Dual Pumping Operations -outdated?

[plisken]

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...

[jlcooke3]

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.

[plisken]

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.......

[HotTrotter]

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.

[plisken]

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!!!!!

[HotTrotter]

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

[Bones42]

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.

[HotTrotter]

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?

[jlcooke3]

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.

[FlyingRon]

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.

[RFDACM02]

So just laying out an LDH and gating it back isn't a lot easier,faster and more efficient? It would seem to me that marrying to engines together in tandem pumping evolution could spell trouble if the first engine has a pump issue. But if you use to ports of the hydrant to inividually supply the two engines won't they be fighting for residual pressure? If they don't communicate and one opens their deck gun when the other has less residual wouldn't that cause the other to go to 0 psi quicker?

Of course I fully support teaching tandem pumping because it goes in the "more you know" category. We as a fire service are letting things go left and right. Someday someone will realize that there may be a need to pump in tandem for what ever reason and most people won't have a clue!

[HotTrotter]

So just laying out an LDH and gating it back isn't a lot easier,faster and more efficient? It would seem to me that marrying to engines together in tandem pumping evolution could spell trouble if the first engine has a pump issue. But if you use to ports of the hydrant to inividually supply the two engines won't they be fighting for residual pressure? If they don't communicate and one opens their deck gun when the other has less residual wouldn't that cause the other to go to 0 psi quicker?

Of course I fully support teaching tandem pumping because it goes in the "more you know" category. We as a fire service are letting things go left and right. Someday someone will realize that there may be a need to pump in tandem for what ever reason and most people won't have a clue!

That is one way to look at it. The other way is the more useless knowledge I get the higher the likelyhood I will forget something really important.

And really, how many hydrants have 2 steamer ports on them? Todays trucks can easily handle that capacity. It is a tehnique that had a place when trucks had smaller pumps. It would be crazy in todays environment to buy a truck with a less than 1250 gpm pump. The better method is to use individual feed water mains to feed different hydrants each feeding a different pumper. It is really senseless to put two aparatus at the same hydrant pumping from the same hydrant, unless your trucks only have 300 gpm pumps.

[RFDACM02]

That is one way to look at it. The other way is the more useless knowledge I get the higher the likelyhood I will forget something really important.

Come on, you don't really expect that we'll beleive you only have some much room in your brain? If you learn something you have to forget something else? I realize tandem pumping might be a stretch for most of us, but nowadays so many firefighters only know how to throttle up until the needle is pointing at the tape! So little understanding of why you can't draft over 22 ft. or that all pressures are equal in a closed system! I don't beleive it can hurt to teach and practice these evolutions as long as you can keep up with the rest which may be the real challenge.

And really, how many hydrants have 2 steamer ports on them? Todays trucks can easily handle that capacity. It is a tehnique that had a place when trucks had smaller pumps. It would be crazy in todays environment to buy a truck with a less than 1250 gpm pump. The better method is to use individual feed water mains to feed different hydrants each feeding a different pumper. It is really senseless to put two aparatus at the same hydrant pumping from the same hydrant, unless your trucks only have 300 gpm pumps.

I think HWOODS describes the perfect scenario of why some depts wouldn't waste money on a pump over 1000 gpm. I'd agree individual mains or grids are a better choice, but it depends on hydrant spacing and flow. We have a few places where tandem pumping would be a benefit, though I'd probably opt to just stretch a 5" LDH from the original engine. You do understand that the GPM rating of your pump is meaningless on a big hydrant if you have adequate discharges right? You can use a 1000 gpm pump as a 2500 gpm water manifold. We've flowed around 3000 gpm using a 1500 gpm pump off one of better hyrdants.

Again, not a high priority in most places but a valid technique that may be of value at some point. I still am not sure why supplying the 5" LDH is not a better option? It seems easier and faster.

[Rescue101]

You guys still don't get it. 1 hydrant,two 5(or 6")soft sleeves and marry the intakes of the two pumps together.If pump one fails,the water will still flow to pump two.Both pumps will operate to the capacity of their ratings or the Hydrant whichever occurs first.Needless information? I'd guess that would depend on your hydrant and street layout. I'd add it to my useful to know,not essential file.I think we've used it maybe five times over 38 years I've been here.I regard it as more of a pump operator familiarization/confidence tool than a daily driver.But certainly an important skill that can still have a place in this world. T.C.

[hwoods]

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.

We did this, from time to time, both in Training and on Fires, as long as I've been around. We do it with Soft Suction Sleeves with no problems. A number of other posters have mentioned LDH, but out of 90 Engines, only about 6 carry LDH. For whatever reasons, folks in this area do not want to use it, preferring 3 inch Suppy line.

