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Thread: 2000 GPM Pump overkill ?
06-24-2002, 08:11 PM #1
2000 GPM Pump overkill ?
Last edited by Fire304; 06-24-2002 at 08:17 PM.
06-24-2002, 08:33 PM #2
My FD recently bought 2 new trucks, both with 2000 GPM Q-Max pumps, one is a CAFS system. We have a great hydrant system in most of the town, and almost never draft, but there were two key reasons for going big water. #1, our tower is piped to flow 1500GPM so if we want to self feed from the tower's pump, or if we want to run CAFS from the engine through the pipe both pumps needed the capacity to more than supply the pipe and maybe some handlines. #2, a 1500GPM Q-max and a 2000GPM Q-max are the same pump, and cost us the same money to install, and we had the HP on our engines to run it, so we said, what the heck, why not.
Dalmation90 has an excellent point that you can always flow less water, when you need more it really hurts to not have the capacity.
That said, in all reality, I believe you cannot flow 2000GPM through one piece of 6" suction. When our trucks were pump-tested they were set up to draft from both sides. We also had our pumper set up with a 4" pipe discharge to feed our 5"LDH. Since this is a CAFS pumper we can move amazing amounts of water through the LDH if it's sent out as CAFS (no friction loss, no water hammer). If we're willing to take a slight loss in plumbing and hook LDH to a 2 1/2 discharge we can actually feed two master streams or a stick and an attack pumper via two LDH lays.
As for when you would flow 1500+GPM, you're right Bob, almost never except in big defensive ops. That would be 10 1 3/4 inch lines, or a half dozen 2 1/2'ers. If you can't put most fires out with a 750 GPM pump then call for help 'cause you in big trouble. But if you have any industrial facilities in your town, then the day may come when 1500 GPM is not enough.
06-27-2002, 11:43 PM #3
- Join Date
- Aug 2001
Is bigger better? Well, first we have to look at the rural vs. suburban/urban as two very different scenarios. In the rural case where the pump is drafting from a static source - I would say that this pump is developing the entire water supply - all of the volume and all of the pressure. In this case, 2000 gpm or maybe more seems reasonable. I wouldn't characterize a 2000 gpm pumper in this application as overkill.
However, when we move to the typical suburban/urban environment with a fully hydranted municipal supply, now I think the 2000's start to get into the unnecessary/useless range. In this case, the pumper is a booster pump - the flow is entirely dependent on the water system, the engine can boost the pressure, but volume is already determined and there is already some amount of existing pressure. And from what I see, there are plenty of depts with full hydrants going the 2000 gpm route. I think it boils down to three issues: one, there just isn't that much volume to supply a single pumper of this size, two, even if you have the supply, a lot of depts can't get that supply to pump (supply line issues), and three, even if a dept has the supply and can get it to the pump, on the whole, typical pumper discharge configurations and fire service strategy and tactics just can't make good use of that much water.
1. Municipal supplies are too small for a 2000 gpm - my day job is filled with fire sprinkler/standpipe systems and fixed fire pumps. I've done a lot of water flow testing and looked at supplies from all over the US and I just don't see the supplies to support a 2000 gpm pump. My work is in commerical/industrial areas with bigger mains, etc. and the more typical useable supply is in the 1200 - 1700 gpm range. I rarely see a supply beyond 2000 gpm. And residential would only be less. I am working with an industrial plant with 2000 gpm pumps with 12" suction piping off 16" municipal mains and all we can get is about 2400 gpm. Per NFPA 20, I should be able to flow to 150% or 3000 gpm. Technically these pumps are oversized. That's 2400 gpm max with 12" suction piping off 16" mains. That 2000 gpm pumper isn't even going to do 2400 gpm since I doubt the supply hose configuration would be the equivalent of a direct 12" connection to that 16" main. You might be aware of ESFR sprinkler protection for warehouses - its popular today.The demand for an ESFR system ranges between about 1000 gpm to 2000 gpm - and there are problems all over with water supplies that can't meet the demands of these systems, pumps are having to installed with low suction pressure cut-offs so that the pump doesn't suck the mains dry if you get even more heads open up than designed for.
