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  1. #41
    Forum Member FyredUp's Avatar
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    pfd4life....

    Don't put too much faith in the dual pressure nozzles. Remember it is still an automatic nozzle and still needs pressure to open the stem to let water flow. Depending on when you bought them and what model you have they still need eother 50 or 75 psi in order to open up.

    I watched a demonstration of one of these nozzles in a simulation of a pressure reduced standpipe. The pressure at the wye was 45 psi and the hose length was 100 feet of 1 3/4 inch. Initially the nozzle was left at standard pressure and the flow was an amazing 13 gpm. The reach was about 60 feet or so. The nozzle was then turned to low pressure and the flow went up to...are you ready for this? The flow went up to 14 gpm, that's right it gained 1 gpm by going to low flow.

    Depends on your target flow what size of smoothbore to use. My favorites are 7/8" for 160 gpm at 50 psi or 15/16" for 182 at 50 psi.

    Good luck, believe me there are some that voodoo and tradition will outweigh science and hydraulics.

    FyredUp


  2. #42
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    My departments preconnects are 200ft, 1 3/4. 550 to 750ft is way to much for an attack line. Our skid load doesn't even have 750ft of hose. The skid (two handlines 150ft each with a wye and 450ft of 3in). How do they plan to pull a 750ft attack line off the rig? Also friction loss would be a consideration when having to charge the 750ft line to correct nozzle pressure.

  3. #43
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    Quote Originally Posted by remembering911
    My departments preconnects are 200ft, 1 3/4. 550 to 750ft is way to much for an attack line. Our skid load doesn't even have 750ft of hose. The skid (two handlines 150ft each with a wye and 450ft of 3in).
    Just a question what if you need more than 600ft? What if you backstretch from the hydrant?

    How do they plan to pull a 750ft attack line off the rig? Also friction loss would be a consideration when having to charge the 750ft line to correct nozzle pressure.
    It shouldn't be hard...as long as one uses a smoothbore one can easily pump 16 lengths(No more than 6-1 3/4" lengths) up 6-7 flights at 250 psi at the pump. I don't know too many rigs that can't do that.

    FTM-PTB

  4. #44
    Forum Member Dave1983's Avatar
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    Quote Originally Posted by pfd4life
    I agree, though my departmetn will never change as long as current management stays in place. Another question for you, as you seem to be good with quick calcs. I looked over our pump chart again, we are supposed to pump 155psi on our 250ft 1.75 lines with a standard 100psi TFT automatic. We would still be underpumping the line/nozzle combo correct?
    At 155psi on a 250' 1 3/4" line with TFT nozzle, your flow would be around 115 GPM (figured on nearest 5 GPM). That does not include condition of your hose and nozzle, or friction loss in your piping. You may be + or - a few GPMs.

    I get this number right from TFTs own flow chart I printed out from their website a couple years ago. According to TFTs own numbers, you cannot get the full 200GPM with that length of line. The chart shows a max of 195 GPM, and thats at 250 psi engine pressure.

    I got the chart after continued debates with my own Opps Chief over our SOGs for pump pressures. I kept telling him the numbers were wrong (my Akron Fire Calc told me so). He didnt belive me till I handed him a copie of the chart.
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  5. #45
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    Just a few comments in regards to the initial post...

    If you are using 1 1/2 hose I'll just assume it's double cotton jacket hose w/ rubber liner. If that's the case, and say the target GPM is a mere 125 GPM, that would equate to about 45 PSI of FL per 100'.

    750' of 1 1/2 is around 335 PSI for the FL plus 100 PSI for those lovely fog nozzles.

    I could understand having a static hosebed of that amount of 1 3/4 hose, assuming the response area won't commonly or hardly ever stretch beyond 300'. But using 1 1/2 and having 750' PRECONNECTED makes no sense.

    BTW, discussing friction loss numbers can be tough considering the number of differnt types of hoses out there today. My dept may factor 40 PSI per 100' for 180 GPM (1 3/4) with our hose, but somebody with some high dollar Angus hose may need to factor a lot less. But either way, get your hands on an inline pressure gauge and do a little math, and there won't be a need to consult 20 different charts anymore.

  6. #46
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    Quote Originally Posted by Dave1983
    At 155psi on a 250' 1 3/4" line with TFT nozzle, your flow would be around 115 GPM (figured on nearest 5 GPM). That does not include condition of your hose and nozzle, or friction loss in your piping. You may be + or - a few GPMs.

