1. #26
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    Let's do the math

    1970:

    1000gpm pump two-stage in volume mode, laying dual 3" double jacket rubber lined hose: Delivers full volume @ 650'.

    2007:
    1500gpm pump, single stage, laying 5" Angus Hi-Vol: Delivers full volume @ 1,700'.

    If you hydrants are spaced at 500' apart and can deliver 2000gpm+ each, in 1970 you would've needed to dual pump to deliver full volume or used three pumpers -- one on the first, and one on the second with another pumper in relay.

    Today, you just lay 500' more 5" hose and it has no effect on the number of pumpers or volume of water delivered.

    If you really want to play math games...the 2007 scenario is delivering 3,000gpm. To get that out of the 1970 era pumpers & hose...you'd need a total of 6 pumpers and 3 hydrants -- 1 pumper on a hydrant "A" with 500' to the fireground, 1 pumper on hydrant "B" 1000' from fireground + 1 relay pumper , and 1 pumper on hydrant "C" 1500' from the fireground + 2 relay pumpers 1500' from the fireground.

    So the utility of the dual pumping is a lot less today then it was in the past -- there's better technology today to achieve the same goal with less complexity.

    Whether it's something that's a practical situation for your area is something to be figured out locally -- I'm sure there's still the oddball situation for it. There isn't any in my town though -- no hydrants deliver more than 1,500gpm.

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    We used this a couple months ago. and for trotter some day you might want to use this... 4" from Hydrant to the steamer intake of #1 engine. this engine has a 1 3/4 line off so it, engine one is not using a lot of water. Now we ran a 4" from another intake of #1 engine to the steamer intake of a second engine around the corner, which had 2, 1 3/4 lines off of it.... Notice it is intake to intake, not discharges.. The pressure is not boosted to the second engine by the first, it is only using the extra (residual) pressure from the hydrant that the #1 engine is not using and diverting it to the #2 engine for its use. It works well if you only have 1 Hydrant for a specific area. In this case it was a couple trailers off with 3 exposers... The hydrant had great water but a 600' lay was required to reach the back of the trailer court...This is common up here because trailer courts have private hydrants and in this case had no hydrants because the owners didn't want to spend the money in the 70's for a system... It is another choice the pump operator has in his book for water supply... Duluth accross the bridge has about 100 psi or more from the hydrants at the bottom of the hill, they can just divert this incomming water to other engines and not have to boost the pressure. The fact is the incomming water never goes around the pumps impeller, It just backs up and out of the other intake and off to the other rig.
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    Quote Originally Posted by MemphisE34a View Post
    Having said that, no I have never done, seen it, or even heard of it being done outside of a training evolution. Its more of a nice to know than a need to know.
    We call it tandem hookup here. We had a major fire with LODD (arson, owner set his store afire) just down from the firehouse decades ago. They did end up using it there. For that reason they keep it in the hydraulics course, but as Memphis says...never seen it used in recent memory.

    It was the big excuse to continue to keep hard suctions on engines that never got anywhere near drafting except for the annual underwriters test.

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    Quote Originally Posted by Dalmatian190 View Post
    Let's do the math

    1970:

    1000gpm pump two-stage in volume mode, laying dual 3" double jacket rubber lined hose: Delivers full volume @ 650'.

    2007:
    1500gpm pump, single stage, laying 5" Angus Hi-Vol: Delivers full volume @ 1,700'.

    If you hydrants are spaced at 500' apart and can deliver 2000gpm+ each, in 1970 you would've needed to dual pump to deliver full volume or used three pumpers -- one on the first, and one on the second with another pumper in relay.

    Today, you just lay 500' more 5" hose and it has no effect on the number of pumpers or volume of water delivered.

    If you really want to play math games...the 2007 scenario is delivering 3,000gpm. To get that out of the 1970 era pumpers & hose...you'd need a total of 6 pumpers and 3 hydrants -- 1 pumper on a hydrant "A" with 500' to the fireground, 1 pumper on hydrant "B" 1000' from fireground + 1 relay pumper , and 1 pumper on hydrant "C" 1500' from the fireground + 2 relay pumpers 1500' from the fireground.