One Station, the Clinton VFD, ( www.clintonvfd.org ) Runs County-wide as the Water Supply Company on Second Alarms. Their Apparatus carries a large amount of LDH, and 2,000 or 2,250 GPM Pumps. They also took a "Utility Body" 4X4 Pickup and set it up with 1,200 feet of 5 inch Hose. This unit can stretch supply lines in to units already working in congested areas much easier than full size Engines.

[kayakking]

You guys still don't get it. 1 hydrant,two 5(or 6")soft sleeves and marry the intakes of the two pumps together.If pump one fails,the water will still flow to pump two.Both pumps will operate to the capacity of their ratings or the Hydrant whichever occurs first.Needless information? I'd guess that would depend on your hydrant and street layout. I'd add it to my useful to know,not essential file.I think we've used it maybe five times over 38 years I've been here.I regard it as more of a pump operator familiarization/confidence tool than a daily driver.But certainly an important skill that can still have a place in this world. T.C.

Thank you...at least I know there is another person out there who is actually talking about dual pumping and not something else. It's kind of entertaining to read an argument about the merrits of an evolution when we haven't all even reached a point of agreement on what the evolution is.

[hwoods]

Thank you...at least I know there is another person out there who is actually talking about dual pumping and not something else. It's kind of entertaining to read an argument about the merrits of an evolution when we haven't all even reached a point of agreement on what the evolution is.

I think that there are only 3 of us......

[Catch22]

Needless information? I'd guess that would depend on your hydrant and street layout. I'd add it to my useful to know,not essential file.I think we've used it maybe five times over 38 years I've been here.I regard it as more of a pump operator familiarization/confidence tool than a daily driver.But certainly an important skill that can still have a place in this world. T.C.

While I tend to agree with what you're saying in regards to the need to know, I do think it's an underused operation. I've been one several scenes in hydranted and rural areas where the practice would have been beneficial. However, like you said, it depends on the department and water supply.

We haven't got to try it yet (in a drill, we don't want to do it in a real-life scenerio for the first time), but we've discussed at length of using it while relaying water to a scene. If we place our 1,750 pumper/tanker at a water source close to a fire and can push the 1,750 (or even 1,500 or so) to the scene, we can supply our primary unit flowing it's master stream at 1,000 gpm. We can then hook on ours, or another department's, apparatus in a dual-pumping situation and flow another 500 or so worth of large hoselines or master stream.

I mentioned a page or two back a scenerio at my career department where it would have been handy to use instead of pumping my stick and four attack lines off of my quint. We could have dual pumped another stick or the hoselines/master stream off an engine off the same hydrant that had plenty of water left even with me pushing upwards of my 1,500 gpm capacity.

[RFDACM02]

So as one of the people that must be "missing something" here? How much water will flow through the first pump if there is a failure and it won't turn? I'm really asking here. There is some mechanical restiction from one side to the other of the pump. Will you only lose one pump? Or will you even temporarily draw a vacuum? Like I said, I think there is value in knowing the evolution, but it seems less practical where LDH lays in the streets. Maybe (probably) many engiens are not capable of discharging more than their capacity?

[Catch22]

So as one of the people that must be "missing something" here? How much water will flow through the first pump if there is a failure and it won't turn? I'm really asking here. There is some mechanical restiction from one side to the other of the pump. Will you only lose one pump? Or will you even temporarily draw a vacuum? Like I said, I think there is value in knowing the evolution, but it seems less practical where LDH lays in the streets. Maybe (probably) many engiens are not capable of discharging more than their capacity?

I'm not sure that running water through a non-operating pump is exactly "dual pumping," but I'll try to answer your question (I'm sure someone will correct me if I botch it). The intake manifold has no obstructions within it (other than valves). So, you can supply a helluva lot of water straight through one suction port to the other with only a little friction loss.

I have had to pump "through" a pump before. Our situation was that we had some icing issues with our first arriving engine. We had already pulled attack lines and were working to resolve the issues when the second due engine arrived. Instead of wasting time trying to get the pump working, we hooked the hydrant to the second arriving engine, hooked in from the discharge on the operating pump to the discharge on the broken pump, and pressurized the discharge side of the malfunctioning pump. Of course, the pressure carries through to the intake side through the impellor, but it's not an issue. One could also hook into the intake side of the malfuctioned pump, but you'll have some friction loss to deal with through the impellor, but I've seen it done several times.

Dual pumping is when you supply engine 1 with water from the source. You then connect engine 2 to the intake side of engine 1 with hard/soft suction. Both engines get water from the same source. It saves issues with pumping water from engine 1 (through a discharge) to engine 2. "Textbook" says you're not supposed to pump LDH (or master streams) and attack lines from the same pump. Imagine what happens to the guys on the end of a hose if you shut down a discharge flowing 750-1000gpm too fast.

Is that close guys?