    I get this number right from TFTs own flow chart I printed out from their website a couple years ago. According to TFTs own numbers, you cannot get the full 200GPM with that length of line. The chart shows a max of 195 GPM, and thats at 250 psi engine pressure.

    I got the chart after continued debates with my own Opps Chief over our SOGs for pump pressures. I kept telling him the numbers were wrong (my Akron Fire Calc told me so). He didnt belive me till I handed him a copie of the chart.
    Just to add onto my last post, what really only matters as for the friction loss is the hose construction and size. Your EP will be much different in your senarios if you were using 1 3/4" cotton hose from 1970 compared to some Angus "1 3/4" that actually probably expands internally close to 2". Thermo plastic urethane, synthetic rubbers, all that fancy liner stuff I don't know a whole lot about I'm sure plays a big factor. But the nozzle should have no real impact on the FL assuming equal GPM and desired NP. Like others have said, flow testing puts all this theory/speculation to rest.

  7. #47
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    I've gone over our pump chart AGAIN. We are figuring in 22psi/100ft for the FL, at 155psi EP, it makes exactly 55psi for the FL, for 100psi on the knob. GPM is "supposed" to be 150gpm. It makes a bit more sense now, though I still think it's off.
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  8. #48
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    Quote Originally Posted by pfd4life
    I've gone over our pump chart AGAIN. We are figuring in 22psi/100ft for the FL, at 155psi EP, it makes exactly 55psi for the FL, for 100psi on the knob. GPM is "supposed" to be 150gpm. It makes a bit more sense now, though I still think it's off.
    What brand/model attack line are you using on that line and where is your pump pressure chart from? You may be able to get an accurate chart from the hose manufacture. I know that with our attack line, we figure 30 PSI per 100' on 1 3/4" hose at 150 GPM.

  9. #49
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    Default 2 1/2

    At my department all commercial fires are fought with a 2 1/2. More water the better and two people can handle it if your pump man knows what he is doing. 1 1/2 should be banned execpt for a trash line. 1 3/4 is used for room and contents.

  10. #50
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    The department I work for requires all 33 engine companies be equipped with a 350' preconnect 1-1/2". My company runs a 400', and we extend it often with 100' (standpipe) rack. Our SOG's are set up that 4 of the 5 engines on a box alarm assignment initially run an 1-1/2" preconnect (length between 150-400 ft.). So if we are supplying another company from a hydrant, we will also run an 1-1/2" preconnect from our own piece to the fire building/exposure(usually 250 or 400). One of the reasons for this is to avoid a potential problem if one of the engines has mechanical difficulties while pumping and may need to shut down. That way we still have other water sources available. It works well for us.

  11. #51
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    Quote Originally Posted by DCwagondriver
    The department I work for requires all 33 engine companies be equipped with a 350' preconnect 1-1/2". My company runs a 400', and we extend it often with 100' (standpipe) rack. Our SOG's are set up that 4 of the 5 engines on a box alarm assignment initially run an 1-1/2" preconnect (length between 150-400 ft.). So if we are supplying another company from a hydrant, we will also run an 1-1/2" preconnect from our own piece to the fire building/exposure(usually 250 or 400). One of the reasons for this is to avoid a potential problem if one of the engines has mechanical difficulties while pumping and may need to shut down. That way we still have other water sources available. It works well for us.
    Just curious, what type of nozzles and what is the intended GPM for the 1 1/2"s? Also, do your engines have 2 stages pump (set on pressure/series) or just a single stage?

  12. #52
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    erics99,
    We use Akron break-away style 125gpm nozzles (excellent for extending the line).They have a fog tip that can be taken off to give us a 15/16 smoothbore. I think everybody keeps the fog tip on, but having a smooth bore option is nice. Also, if we would run into the problem of a high pump pressure, we could take the fog tip off to reduce our pump pressure. And yes, we have 2 stage pumps, so that definitely helps.

  13. #53
    Forum Member FyredUp's Avatar
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    DCwagondriver...

    In order for you to flow 125 gpm out to 350 feet to a 100 psi combo nozzle you need to pump it at 230 psi. To go 400 feet you need to pump it at 250 psi.

    There is no way you can supply that 15/16 smoothbore to flow its 182 gpm out to either one of those lengths. For 350 feet the pump pressure would be 328 psi and for 400 feet it would be 368 psi.

    While the 125 gpm flow with the combo nozzle is possible, the 182 gpm flow is not, unless you are using high pressure hose.

    So my guess is either you are mistaken on the hose size or the nozzle size for the smooth bore.

    The reality is 1 3/4 would do this and more at less pump pressure.