So if you figure a decent water system can supply 1500 gpm, I took a typcial water supply and added a 1000 gpm pump to it - guess what, that's the equivalent of a 1500 gpm pump from draft. Hale also advertises the 1000 gpm to exceed 1500 gpm from a pressurized source. Add a 1250 and you're equivalent to a 2000 gpm pump and add a 1500 gpm and you can be in the 2500 gpm range if the volume is there. So when I look at a 1000, 1250 and 1500 gpm pump, you can essentially max out on most any water system in the US. From the water supply data I've seen, a 1000 or 1250 would be fine and if you really want to make sure you can use every drop, spec the 1500.
But the 2000, it's simply a waste in many cases. And there is HP issue. You can run a 1000/1250 off a mid-range diesel, stick with an MD transmission,etc. You get to 2000 + and you've got to go to a premium, high-end diesel with a HD - that's real money. And when we still don't have the thermal imagers we need, or radios, etc. I can't see wasting it on HP and pumps we can't use. And otherwise if we have everythign we need, how about leaving the $$ in the tax payers pockets, the people who earned that money.
So a dept might have the volume, let's look at supply lines - NFPA 20 is the standard for fixed fire pumps - they establish minimum suction pipe sizes: 8" for 1000,1250,1500, 10" for 2000 gpm. These might be a bit conservative, but this is line size you need to be able to supply such a pump size (if the supply exists) without running into cavitation problems. How does that compare to how we supply our pumpers. Someone else mentioned it - compare our supply lines to the suctions used when these bigger pumps are pump tested? Again, on the whole, I don't think the fire service can supply these bigger pumps, even if the supply existed. You've got to make a big leap in thinking to supply these bigger pumps and I know many a dept still laying dual 3's or a single 3 when they THINK it's only a small fire. I read in this forum often about how this dept or that wants to stick with 4" becuase they think 5" is too heavy to re-load or because it's difficult to move once it gets charged. You want to move 2000 gpm + you need to be ready to lay some above-ground water mains (and you're not gong to move them) and then pick it all up. Again, things just don't jive - you read on the forum that bigger is better when it comes to pumps and then you read we want small supply lines becuase the other stuff is "too heavy." Can't have it both ways.
And finally, even if you have the supply and can get it to the pump intact, the fire service just isn't that good at attacking fires, whether you're talking an offensive or defensive type strategies/tactics, that require multiple 1000's of gpms for control/extinguishment. Not that it can't and isn't done, but again, on the whole, I don't think we are that good at it. The first thing we have to do is put an elevated master stream on most every pumper moving 1000-1250 gpm and two leave all the handlines on the truck. And you can't do this lobbing a smooth bore in off a deck gun. And you can't manually effectively knock down fires that require multiple 1000's of gpm- all you really need is 2 guys per truck - someone at the pump and someone on the master stream or as a spotter. But this is just foreign to most depts - this isn't manual firefighting, its basically using large equipment - you're almost an equipment operator, not a firefighter and again, this is a huge jump for the fire service. What's everyone else going to do??
So if a dept can put together all three - a water supply, supply lines, and an effective way to deliver multiple gpms in 1000 gpm + streams to the seat of these big fires - I think a 2000 gpm pump would make a lot of sense.
But for the average FD out there, I think a 1000 or 1250 would do just fine for them, 1500 if you want to be really sure you don't leave any extra in those mains!
06-28-2002, 08:17 AM #4
- Join Date
- Aug 2001
I ran some quick calculations after the last post. If a dept says that they need to go to 2000 gpm pumps for the hydranted district because a 1500 can't flow the full capacity of the water system - if they aren't laying dual 6", they just won't move that extra water beyond the capacity of a 1500. The fire service is still full of dual 3's, 4, and 5.
You want to move big water and you're talking laying dual LDH - dual 5's to max out those 1500's and dual 6's if you want flow the 2000 to capacity. Some of us are still complaining about a single 5. I don't think the fire service is quite ready to start laying dual LDH on the whole - until then, leave the big pumps to the industrial pumpers, they know and are ready to lay what is needed.
06-28-2002, 10:01 AM #5
Numbers using Angus Hi-Vol for 5"
150psi PDP (maximum volume from draft)
20psi incoming pressure @ scene
To push 1500gpm 3000', you'll need a relay pumper around the 1500' mark.
20 psi Incoming on scene
180psi PDP (gives you about 1500gpm discharge)
20 psi Incoming on scene
By moving to a 2000gpm source pumper and taking advantage of Supply LDH's working pressure of 180psi, that 2000gpm pump can push 1500gpm 400' further than a 1500gpm pump.