    So the utility of the dual pumping is a lot less today then it was in the past -- there's better technology today to achieve the same goal with less complexity.

    Whether it's something that's a practical situation for your area is something to be figured out locally -- I'm sure there's still the oddball situation for it. There isn't any in my town though -- no hydrants deliver more than 1,500gpm.
    Actually, we use dual pumping a lot and the only math we need to figure is whether or not the original engine that connected to the plug has water left over (we use percent drop rules of thumb on the residual pressure).

    If they have left over water than another engine can borrow water to use their own lines.

    If they do not have left over water than they have to catch a different plug...hopefully on a different main altogether.

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    Quote Originally Posted by FlyingRon View Post
    We call it tandem hookup here. We had a major fire with LODD (arson, owner set his store afire) just down from the firehouse decades ago. They did end up using it there. For that reason they keep it in the hydraulics course, but as Memphis says...never seen it used in recent memory.

    It was the big excuse to continue to keep hard suctions on engines that never got anywhere near drafting except for the annual underwriters test.
    For what I've learned as "dual pumping", their is no need for hard suction hose.

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    I guess the hard suction if #1 engine is the draft pumping to the #2 engine and #3 engine, Or else they are using hard sleeves to connect to hydrants, instead of soft suction....?????don't know Above relay pumping to a dual pumping situation??
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    It will depend on the capability of the hydrant and it's ability to deliver more water than the pumper can pump. This is the whole reason for doing flow testing on hydrants and color coding them. Doesn't make sense to hook two pumpers capable of pumping 1000 gpm to a hydrant that can supply only 1000 gpm. After all, we all know them pumpers aren't going to pull the water out of the hydrant.

    But I do have a question. Why would you use hard suction on a hydrant? If the pump can't pull the water out all you need is soft hose.

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    The only thing you are limited by is the number of discharges. A 1500 GPM pump rated at a draft can easily discharge more than that from a decent hydrant.

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    Quote Originally Posted by HotTrotter View Post
    But I do have a question. Why would you use hard suction on a hydrant? If the pump can't pull the water out all you need is soft hose.
    Hard suction (not the lightweight vacuum only stuff) was originally used because it could handle both pressure and a vacuum. Also Dual Pumping was used more often in a time when most supply lines were 2.5's. The usually 4 to 6 inch hard suction allowed the pumpers to flow the capacity of the hydrant using the steamer port. Soft suction was not as common, LDH was unheard of, and almost every pump made came with 2 sections of hard suction.

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    Trotter I am lmao... If #1 engine only needs to flow 300 gpm why not send the extra to a diffrent engine who may not have a hydrant... If you are folwing 300 gpm and still have 60 psi residual then sent it to another engine... It works well. You don't have to be in pressure/volume because the water is not going around the pump.... Murphy oil just bought a pumper with a 3000 gpm pump, Show me a hydrant that you can get that out of....Just because you have a big pump does not mean you are going to flow a max capacity all the time.... Most structure fires are put out with tank water flowing under 300 gpm.. we have 1500 gpm pumps,, so are you saying because we can flow 1500 gpm we need to flow it all the time...NO if you have left over, share the wealth... and to your 1000 gallon question is (ding ) it makes perfect sence if you don't have to flow that much... Now If you were a MPO you would learn from this and use it if needed..... Since you are not then, why don't you just learn from others who are.

    The only time this should not be used is if you are flowing deck guns, aerial devices and max flows... Then you better find hydrants on diffrent mains and call the water pump station because no one in the area will have water.
    Last edited by plisken; 05-08-2007 at 11:59 PM.
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    As for hooking hard suction to a Hydrant... It should only be used if it is tested for pressure.... Most suction is tested for vacuum..... But if you are a department without LDH/ Soft suction then you can use a section of hard suction..... It beats 2 1/2's or 3" ,, sometime better to use 6" but once again you must be close to a hydrant and it must be tested for pressure uses...... Hard suction is not used much for hydrants these days.....


