1. #1
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    Default High Pump Discharge Pressures

    In multiple posts many people claim very high flows from 1 3/4 or 1 1/2 lines, with high PDP. At what point do you feel uncomfortable with pumping the line? Is it 250 psi, 300 psi, higher?

    What precautions do you take to prevent injury if the line blows? Is it realy practical to flow 250 gpm from a 1 3/4 line or would a 2.5" be better?

    What about the capabilities of the engine itself? At 250 psi you can only get about 1/2 capacity, is that a concern of yours.

    I'd like to hear your comments.

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    Is it really practical?- NO. Sometimes people see a number and know they can reach it without thinking of the consequenses of their actions. To get 250gpm out of a 1 3/4 for a 200 ft attack line you would have to have the PDP at 294psi. The capacity of a mid-ship pump diminishes greatly when you exceed 150 psi, would you have anything left over to give an additional line if needed, let alone the stress on the apparatus as a whole - Why would anyone do this???? As you said lay a 2 1/2 if you need excessive flows, there are those that will argue on the ability to move a 1 3/4 vs the a 2 1/2 but with the reaction force of the 1 3/4 will pin you to the walls.

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    It depends on your hose. Normally on the standard 1 3/4" lines it is impractical to try for 250 gpm, and I would recommend a 2 1/2" line. But we have found that Conquest hose will allow us larger flows on our 1 3/4" pre-connects. For example one of our 2 pre-connects is 200' of 1 3/4" with a stack tip of 1" & 1 1/8" Smooth Bore nozzles. With the 1" we are getting 200 gpm with a PDP of 110 psi. With the 1 1/8" we are getting 250 gpm with a PDP of 150 psi. That is a fine line of deciding to change to 2 1/2" but it works great with this hose. It gives us options and versatility. The other two preconnects: #1 - 200' of Conquest 1 3/4" with TFT-Automatic Fog, PDP of 130 psi. #3 - 200' of 2.5" with Stack tips 1 1/8" & 1 1/4" Smooth Bore PDP of 75 psi and 95 psi respectively. This set up works very well for us.
    Firefighter/Paramedic Ron Sanders
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    This is simply my opinion and does not represent the opinion or view of my employer(s) or any department/agency to which I belong.

    Personal Website: http://RonSanders.Biz Check it Out!

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    fireman387, I would like to address some of your concerns.

    When you talk about diminished pump capacity when exceeding 150 psi pdp your are taliking about a net engine pressure. Pumps are rated to net engine pressure wich is done at draft. When you hook up to a hydrant which is a positive incoming pressure the net pressure is assisted by the hydrant pressure to develope the overall ep. Net ep is developed totally by the horsepower of the fire truck powerplant. Example, using your ep of 294 psi lets say that your incoming hydrant pressure was 80 psi. 294 minus 80 equals 214 which is your net engine pressure.

    Nozzle reaction is created from nozzle pressure and gpm. Hose size does not enter into the equation. A 1-3/4" line vs a 2-1/2" line at the same flow will feel harder to handle only because of the smaller diameter line not having as much surface contact to the ground.

    An 1-3/4" line can be handled just as easy as a 2-1/2" line with the proper handling techniques. With a limited crew and a difficult stretch I would rather pull a 250 gpm 1-3/4" line any day.

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    You would rather use an 1 3/4 inch line flowing 250 gpm than a 2 1/2 with the same gpm with a difficult lead? I wouldn't.

    The 1 3/4 line was developed for mobility first, and greater gpm than 1 1/2 line. I am talking about mobility inside of compartmentalized structures, which make up the majority of our fires. Flowing 250 gpm from an 1 3/4 line takes away the mobility advantages afforded by using the line. You will ahve great difficulty trying to flow and move at the same time with that gpm. Particularly with difficult leads created by multiple floors and stairs. If mobility is not an use, flow what you want.

    This is assuming you are using the traditional 7/8 or 15/16 tips. If you are talking about 1 1/8 or 1 1/4 things will feel differently. But at that point you might as well take the tip off and put your thumb over the end of the open butt.

    If you have to flow large amounts of water use mulitple small lines working in conjunction with eachother, or larger diameter hose with less reation.

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    staylow, remember I said limited crew. Your talk of multiple small streams to make up the flow requires more then limited crew. Th 2-1/2" advancing as you suggest also would require a few people. I am only talking about using the 1-3/4" line when the help is not there. And I say again with the proper handling techniques it is fairly easy. I will send you some info that talks about how this is done.

    Oh yea how is you new chief Mario doing?

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    Thanks for the offer of the hanline techniques, but I won't need them here. They would not fit our system.

    As far as the new chief, I hear he is still trying to figure out how he'd get to the ocean from the center of the city

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    staylow, good luck and remember. The mind is like a parachute. It works best when it's open!!

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    Big Paulie, you are correct if you are connected to a hydrant, what if you are relaying water, or in a rural setting you are having to use a dump tank now you are back to square one.

    Nozzle reaction does not have to do with hose size, but rather the gpm's at a given psi. I used line sizes for a illustration.

    Something that no one has brought up by now; what do you service test a hose line on your apparatus to?? 250psi Why would you exceed that??

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    minimum anual test pressure for any municpal
    hose that I am aware of is 300psi. Most
    1-1/2", 1-3/4", 2", 2-1/2" and 3" has a service test pressure of 400 psi. You can choose to test it at a lower pressure but that limits the maximum operating pressure.

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    IFSTA, NFPA, and manufacturers say that the maximum allowed operating pressure shall be no higher than 10% less then the anual test pressure. 10% less then 400 is 360 psi. I have found through flow tests that pressures higher then 300 psi are really not worth the effort because of the minimal amount of flow gain due to critical velocity. however if the pressure requirements are needed such as for a highrise then it can be done.

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    ADSN/WFLD

    At what point do you feel uncomfortable with pumping the line? Is it 250 psi, 300 psi, higher?

    Generally anything above 250psi PDP. Not so much for the line pressure though as the RPMs. The apparatus might be able to take it, but just something about the way it screams makes me nervous.

    What precautions do you take to prevent injury if the line blows?

    Full PPE is required. Also, test the hose annually.

    Is it realy practical to flow 250 gpm from a 1 3/4 line or would a 2.5" be better?

    Yes it is really practical to flow 250gpm from the 1.75", and no the 2.5" wouldn't be easier, just heavier and less mobile.

    If it wasn't, NFPA would say don't do it as well as the hose and nozzle manufacturers. As it is, to my knowledge NFPA doesn't address the issue and the hose and nozzle mfgs say go for it.

    What about the capabilities of the engine itself? At 250 psi you can only get about 1/2 capacity, is that a concern of yours.

    No, it is not a concern. A 1500gpm engine flowing 250psi flows 750gpm. If you need to be flowing more than 750gpm, you might want to do it through something besides multiple 1.75" lines.

    I'd like to hear your comments.

    My last comment is a question - Have you ever tried it to make up your own mind?

    fireman_387

    To get 250gpm out of a 1 3/4 for a 200 ft attack line you would have to have the PDP at 294psi.

    I'd like to know where you get your numbers.

    We use Elkhart SM-30s with N-Dura hose and they're nowhere near that.

    250gpm through 150' of 1.75" = 200psi PDP
    250gpm through 200' of 1.75" = 230psi PDP
    250gpm through 200' of 2" = 180psi PDP
    300gpm through 200' of 2" = 230psi PDP

    As you said lay a 2 1/2 if you need excessive flows,

    Agreed, anything over 325gpm should come out of a 2.5". It's only 250psi PDP for the 2" with an SM-30.

    there are those that will argue on the ability to move a 1 3/4 vs the a 2 1/2 but with the reaction force of the 1 3/4 will pin you to the walls.

    Or, just pin it to the ground.

    onycs

    It depends on your hose. Normally on the standard 1 3/4" lines it is impractical to try for 250 gpm, and I would recommend a 2 1/2" line.

    We use do it with N-Dura on one dept and PonnConquest on another.

    Staylow

    Flowing 250 gpm from an 1 3/4 line takes away the mobility advantages afforded by using the line.

    Not to the extenet the 2.5" does. The 1.75" flowing 250gpm is still more mobile than the 2.5".

    They would not fit our system.

    We didn't think they'd fit our system either. What a shock when we said those techniques won't work here, but we tried it and it did.

    Some guys still don't believe they'll work. Another case of seeing something work in practice and wondering if it will work in theory.

    fireman_387

    or in a rural setting you are having to use a dump tank now you are back to square one.

    Works fine in the rural setting, at draft, nursing or straight off the tank.

    Something that no one has brought up by now; what do you service test a hose line on your apparatus to?? 250psi Why would you exceed that??

    Service test it to mfg requirements.

    One last thing...

    We use hi flows on handlines are quick hit "get control" flows with limited manpower. Once knockdown is achieved, reduce the pressure and finish the job, no need to go back and drag off the smaller line just to have the fire get ahead of you while you do that. After knockdown, who wants to drag around a 2.5" when all you need is 150gpm?

    But then again, things are probably way different where you guys are. We only deal with 1, 2 and 3 story new, old and historical homes, both closely packed and spread out, shopping centers, trailer parks, malls, resturaunts, airport, manufacturing facilities and (today) our tallest building is 10 stories.

    [ 07-08-2001: Message edited by: mongofire_99 ]
    It's only my opinion. I do not speak for any group or organization I belong to or associate with or people I know - especially my employer. If you like it, we can share it, you don't have to give me credit. If you don't, we are allowed to disagree too (but be ready to be challenged, you may be on to something I'm not). That's what makes America great!

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    mongofire, Good post however I will disagree on one point. Engine governors limit the RPM's The manufacturer will make sure that the rpms are not too high with this device. yes it does sound hairy when the engine screams but not to worry, they designed for this. Check out Rpm's when doing the anual pump test or for that matter when driving down the road at 55 mph.

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    BIG PAULIE

    yes it does sound hairy when the engine screams but not to worry, they designed for this.

    Point taken. I should have said "The apparatus can take it, but..."

    Some of our disbelievers to this day still spout the following mantra from days gone by:

    0.75" line - 75gpm
    1.00" line - 100gpm
    1.50" line - 150gpm
    1.75" line - 175gpm
    2.00" line - 200gpm
    2.50" line - 250gpm
    3.00" line - 300gpm

    (I see a pattern here, good thing they don't follow it on supply lines with BS like:

    4" LDH - 400gpm
    5" LDH - 500gpm)

    Some food for thought...

    Consider the typical house fire (say 1,500sq. ft.) with heavy to full involvement. Looking at your rate of flow formulas that we all base our flows on (right?...), what do we really have in this situation?

    A) A single fire that needs 500gpm delivered in 30 seconds to extinguish?

    B) Several 'compartment' fires of anywhere between 110sq ft., needing 36gpm (bathroom) to 500sq. ft. or more needing at least 210gpm (combined kitchen/dining/living room).

    If the fire is A, then by all means, go at at it with at least a 2.5" line.

    But!

    If the fire is B, then what sense does it make to go after it with a 2.5" line when the 1.75" or 2" flowing 250gpm will get us quick control of the point of entry fire (say the combined kitchen/dining/living room)?

    Knock that down then reduce the pressure/flow, get in and put out the rest - bedrooms (~200 sq. ft, 67gpm) and bathrooms.

    Or, the typical manufactured home...

    14 X 80 = 1,120 sq. ft. = 375gpm fully involved.

    Again, are we looking at single a 375gpm fire or mutliple smaller compartmentalized fires?

    Ever take a 2.5" line in a mobile home?

    [ 07-08-2001: Message edited by: mongofire_99 ]
    It's only my opinion. I do not speak for any group or organization I belong to or associate with or people I know - especially my employer. If you like it, we can share it, you don't have to give me credit. If you don't, we are allowed to disagree too (but be ready to be challenged, you may be on to something I'm not). That's what makes America great!

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    Have you ever tried it to make up your own mind?
    A little harsh aren't we? I amost always have an opinion formed, but I've found that it is good to keep an open mind.

    In our area almost everyone flows the traditional pressures and flows, 95 for 1 1/2, 150 for 1.75 amd 250 to 300 for 2.5". Only recently with the introduction of the Vindicator have firefighters started to accept that you can get higher flows in a controllable line. and now people are starting to look at other devices for the higher flows.

    I personally like the idea of keeping pressures at or below 150 psi. While we usually don't pump capacity we try to keep our options open just in case.
    Some of the departments, including my own, are still big fans of larger hose (3") wyed into the smaller handlines in an effort to keep the pressure down.
    As an example a 1 3/4 line 150' with a 15/16 sb (about 50 per 100) with 800' of 3" can be pumped at 145 psi. Put the second line in service and you can pump it with 210 psi. 60 psi hydrant and we are at 150 again.
    In our area we can get to any hydrant with 800' (reverse lay)
    This gives us decent flows and we don't have the need for tankers or even relays.

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    A little harsh aren't we?

    No, just direct.

    Have you?

    In our area almost everyone flows the traditional pressures and flows, 95 for 1 1/2, 150 for 1.75 amd 250 to 300 for 2.5".

    Yeah, we've still got some knotheads like that too.

    Only recently with the introduction of the Vindicator have firefighters started to accept that you can get higher flows in a controllable line.

    The vindicator may do all that it's touted to do and if it took that to get people to wake up, that's one thing. But for the last several years, published articles and posts here by Shapiro and others told us these things were easy and doable. Depending on what old nozzles you had, you may have very well wasted $700 a copy on your new nozzles.

    and now people are starting to look at other devices for the higher flows.

    GREAT! BlitzFire, the Big Paulie nozzle, SM-30, Akromatics, TFT Handlines, even the smoothbores you currently underpump will give you higher flows.

    As an example a 1 3/4 line 150' with a 15/16 sb (about 50 per 100) with 800' of 3" can be pumped at 145 psi.