1 -- 1500gpm pump can deliver 1400gpm @ 2000'.
1 -- 2000gpm pump can deliver 1500gpm @ 2000'.
2 -- 1500gpm pumpers in relay can deliver 1500gpm @ 2000'.
2 -- 2000gpm pumpers in relay can deliver 2000gpm @ 2000'.
2 -- 1500gpm pumpers in relay can deliver 1400gpm @ 4000'
2 -- 2000gpm pumpers in relay can deliver 1500gpm @ 4000'
So depending on your situation, 2000gpm pumps could be as little as a 100gpm difference or 500gpm difference in water delivered to the scene using a single 5" line.
I'd agree with CILFD you need to look at dual 5" or single 6" to really take advantage of the 2000/2500/3000gpm pumpers in most situations.
Systems like Angus' Fetch (http://www.fireweld.com.sg/FIRE/Fire.../Duraline7.htm) (and there's a Texas company that makes a competeting system whose name I can't remember) scream for this kind of application -- use a rear mount pump, a good sized hose bed, able to be split-loaded so you can either lay duals or a long single!
06-29-2002, 12:49 PM #6
- Join Date
- Nov 1999
So can our three Engine Co.'s carrying 600' of 6" and 800' of 5" with hydrant spacing every 300' to 400', supply our Tower which can flow 4500 GPM from 2 monitors in the platform and 2 deck guns? Allthough, our new pumper being speced now for a 4000GPM pump should help that problem.Stay low and move it in.
06-29-2002, 01:06 PM #7
- Join Date
- Aug 2001
Can you share some of your hydrant flow testing data? Can you put up some representative hydrant data - some statics and residuals flowing x gpm? I assume you are taking suction directly from hydrants. And have you flow tested your water supply at higher flows and not simply extrapolated from low flow data?
Sounds like you can discharge it and will be able to pump it. I'd be interested in the entire hydraulic analysis - water supply to supply lines, to pumps, to discharge. Like to see a dept that actually has the analysis and testing from water suppy to discharge.
Can you lay out an entire scenario- give us a hydrant (or two) that you would use with flow characteristics, what supply lines, to what pumps (what is the intake arrangement), and how would you discharge.
06-29-2002, 01:35 PM #8
- Join Date
- Nov 1999
We just recently completed our latest ISO evaluation and the data should be readily available in one our "super books" prepared for them. As you know, hydrant flow tests and the like is looked at by ISO during a grading. I'll get back with you when I have it and post it.Stay low and move it in.
07-02-2002, 11:32 PM #9
- Join Date
- Jan 2001
Please answer the following questions for both the FDNY and the Dravosburg, Pa Fire Department (perhaps Archer131 and anybody familiar with the FDNY's tactics could give you some help if you need it):
-Number of engines on first alarm
-Average engine company staffing
-Total staffing on first alarm
-Total number of engines (department wide)
-Total on duty staffing (department wide, per shift)
-Method of water delivery for 99% of structures (describe scenario)
By the way, Boston's engines have all been 1,250 gpm for years. Is Pierce better than E-One? I guess they haven't had time to find out.
I think Dalmatian and others pretty much hit the nail on the head in this and the rear-mount pumps thread, so I won't bother repeating it.
STATION2: Just curious, who is building the pump for your new rig? Is the 4,000gpm the 8FG when working off of a pressurized water source?
07-06-2002, 01:35 PM #10
- Join Date
- Aug 2001
For anyone interested in the real performance difference between a 1250 gpm and 2000 gpm pump in a hydranted district, read on. Summarized below is the performance difference between a Waterous CS series 1250 gpm pump and a Waterous CSU series 2000 gpm. These are both in Pierce engines. Actual pump performance curves for both pumps were used. Supply line(s) are 200' in a forward lay directly off a hydrant. Hazen-Williams of 150 was used for the supply lines in the calculations. Discharge performance (flow/pressure) is directly at the pump discharge, no discharge piping, etc. Minimum discharge pressure of 150 psi/minimum hydrant residual of 10 psi.
