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  1. #1
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    Default Why does 1,250 GPM seem to be the "Standard" size pump?

    Why is 1,250 GPM the standard size pump on stock units and commercial chassis? Why not 1,000? