep,put out a lot of fires with a Rockwood.Learned a lot too,like when the dragon breathes back those feet had better be bi-directional.I think I'll stick to my 1.75 and SM20,the feet are getting older and the bi-directional's not as quick as it used to be.The beatings aren't as enjoyable either.T.C.

  10. #30
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    Originally posted by EastKyFF
    Some more math:
    Volume of water in a 50' section of 1.5: 2.45 cu ft
    Volume of water in a 50' section of 1.75: 3.44 cu ft
    Difference: Roughly one cubic foot
    Weight of one cubic foot of water: 8 lb

    So given a 200' preconnect, using 1.75 adds 32 pounds of water, or 75% of what my five-year-old daughter weighs. Darley's web site lists 1.5 at 17.5 lbs/50' and 1.75 at 18.5 lbs/50'. That means four pounds of extra hose weight per 200'.

    Grand total: 32 pounds of water, four pounds of hose: 36 pounds heavier per 200'.
    Let's try it this way:

    The Volume of hose is:
    V = A x L (Area times Length)
    Area = (Pi x D^2 / 4) (You forgot to divide by 4)
    The Area must be expressed in square feet.

    Therefore, for 1-1/2" Hose:
    A = Pi x [(1.5/12)^2] / 4
    A = 0.01227 Cubic Feet
    V = 0.01227 x 50Ft
    V = 0.6136 Cubic Feet
    Density of Water = 62.4 lbs/cubic foot (as erics99 stated)
    Weight of Water = 0.6136 x 62.4
    Weight of Water = 38.3 lbs in 50 feet of 1-1/2" hose
    Weight of Water = 38.3 x 4 = 153.2 lbs in 200 feet of 1-1/2" hose

    For 1-3/4" Hose:
    A = Pi x [(1.75/12)^2] / 4
    A = 0.01670 Cubic Feet
    V = 0.01670 x 50Ft
    V = 0.8352 Cubic Feet
    Density of Water = 62.4 lbs/cubic foot
    Weight of Water = 0.8352 x 62.4
    Weight of Water = 52.1 lbs in 50 feet of 1-3/4" hose
    Weight of Water = 52.1 x 4 = 208.5 lbs in 200 feet of 1-3/4" hose

    Weight Difference of water = 208.5 - 153.2 = 55.3 lbs

    Note the Density of water at 50 F is 62.4 lbs/ft. It varies slightly with temperature changes.

    I prefer the equation: WD = 17(D^2 - d^2) to determine the Weight Difference.

    If I made a mistake, please let me know.

  11. #31
    Senior Member upinflames60's Avatar
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    Default automatic nozzle

    If you have the right size automatic nozzle you should use an 1-3/4" hose. Alot of fire can be put out with this combo but be careful because you'll drain your truck fast if your not.
    Burgess Wills
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  12. #32
    Senior Member Dalmatian90's Avatar
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    FYI on the numbers...or "let's talk about the physics of the situation"

    The "perceived" increase in difficulty will probably be more than the raw weight gain alone.

    Because that weight is distributed along the length of the hose, and it's not only more weight for you to pull, but it will cause more friction along the entire length of the hose (more weight pushing the hose against the floor more "firmly" if you will).

    If we guess at normal hose on a carpeted floor being roughly equivelant to wood sliding on wood, it's a 50% factor. If you're horribly unlucky and have rubber-jacketed hose on dry concrete, it's a 100% factor. i.e. those 55 extra pounds will probably feel like 75 or 80 extra pounds when you're actually pulling the line due to friction.

    Which is why some of the premium attack lines, like Angus Hi-Combat, tout their "slipperier" jackets -- less friction on the jacket, the easier it is to pull.

    Of course, this is a complicated situation to model, because other things can make your pulling on the hose hard, such as having to pull it through one or more tight turns. People may complain about higher pressures in line (150, 200psi) being more difficult to handle, but on the flip side those might be easier to pull since they'd kink less on corners.

    Just food for thought
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  13. #33
    Forum Member FyredUp's Avatar
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    upinflames60...

    The RIGHT automatic nozzle? Well, some may argue there is no such thing, but for the sake of argument the type of nozzle is irrelevant. It is the flow capability of the nozzle and not the type of nozzle that matters. A single gallonage nozzle that flows 150 gpm or more, a low pressure nozzle that flows 150 or more at 50-75 psi, or even a smoothbore of 7/8" or greater is also a very good choice for 1 3/4" hose. Any nozzle capable of a flow in the range of 150-200 gpm is an appropriate choice.

    FyredUp

  14. #34
    Forum Member EastKyFF's Avatar
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    Whoopsie-doo on my math!! Thanks for the correction...forgot that convert-cubic-feet-to-gallons step. That was a big difference.
    "Be polite, be professional, but have a plan to kill everybody you meet.”
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  15. #35
    MembersZone Subscriber dmleblanc's Avatar
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    I feel that it would be an asset to the department, but the union feels that it is to heavy and that 1-1/2 hose is sufficient for our purpose
    Lord knows I don't want to start a union/non-union debate here, but anyone see a problem with this statement? No calculations, no scientific approach, no "let's try it out and see how it works". The union don't like it, end of discussion. "200 years of tradition unimpeded by progress". Indeed.

    That being said, we phased out most of our 1.5" a long time ago. Been using 1.75" as our primary attack line for almost as long as I've been with the department, with 1.75" nozzles of course. I like the increased volume and I don't think it's that difficult to handle, even for an out-of-shape slug like me. Really, for anyone who's been in our department under 15 years or so, 1.75" is what fire hose is supposed to feel like. They've never even used 1.5". Maybe if we tried 2" they'd complain, but 1.75" is what they "grew up" with.

    I'm sure the first guy who suggested we should quit using booster reels got much the same reception.

  16. #36
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    Dalmatian90, you have raised some good points. Although the initial post seemed to be interested primarily in the weight issue, a comparison between a 1-1/2" and 1-3/4" hose includes an analysis of several factors:
    1. Hydraulics
    2. Logistics
    3, Cost

    Regarding hydraulics, one must consider the desired flow rate. If one desires 200 gpm, the 1-1/2" quickly becomes impractical. If 125 gpm is needed, the 1-1/2" is a viable option. Also, if larger flows are needed, what are the nozzle reaction forces (fog vs, smooth bore).

    Logistics include (1) storing it on the engine and (2) maneuvering the hose line.

    (1) If you currently have 200 feet of preconnected 1-1/2", can you accommodate 200 feet of 1-3/4" in the same space?)

    (2) Maneuvering the hose involves several issues:
    (A) Weight - This has been covered in previous posts.
    (B) Kinks - How susceptible are each to kinking?
    (C) Nozzle reaction forces. This varies with fog nozzles (50, 75, 100 psi) and smooth bore nozzles of various diameters.
    (D) Manpower - Does the 1-3/4" line require more manpower?

    The weight issue involves not only a vertical lift, but also friction forces. Seldom does one have to lift (vertically) 200 ft of hose. Also, seldom does one have to drag the entire length of a charged 200 ft preconnect. The last 50 to 100 ft of the hose is typically what has to be dragged. The frictional resistance is based on the coefficient of friction (which is what Dalmatian90 was describing) and the weight of the object - not the surface area. Pulling a hose line up the stairs involves overcoming friction forces and the vertical weight.

    Cost: Looking at the cost of 1-1/2" versus 1-3/4" I found a cost difference of $10 to $15. I am sure with the number of distributors available, there are other values.

    All of this requires some number crunching based on what is available t oyour department.

    There is probably something I forgot, so add to the list.

    Dalmatian90, you’re dissertation on fire development is very interesting and I would encourage you to start a new thread on the subject.

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