Water System #1 - 50 psi static/2000 gpm @ 40 psi (Industrial area of large mid-western city)
1250 GPM pump
1- 5" supply line: 1920 gpm @ 213 psi w/ 40 psi residual @ hydrant (approx. 250 HP required)
2- 5": 2970 gpm @ 161 psi w/ 29 psi residual @ hydrant (320 HP)
1- 6": 2730 gpm @ 174 psi w/ 32 psi residual @ hydrant (318 HP)
2- 6": 3050 gpm @ 157 psi w/ 28 psi residual @ hydrant (330 HP)
2000 GPM pump
1- 5" supply line: 1960 gpm @ 222 psi w/ 40 psi residual @ hydrant (approx. 290 HP required)
2- 5": 2970 gpm @ 171 psi w/ 29 psi residual @ hydrant (345 HP)
1- 6": 2740 gpm @ 184 psi w/ 32 psi residual @ hydrant (342 HP)
2- 6": 3290 gpm @ 155 psi w/ 24 psi residual @ hydrant (350 HP)
Just to see how much could be had from that water system, I ran triple 5", triple 6", and 4 - 6" supply lines to the 2000 gpm pump:
3- 5": 3251 gpm @ 157 psi w/ 25 psi residual (355 HP)
3- 6": 3386 gpm @ 151 psi w/ 24 psi residual (352 HP)
4- 6": 3410 gpm @ 150 psi w/ 23 psi residual (360 HP)
For those that are interested in flow, you can see that unless you lay dual 6" to the 2000 gpm, the 1250 gpm keeps right up. What you actually gain from the 2000 gpm is a small increase in pressure at the same flow. As I mentioned in my earlier post, when taking suction from a municipal water supply, your engine is a booster pump, the flow is governed by the water system. And what the 2000 gpm buys you is a small increase in pressure at the same flow. The pumps both flow the same, but if you know what a centrifugal pump curve looks like, the 2000 gpm can deliver the flow less far out on its curve, producing a little more pressure.
Something to mention about these max flows and pressures - these are right off the pump discharge. Any piping, hose, etc. that creates the first psi of friction loss will begin to reduce the flow from the pump. So, if you do lay the 6" duals to the 2000 gpm, you have to be able to discharge that extra 300 gpm, you need to discharge all 3300 gpm without essentially any friction loss. This pretty tough to do, so in reality, from a flow standpoint, on this pretty strong hydrant, it would very difficult for the 2000 gpm to outflow the 1250. What the 2000 buys you is 10 psi of discharge pressure.
So, in my opinion, a 1250 with maximized intakes (dual 5's or a single 6") and efficient discharges will beat a 2000 everytime.
As you can see, the limiting factor on this high gpm hydrant is supply line size. A single 5" is going to choke a 1250 or a 2000 to essentially the same performance.
Now using a a more typical hydrant: Static of 50 psi/1500 gpm @ 20 psi (older section of NE large city)
1250 GPM pump
1- 5" supply line: 1380 gpm @ 240 psi w/ 24 psi residual @ hydrant (approx. 230 HP required)
2- 5": 1700 gpm @ 225 psi w/ 12 psi residual @ hydrant (297 HP)
1- 6": 1635 gpm @ 228 psi w/ 15 psi residual @ hydrant (292 HP)
2- 6": 1760 gpm @ 221 psi w/ 10 psi residual @ hydrant (308 HP)
2000 GPM pump
1- 5" supply line: 1340 gpm @ 249 psi w/ 25 psi residual @ hydrant (approx. 252 HP required)
2- 5": 1670 gpm @ 236 psi w/ 13 psi residual @ hydrant (306 HP)
1- 6": 1661 gpm @ 236 psi w/ 32 psi residual @ hydrant (304 HP)
2- 6": 1738 gpm @ 233 psi w/ 10 psi residual @ hydrant (323 HP)
In this case, no matter what the supply configuration, the 1250 and 2000 produce very similar performance. If you are looking for pure gpms, the 1250 actually outflows the 2000 by a small margin, again with 10 psi less pressure. And even with this lower flow hydrant, the 5" is choking both pumps. 5" is going to give you 1400 gpm or so and that's it. You've got to go to dual 5's or a 6 to max out this water supply.
As I said earlier, if a dept has the water supply, the supply lines, and discharge to go to those 2000 + gpm pumps - great. But who is laying dual 6's? and who can discharge 3000 + gpm off a single pumper and do so with very little friction loss?