    Want to keep the pressure down, cut the wyed lines to 100' of 1.75". Lay a 3" to the door, 100' ought to get anywhere in a house you want to go. For that matter (in our case, might apply there too) 50' from the door gets the job done in most cases.
    It's only my opinion. I do not speak for any group or organization I belong to or associate with or people I know - especially my employer. If you like it, we can share it, you don't have to give me credit. If you don't, we are allowed to disagree too (but be ready to be challenged, you may be on to something I'm not). That's what makes America great!

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    Here is my $.02-

    Here at home we have sop's of 120-150psi on 200'1.75 lines-anything needing a flow above that generally gets a 2.5(same pressure),we try to keep it simple and safe.

    hope this helps!!!

    [ 07-14-2001: Message edited by: 911-WACKER ]
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    We test our hose at 250 for 5 min and 300 for 2 min.Over a period of time we found that the 300/two min. test will show up a marginal hose where the 250 won't.This has paid off on the fire ground on occasions when systems for one reason or another get pushed just a little.Plus it gives you just a little safety edge on the fireground.Just my opinion.T.C.

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    here are some key point i think should be brought up
    1st a sb handline should have 50 psi nozzle pressure
    and a tft automatic needs 100 psi nozzle pressure to operate correctly
    2nd a 15/16" tip is the larges tip you should use on a 1 3/4" hose
    a 15/16" tip at 50 psi nozzle pressure will flow 185gpm and with 1 3/4" hose that is 53psi friction loss per 100' of hose so a 200' preconnect pdp would be 153 psi

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    911-WACKER

    Here at home we have sop's of 120-150psi on 200'1.75 lines-anything needing a flow above that generally gets a 2.5

    What are your SOPs for the 2.5".

    we try to keep it simple and safe.

    So does everyone else posting here, including those of us advocating higher flows and pressures.

    Rescue 101

    we found that the 300/two min. test will show up a marginal hose where the 250 won't.

    Good going!

    cubby

    sb handline should have 50 psi nozzle pressure

    Why?

    If it's on a master stream it gets 80psi.

    What's the difference if it's on a master stream or a ball valve? Too hard to hold?

    and a tft automatic needs 100 psi nozzle pressure to operate correctly

    Or 75psi or ~50psi. Some autos and fixed flows only need 50psi. TFTs web site says in the LP mode their nozzles "pressure is reduced by about 50%..."

    a 15/16" tip at 50 psi nozzle pressure will flow 185gpm

    At 80psi it would be 233gpm.
    It's only my opinion. I do not speak for any group or organization I belong to or associate with or people I know - especially my employer. If you like it, we can share it, you don't have to give me credit. If you don't, we are allowed to disagree too (but be ready to be challenged, you may be on to something I'm not). That's what makes America great!

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    Mongo, where I got that from is the friction loss formula from the ifsta manual on pumping apparatus.

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    ...friction loss formula from the ifsta manual on pumping apparatus.

    Thanks.

    More proof in the pudding that the books are not (and to be fair, maybe cannot be) kept up to date with current technology, at least as it relates to FL.

    Sure it's nice to have a generic guideline. But, especially in this case, it is easy to see how these guidelines may be hold us back.

    64psi is a huge difference in FL. For the hose and nozzle combo we use, 294psi would give us 300gpm out of 200' of 1.75".

    To paraphrase what Big Paulies says, 'challenge the books, but don't go outside mfg specs.'

    It's interesting to remember (for me anyway) that regarding science in general, just 100 years ago it was thought everything that could be learned had been. Since that time, we've developed powered flight and been to the moon and back.
    It's only my opinion. I do not speak for any group or organization I belong to or associate with or people I know - especially my employer. If you like it, we can share it, you don't have to give me credit. If you don't, we are allowed to disagree too (but be ready to be challenged, you may be on to something I'm not). That's what makes America great!

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    THing to remember Mongo is that not everyone has the up to date technology

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    Yeah, but I'd be willing to bet that what everybody has out perfoms the books.
    It's only my opinion. I do not speak for any group or organization I belong to or associate with or people I know - especially my employer. If you like it, we can share it, you don't have to give me credit. If you don't, we are allowed to disagree too (but be ready to be challenged, you may be on to something I'm not). That's what makes America great!

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    Mongo, if you have noticed the newest IFSTA book Pumping Apparatus Driver/Operator Handbook 1st ed has changed the way we calculate theoretical FL. The reason stated is because of advances in technology causing lower FL. They also dropped FL in appliances flowing under 350 gpm.
    I think IFSTA has done a good job in trying to keep up with technology. Aside from that IFSTA recommeds that you calculate your own hose's FL.

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