Dual Pumping Operations -outdated?

[Catch22]

We don't have these "hydrant" things you speak of around here. We have to go out of town to play with those. So I have to ask the million dollar question here.

WHY?

Wouldn't it be more effective to just run two supply lines off the hydrant, one for each truck?

One situation I've seen we should have used it where I work is a defensive fire on a three-story (and basement) balloon frame structure. Hydrants on both ends of the block, but one would require cutting off a major highway. The other hydrant available was on the other back side of the structure and was being used by another engine. Engine layed into the truck, which was pumping four attack lines. We subsequently starting pumping the stick (which is always taught as a no-no to pump attack lines and stick).

What we could/should have done was dual-pumped that hydrant (8" main, plenty of water and pressure) and let the truck pump the stick and the engine pump the attack lines or another master stream. The alternative would have been to lay dual 3's off that hydrant (after shutting it completely down) to one or the other for about 250'. Dual pumping would have let us maintain the flow from the truck and hooked up the engine to it.

[decou151]

In Jersey, dual pumping is referred to as tandem pumping. It was used much more prior to LDH but we still train on it.

[Catch22]

In Jersey, dual pumping is referred to as tandem pumping. It was used much more prior to LDH but we still train on it.

That's kind of funny as it brings back a recent debate I was involved with. When we were writing the portion of our driver's academy with all of the relay, tandem, and dual pumping information, we got into a bit of a heated discussion. Several of us had different ideas on what each one was. When we got out the IFSTA manual, we found out we were all wrong in some manner.

Not saying NJ can't do it their own way, but what we learned (IFSTA-wise, at least) was relay is pumping water long distances using mulitple engines to boost the pressure. Dual was hooking intake-to-intake to maximize the water from a single source. Tandem is one truck pumping into another to boost pressure, basically creating a two-stage pump out of two single stage pumps.

Given the right circumstances, there's a use for any of the three techniques (no matter what you want to call them).

[hwoods]

We don't have these "hydrant" things you speak of around here. We have to go out of town to play with those. So I have to ask the million dollar question here.

WHY?

Wouldn't it be more effective to just run two supply lines off the hydrant, one for each truck?

Short Answer - No.

Longer Answer - Although we don't remotely claim to have invented Tandem Pumping here, we have used it since the 1920's. Our operation starts with the first Engine pulling up to a good Hydrant, and connecting their SOFT Suction Sleeve to the Steamer outlet on the Hydrant. They hook up, turn the water on, and charge the lines laid down the street to the Fire by other Engines. When the First Engine runs out of Discharges, but still has a good residual pressure, a second engine is placed in position to attach their sleeve to the large intake on the First Engine. When everyone is ready, a FF slowly starts shutting down the hydrant. When the residual approaches zero, the Cap is taken off the first Engine's intake and the second Engine's sleeve is attached. Then the Hydrant is opened up full again. The second Engine can then attach and charge additional supply lines to Engines on the Fireground.

Coupla points - We have a lot of Hydrants that would be unheard of in many communities. One that we use for training has at least a 3,000 gpm flow. Our Hydrants are all R.D.Wood Mfg. "Standard" models, with one 4.5 and 2 2.5 discharges. And, we ALWAYS put an Engine on the Hydrant. ALWAYS.

[nmfire]

Engine 1 stops in front of house on fire, catches their own plug, and pulls off 2 preconnects to attack the fire.

Engine 2 pulls up...they did NOT catch a plug, they pull a couple of their own preconnects off but do NOT have an easily accessible plug. Engine 1 isn't using all the water that is available from their hydrant.

Engine 2 can hook a short sleeve of 5" (not hard suction) from their intake to Engine 1's unused intake. The reason it has to be on the intake and not the discharge of E-1 is simple...Engine 2 does not want any additional pressure from Engine 1...(remember, E-1 is pumping attack lines, we don't want 150 psi pushing water to E-2 through 15' of 5" hose) If we attached to E-1's discharge we would get all the pump pressure (unless we gated down)...but why gate down since you can attach to the intake and avoid the risk of water hammer altogether.

Perfect explanation. Makes sense to me now. Sounds like something to try the next time we have a good water supply setup at a drill.

[Dalmatian190]

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.

[plisken]

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.

[FlyingRon]

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.

[kayakking]

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.

[kayakking]

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.

[plisken]

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??

[HotTrotter]

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.

[Geinandputitout]

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.

[jlcooke3]

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.

[plisken]

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.

[plisken]

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..

[HotTrotter]

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.

[HotTrotter]

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?

[HotTrotter]

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.

[hwoods]

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.