Someone can take a 300-350 Hp commercial rig with a 1250, lay dual 5's, maybe some type of elevated master stream, etc. and if it is properly piped, etc. and for probably less than 1/2 the cost can considerably out perform one of those custom war wagons with 500 hp, 2000 gpm pumps. All show, no go.
I guess if you want to spend the taxpayers money on expensive trucks that won't perform, that's part of how the fire service buys it's equipment. As a taxpayer as well as a firefighter, that doesn't help the fire service gain credibility with the public. I'll fund appropriate equipment, but no more. Someone mentioned buy up so that you have it when you need it - sure, if you truly can use that capacity. If you can't, then you really are just wasting money and beyond the most liimiting factor, what you've got is pretty much a toy.
07-19-2002, 02:33 AM #11
- Join Date
- Feb 2001
- Dravosburg, Pa
I have to agree with cifd. We just had a similar discussion tonight in a truck committee meeting. With all the numbers said and done you have to remember unless you have the supply either residential or comercial you can take all the numbers you want and throw them out.
As a side note I have heard it from two dealers now that the price between a 1250, 1500, 2000 are the same. So maybe that takes in account why so many are switching to a 2000 GPM pump on a new apparatus.
I will be starting a new thread on single -vs- 2 stage pumps!Living today to Protect Tommorow!
07-20-2002, 01:03 AM #12
- Join Date
- Aug 2001
- Syracuse, NY
water in, water out . . .
Can't go along with the group on this one. Syracuse has used all 2000gpm engines (Hale single-stage) since 1975, and will continue to do so. Our engines are equipped with four 1-3/4" crosslays (soon to go to two 1-3/4 and two 2"), and a 50' Tele-Squrt with a 1000gpm TFT nozzle. We are blessed with an abundant water supply system - over 7000 hydrants, none less than 80 lbs. Our typical supply line is twin 4" lines. WE have "done the math" over and over, flow testing and also using the old Mark I Eyeball (don't be held captive by your figures. They rarely tell the whole story). We have found that the very small additional expense for a 2000gpm pump is more than outweighed by the convenience of having it. It only has to be better than a 1250 or 1500 ONCE to be worth it, and in the 30 years I have been on, they have been used at capacity or close very few times, but brother, they were there when we needed them.
I fully agree that not every department can supply a 2000gpm pump, or use all that water effectively if they could get it. But we can, and do. Now, does that mean we would buy a 3000gpm pump if we could? No. As I said, we have done the math, and made the switch to 1500gpm in 1969 and 2000gpm in 1975 . . . because we can supply it, and apply it.
As is so frequently the case, to state that someone should ALWAYS or NEVER use something is an exercise in futility. You will usually be proved wrong (notice I didn't say "always"?).
Captain Dave Reeves
Syracuse fire Department
"An ISO Class 1 Fire Department" . . the only one in NY State!
07-20-2002, 01:47 AM #13
- Join Date
- Apr 2002
- Happy Valley, South Australia
Very interesting line of discussion. Here in Australia we are limited in the size pumps that we use due to the size of our water mains.The average hydrant is 150-200 mm and gravity feed so we find that most of our pumpers have cavatation problems useing a supply line of 64mm or 2.5". We have 2 pumpers 1 has a Darley 350 gpm midmount and the other has a Darley 500 gpm rear mount pump. We are a volly service who are one organisation that bulk purchases appliances. This can have some downfalls when you don't have much input into what you get.One of the newest appliances to go into service has 750 gpm pump on it and the find that a tanker is often needed to keep up supply or simply don't use the full capacity. One other problem is relay pumping to the paid fire service. This has become an issue because they have recently replaced most of their fleet and they have specced 1000 gpm pumps that we simply can't supply without being sucked dry.
I guess we need to strike a happy medium between supply and demand and my personal belief is that 750 gpm would be good because we can supply a better rate to the paid guys but can also back off with our own supply and call a tanker to assist if need be. Large pumps here are only useful in large industrial areas.These are my personal views and not those of my service.
07-22-2002, 01:55 PM #14
Archer131, you're right about pump prices, our two new trucks both have 2000gpm Q-max's for the same price as a 1500. If we had spec'd a 1500 then would have put a blank-off plate over two of the 2 1/2 inch ports on the pump (in other words, its the same pump).
Fyreline, We too are blessed with big hydrants. Typically we use a single 5" lay but all our trucks carry the stuff and we have done multi lays where required. I have seen the new tower flow 1500gpm and still have enough residual to use a handline or two.
dunj, what is your fire loading like? I ask because when I visited Bermuda a few years ago I saw their primary attack truck was not much larger than what we'd call a brush truck up here. I got into a very interesting conversation with the crew and they told me most of the homes on the island are stone and motar construction versus wood here in the US so fire loads are tiny since most of the house cannot burn. Also, all the homes had a water cystern (sp?) in the basement which could be used to supply the fire trucks. The LT. told me that they had not had a house destroyed by fire in years, and that one was arson anyway. Mostly room content fires. Most of us in the US shifted away from multiple 2 1/2 supply lines in the 80's in favor of much larger flow and easier laying single large diameter hose (ldh) of 4" or 5" (13cm). These hoses alow us to flow 1000 and 1500 gpm respectively.
Last edited by Fire304; 07-22-2002 at 02:27 PM.
07-23-2002, 03:21 AM #15
Coming soon to a department near you.
Although I've seen higher capacity (2000 gpm+) pumps in industrial departments for several years now, there are now 2250 gpm pumps turning up on apparatus delivered to municipal departments. Can the 3000 gpm pumps be far behind?
07-23-2002, 06:37 PM #16
- Join Date
- Jan 1999
- Marmora NJ. USA
I think the statement that going from 1500 to 2000 and not costing much is a little misleading. If you already have a high horsepower engine in your apparartus the increase in gpm will not cost much. But if you do not have a high horse power engine in your apparatus to drive a 2000 gpm pump. The cost to get the horse power to drive the pump is costly. Larger engine, larger transmission, larger pump transmission and also may need larger axles and brakes to handle the extra weight. And some chassis will not hand larger engines.
07-23-2002, 06:55 PM #17
DC14398, you're right about HP, we had a 73,000 lbs tower truck which needed a 500HP engine and a 53,000lbs pumper with a 470HP so we had plenty of horse power. If we had a lighter truck with only a 350HP then we could not have gotten the 2000GPM pump w/o a bigger engine. (I think 350 would have yielded a 1500GPM pump).
07-23-2002, 08:50 PM #18
- Join Date
- Nov 1999
Steve Hagy, the Hale 8FG is what your talking about, so yes they aleady exist on munincipal apparatus. Waterous has them available also called the S100. Both are rated for 4000GPM. E-One (Oops I said the "E" word) actually just did acceptance tests on eight (8) pumpers for a Corpus Christi area department and they got 4700GPM each. Now thats what I call pump capacity.
Last edited by STATION2; 07-23-2002 at 08:58 PM.Stay low and move it in.
07-24-2002, 12:21 AM #19
Just curious, what were these pumpers officially rated at and were they all delivered to one FD?
07-25-2002, 08:26 PM #20
- Join Date
- Aug 2001
The comments from Syracuse FD are very well taken. SFDs equipment selection, etc definitely deserves attention. If somebody can move big water, it's SFD.
However, on the whole, I still think that the trend to 2000 gpm + pumps is unnecessary.
I think one, there is a lack of understanding of centrifugal pumps and pump curves. Centrifugal pumps can pump an infinite number of flow/pressure combinations from 0 flow/max pressure(churn) to max flow/0 pressure and that curve is very wide. A 1000 gpm pump curve could be out as far as 3000 gpm; 2000 gpm out to 4000+ gpm. There is a lot of overlap in the flows available.An issue that hasn't been mentioned is how far oversized a 2000 gpm pump is for a room and contents fire. Centrifugal pumps flow over a wide range, but they are not equally as efficient - in fact they are very inefficient at low flows. As an example, a typical 1000 gpm could have its best efficiency at 2000 gpm or so. At that flow, the pump is most efficient at turning HP in flow/pressure. Take that 1000 gpm pump and flow 250 gpm and its not very efficient - guess where all the wasted energy goes - heat buildup, vibration, shaft deflection, etc. - those aren't good. And if that 1000 gpm is most efficient at 2000 gpm, that 2000 gpm pump is going to be most efficient maybe at 3000 gpm or so. So you've got a pump that is really built to flow 3000 gpm and your flowing a couple hand lines off it most of the time? That big pump wants to flow some big water and it's just sitting there with its big implellor and case, just churning most all of that water.