    Sorry its called hard intake hose: rated for possitive pressure intake use..
    Last edited by plisken; 05-09-2007 at 12:02 AM.
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    Quote Originally Posted by jlcooke3 View Post
    Hard suction (not the lightweight vacuum only stuff) was originally used because it could handle both pressure and a vacuum. Also Dual Pumping was used more often in a time when most supply lines were 2.5's. The usually 4 to 6 inch hard suction allowed the pumpers to flow the capacity of the hydrant using the steamer port. Soft suction was not as common, LDH was unheard of, and almost every pump made came with 2 sections of hard suction.
    But pumps don't pull a vacuum. This has been discussed at length here. They only can move what the forces of nature will supply to them.

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    Quote Originally Posted by plisken View Post
    Trotter I am lmao... If #1 engine only needs to flow 300 gpm why not send the extra to a diffrent engine who may not have a hydrant... If you are folwing 300 gpm and still have 60 residual then sent it to another engine... It works well. You don't have to be in pressure/volume because the water is not going around the pump.... Murphy oil just bought a pumper with a 3000 gpm pump, Show me a hydrant that you can get that out of....Just because you have a big pump does not mean you are going to flow a max capacity all the time.... Most structure fires are put out with tank water flowing under 300 gpm.. we have 1500 gpm pumps,, so are you saying because we can flow 1500 gpm we need to flow it all the time...NO if you have left over, share the wealth... and to your 1000 gallon question is (ding ) it makes perfect sence if you don't have to flow that much... Now If you were a MPO you would learn from this and use it if needed..... Since you are not then, why don't you just learn from others who are.

    The only time this should not be used is if you are flowing deck guns, aerial devices and max flows... Then you better find hydrants on diffrent mains and call the water pump station because no one in the area will have water.
    You lost me here. If my first pumper can move 1000 gpm and it only needs 300, I hook up a second pumper to move 60 gpm?? That seems like a bit of a waste there. Especially since both pumpers need to be in close proximity to the hydrant.

    And if i have a structure fire that I an put out wit h300 gpm, then why would I need a second pumper. As long as the hydrant supplies all the water I need, and my pumper can move it, then why tie up a second truck?

    And maybe I don't know how you operate. We typically set up one pumper at the hydrant and feed a second pumper with LDH. The second pumper has 6 outlets which in most cases is all we need. If I need to flow more that 1000 gpm I need to hook t oa different hyrdant on a different feed to get the water. After all, if my hyrdrant will only give me 1000 gpm then hooking a second truck to it will be waste of a resource.

    You are really confusing me. To make effective use of your hydrants in situations where you need to use more than one you need to know how they are connected and the flows of each hydrant. Remember. These pumps can't pull more water than the line can supply. Or can they?

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    Quote Originally Posted by plisken View Post
    As for hooking hard suction to a Hydrant... It should only be used if it is tested for pressure.... Most suction is tested for vaccume..... But if you are a department without LDH/ Soft suction then you can use a section of hard suction..... It beats 2 1/2's or 3" ,, sometime better to use 6" but once again you must be close to a hydrant and it must be tested for pressure uses...... Hard suction is not used much for hydrants these days.....


    Sorry its called hard intake hose: rated for possitive pressure intake use..
    Actually for short runs the size of the hose doesn't make much difference. The friction loss over a 25 foot piece of hose is almost the same. Now obviously, a 1 inch hose won't flow what a 6 inch hose will. But a 3 inch hose will be pretty close to a 6 inch hose. In this case the venturi effect will take over and the water will actually accelerate through the smaller hose.

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    Quote Originally Posted by Geinandputitout View Post
    The only thing you are limited by is the number of discharges. A 1500 GPM pump rated at a draft can easily discharge more than that from a decent hydrant.
    We Have A Winner!!. You hit the nail on the head with that. We are still buying 1,000 GPM Pumps and hanging 6 or 7 2.5 discharges on them, because we have an excellent Hydrant System. At a recent training event, we were supplying 2 deck guns with 1&3/8th tips, 2 2inch handlines with 1&1/8th tips, and a 3 inch handline with a 500gpm combination nozzle. All from a 1,000 gpm pump.
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    Ok Trotter I wll explain this simple stupid...You lay in 500 ft from the only hydrant.... You are flowing 300 gpm ( 2 1.75" HL ) Now you look at your gauge and you still have 60 psi intake...(your not using) You can't go below 20 psi intake... that leaves 40 psi to spare. Now a second engine comes in and has to protect exposures,(hypo) they have 1000 gallons on board. You can run a 4" out of another INTAKE to the INTAKE of the second engine. You can supliment there tank with the other 40psi residual you have left over or they can flow 2 more handlines from what you are giving them.. They can be another 300' around the corner, behind the building what ever..... Your engine is not supplying them the hydrant is. The excess water never goes around your pump... You don't need the extra incomming water for what you are flowing.... Now you want to put a 2.5 in service.. The second engine is not going to get the water they need so they get the short end of the stick... but if you share the hydrant you can use this method...

    so 1000 gallons is comming from the hydrant, you are using 300 gallons, the rest is backing up un the hose and hydrant system.... Now if you send it to another rig (ding light goes on)


    As for the vaccum question... Compound gauge goes below 0.... This drops the bearometric pressure in the suction hose via the priming pump to create a vacuum in the hard suction hose..... this creates lift, of the water from below ( max lift 18 ' thero) to the pump... So yes a vacuum can be achieved...

    Now you are always going to get more water through a 6" than you ever will through a 3" I don't care how short the lenghts are.... Larger is more water less friction loss...
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    Quote Originally Posted by HotTrotter View Post
    But pumps don't pull a vacuum. This has been discussed at length here. They only can move what the forces of nature will supply to them.
    Never said that pumps pull a vacuum. I attempted to answer your question as to and I quote;
    Why would you use hard suction on a hydrant?
    By your little play on words, their should be not hard "suction" hose as water can not be sucked through the hose. I believe your question should have been;
    "Why would you use "hard intake hose" on a hydrant? (Thanks to plisken for providing the exact technical terminology ) The simple answer is cause almost everone had it and it was the biggest hose available.

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    Are you going to get more water out of a 12" hydrant at 80 psi or out a 4" hydrant main at 80 psi, when you are flowing 1200 gpm.... Venturi my butt... You can never achieve 1200 gpm through a 3" hose.......
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    Quote Originally Posted by Geinandputitout View Post
    The only thing you are limited by is the number of discharges. A 1500 GPM pump rated at a draft can easily discharge more than that from a decent hydrant.
    Actually, you are limited by the amount of water the hydrant can provide. If your hydrant is only capable of supplying 500 gpm there is no way to get 1000 gpm out of it. However, and I might be wrong, if you have a hydrant capable of supllying 2000 gpm a minute and it is going through a 1000 gpm pump, I believe the pump will actually exceed it's rated capacity.

    But the bottom line is, the pump will not be able to provide more gpm than what is available to it.

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    can we state the obvious any more. If you read the Quoted post he was talking about drafting... And yes you can exceed the rated pump capacity. No you cant draft from a hydrant,)on a system) Unless it is a dry hydrant, another reason to use a hard suction to a steamer connection...(dry hydrants are supplied by tanks under ground and by piping extending into a body of water) Yes you do draft from them but that is not the point of this thread. It is about dual or tandom pumping.... No hard sleeves needed for this tactic. Yes yu need a strong hydrant to do it but it works very well. spelled out enough for you!!!!!
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    Quote Originally Posted by plisken View Post
    Ok Trotter I wll explain this simple stupid...You lay in 500 ft from the only hydrant.... You are flowing 300 gpm ( 2 1.75" HL ) Now you look at your gauge and you still have 60 psi intake...(your not using) You can't go below 20 psi intake... that leaves 40 psi to spare. Now a second engine comes in and has to protect exposures,(hypo) they have 1000 gallons on board. You can run a 4" out of another INTAKE to the INTAKE of the second engine. You can supliment there tank with the other 40psi residual you have left over or they can flow 2 more handlines from what you are giving them.. They can be another 300' around the corner, behind the building what ever..... Your engine is not supplying them the hydrant is. The excess water never goes around your pump... You don't need the extra incomming water for what you are flowing.... Now you want to put a 2.5 in service.. The second engine is not going to get the water they need so they get the short end of the stick... but if you share the hydrant you can use this method...

    so 1000 gallons is comming from the hydrant, you are using 300 gallons, the rest is backing up un the hose and hydrant system.... Now if you send it to another rig (ding light goes on)


    As for the vaccum question... Compound gauge goes below 0.... This drops the bearometric pressure in the suction hose via the priming pump to create a vacuum in the hard suction hose..... this creates lift, of the water from below ( max lift 18 ' thero) to the pump... So yes a vacuum can be achieved...

    Now you are always going to get more water through a 6" than you ever will through a 3" I don't care how short the lenghts are.... Larger is more water less friction loss...
    You have lost me here. My first pumper in stops at the hydrant, and begins to lay in 1000 feet of ldh to the scene. Second pumper pulls up connects to hydrant and ldh then feeds first pumper. First pumper at the scene is using 300 GPM which probably mens to 1 1/2 inch lines. He has the capacity for 4 more. Plus you can run out of the ldh side to a gated Y and send even more. My truck at the scene can moves 1000 gpm. Pump at the hydrant can move 1500 gpm. I'm trying to understand why in gods name you would want to run another 1000 feet of ldh when all you have to do is send more up the existing ldh line?

    And how does drafting have anything to do with hooking to a hydrant??? I'm confused by that as well.

    You speak this time and then I will give you the last word, after all, that is what you are after.

    Max lift is actually more around 26 feet. It is determined by the approximately 14.7 psi of atmospheric pressure available. Now if I lose 5 psi (close enough for the fireground) per 10 feet of lift, how far can I go?

    Oh yea, one other thing, all of our hyrdants only have 2 2 1/2 inch connections. What is the maximum amount of water I can get though a 2 1/2 opening? (trick question)

    so 1000 gallons is comming from the hydrant, you are using 300 gallons, the rest is backing up un the hose and hydrant system.... Now if you send it to another rig (ding light goes on)
    I've read this four times and laugh every freaking time. If you are only using 300 gpm then you don't need anymore water at the scene. And that is the light that goes on
    Last edited by HotTrotter; 05-09-2007 at 08:27 AM.

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    plisken, I understand doing this intake/intake setup if the engines are right next to each other. Not sure I'd do it when the engines are 300' apart. Seems easier/better to me to put the 5" on discharge at the point. Makes up for the minor friction loss as well.
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    I believe it got it's origin back hne pumpers couldn't pump as much. With newer equipment we can pump a lot more than the old equipment. I would say this is a method that is definitiely outdated. How about we take a poll. How many departments would actually use it?

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    More likely it was due to the limited number of discharges, not pump capacity. Do I think my department would utilize this particular pumping evolution during a fire? No, not likely.

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    Quote Originally Posted by kayakking View Post
    For what I've learned as "dual pumping", their is no need for hard suction hose.
    The scheme we had was to close the hydrant partially so you could hook up the second engine to the other suction port on the first engine without having them stop pumping. To do that you can't use a soft suction (or so they tell me). Got me, like I said, not only has it not been used in recent memory, it's not even been drilled. There just aren't too many places in the district now where you just wouldn't run more line from a different hydrant.

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