    FyredUp

  14. #54
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    Our dept. figures for our combo nozzles - 100 psi (for tip) + 30 psi per 100' of 1-1/2" hose.
    Our max pump pressure per dept. SOP's is 300psi.
    It's 1-1/2" hose and it's a 15/16. Hardly any experience with taking off the fog tip and using smooth bore. Did it twice on our 150' 1-1/2" crosslays. Guess we'll keep the fog tip on the 400' all the time. Thank you for your advice.

  15. #55
    55 Years & Still Rolling hwoods's Avatar
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    Thumbs up Well..........

    I understand where DCWagondriver is coming from, and I know that the operation that he outlined is the way it is done in his department. My VFD runs a 1.5 up to 400 feet with no problems. At work, I have run a 1 inch line that hit an even 1,000 feet, and operated for several hours with no problem. This is an area of Firefighting where every jurisdiction seems to have different rules.
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  16. #56
    Forum Member Dave1983's Avatar
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    I dont doubt whats being said here, although, IMHO, 125gpm isnt an acceptable flow for an attack line. My question is, why do you want to subject your apparatus to thoese kinds of pump pressures on a regular basis?
    It cant be good for them. Why would you want to use the upper limits as SOG?

    The only time we come anywere close to thoese kinds of pressure numbers is when we are flowing foam.

    It just doesnt make amy sense to me. I wonder, do you operate other equipment at maximum tollerence on a daily basis as well?
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  17. #57
    55 Years & Still Rolling hwoods's Avatar
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    Lightbulb Well.............

    Dave raises some good points, and I don't have the answers, except that the thousand foot stretch of 1 inch is not a misprint. Our rigs at work (work is Md. DNR Forest Service) are constructed a bit different, in that I am flowing about 20 GPM on that 1 inch, and the pump normally operates at 285 PSI, and can be jacked up to 400 max. The Max flow is supposed to be 100 GPM @ 100 PSI, but I've got my rig delivering 125 @ 100 PSI, using a 2.5 Suction Sleeve in place of the 1.5 that the pump was delivered with.
    Never use Force! Get a Bigger Hammer.
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  18. #58
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    Talking

    Weel you have to realize that your pumper is not doing all that work. In DC where I work we operate with 2 wagons, one on the fire ground and one on the hydrant. The wagons SOP's at hydrant are to pump 125psi ( or 150psi if using the anchor "Hydrant valve") So 125psi ,the hydrant probably has a pressure of at least 50psi, and they are 300' away so add about 27psi for FL So this pumper is only pumping 102psi. Now the Wagon at the fire lets say he is operating 2 crosslays @ (200' 1-1/2" thats 125 GPM each) 160psi but he is receving 125psifrom the first pumper. So this wagon is only pumping 30psi. You must remember that these pumps take advantage of incoming pressure so the actual work the pump does is less.

  19. #59
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    DCHydroEngineer...

    Of course the attack pumper takes advantage of the supply pumpers boost in pressure. Just as the attack pumper would do the same off from a good hydrant without a supply pumper.

    BUT, the facts still remain that in order to flow the water you say you are flowing the engine pressure from the second engine has to be close to what I posted above. For the 350 and 400 foot 1 1/2 inch lines it is virtually impossible to flow those gpms for the 15/16 inch nozzle unless your hose is rated at a minimum of 400 psi working pressures.

    For 1 3/4 inch hose the EP would still have to be around 255 psi for 400 feet.

    My career FD uses 1 3/4 inch hose for a 200 gpm at 75 psi break a part nozzle with the 15/15 inch tip. If we go beyond the 300 foot preconnect we go to a 2 1/2 inch line with a wye to reduce friction loss.

    My volly FD uses 2 inch hose with the same 200 at 75 combo tip, but our smoothbore is a 1 1/4 inch. If we go beyond our 300 foot preconnects we stretch a 3 inch line with a wye to reduce friction loss.

    I am not saying what you do doesn't worj for you. You know that better than I do, I am not there. I am saying there are easier ways to get there.

    FyredUp

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    You can do it the way DCHydro. is talking about at a lower pressure. Because like he said that 2nd wagon can open his lines and be flowing at 107psi or whatever number he quoted while just at idle. So he can boost that pressure by 150psi and not be running his truck very hard. By the 2nd wagon having that high of an incoming pressure it allows him to pump at that higher pressure, and have his engine working just like it would with 200' of hose on the ground. We used to have to boost pressure all the time when we used 3'' as supply line, but now we drop 5'' and don't have to worry about it.

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