The big issue though is that just can't drop a 2000 gpm in for a 1000 or 1250 pump, no change in water supply, no supply line change, no discharge change, etc. and expect big flow increases - it just isn't going to happen. A centrfigual pump will balance it self out on its pump curve based on the supply and suction and discharge conditions.
I took a mid-rise office complex I'm working on - replacing the sites two fixed 750 gpm fire pumps. The standpipes were designed for 500 gpm @ 65 psi. Instead of that 750 gpm, I dropped in a 250, 500, 1000, 1500, and 2000 gpm pump. Here's the flow out of the top two outlets:
250 gpm pump - 390 gpm
500 gpm pump - 510 gpm
750 gpm pump - 513.1 gpm
1000 gpm pump - 513.6 gpm
1500 gpm pump - 514 gpm
2000 gpm pump - 514.2 gpm
In practice - the 500 right through to the 2000 gpm are going to supply about 510-515 gpm - that's it. And where are most FDs with the bigger pumps - same water supply and same supply line - your done right there, even if you increase the discharge, the water supply and supply line will limit the pump. Look at an industrial pumper - typically 3 - LDH intakes - where are all these LDH intakes on the big municipal rigs? Single 5"? That's good for a 1000 gpm pump, but for a 2000? Your just going to choke the 2000 down to the same performance you get out of a 1000-1500.
And HP - the Hale 8FG will do 3,800 gpm off a hydrant with 430HP and 4,600 gpm with 500 HP. Come on, we really are flowing 1000-2000 gpm at most with our 5" - those 300-350 HPs mid-range diesels can move all the water we can typically supply and discharge. On the whole, there is no doubt that from a pumping standpoint, the fire service would be more than well equipped with 330-350HP mid-range diesels with MD trans and a 1250 or 1500 pump and the ability to lay dual LDH.
We need to start curbing our $$ diet in the fire service. Read the report on firefighter fatalities - same firefighter fatality rate in 2002 as 1977? How much have we spent on NFPA 1500, NFPA 1901, etc. in the name of safety or "performance"? Firefighters are still dying at the same rate after we've gone back time after time to the public, we need more $$ for this, we need $$ for that. All we are doing is taking money from our local taxpayers and sending it to Ocala, Florida or Appleton, Wisconsin, etc. That's great for Ocala or Appleton, but what about our communities? What is the community really getting for that 500 HP/2000 gpm on that premium chassis beyond what they would get from a 330HP/1250gpm on a mid-range chassis?
And one last real world example. In the summer of 1999 the Holyoke, Massachusetts FD fought a 9 alarm fire which destroyed 11 buildings inlcuding a large historic Church - 17 engines and 7 ladders with mutual aid. This is a modern - day conflagration. If you know Holyoke, you know it is an old turn of the last century industrial city. It has a very good water system - if the FD tapped into the bigger mains, 15,000 gpm+ could have been available. How much did they flow - water dept data indicated about 3,300 gpm total - 17 engines, 15,000 gpm possible and 3,300 gpm was flowed. Now that is avg water dept data, but even if we up it to 5,000 or so, and say that only half or 8 engines were actually pumping, that's a wopping 600 gpm/engine. So here it is - a BIG fire, this is supposedly why we're buying these 2000+gpm pumps now. Let's get down there and say that only 4 engines were pumping - guess what 1250 gpm/engine - no problem for a even a 1000 gpm. So, in reality, here is a modern-day conflagration and if you look at our supply lines and disharge configurations, we could fight it with 4 - 1000's on commercial chassis's.
What benefit would it have been if those 17 engines were all 2000 gpm - ZERO. If you really want to use the 2000 gpms, you would have to lay some considerable length of supply to get to the bigger feed mains - you probably need to tap at least 24" mains if you want to start moving beyond 5,000 gpm and probably a 36" for 10,000 gpm +. And how are you going to move 2500 gpm or so a few cities blocks at least to these big pumps - with 5"? A 1000 ft. of 5" flowing 2500 gpm - 288 psi of friction loss. 5" is tiny for a 2000 gpm pump.
We haven't even maxed out a 1250 gpm and now we say we need 2000 gpm or more with 500 HP engines - I doubt very much the public is getting anything out of these purchases.
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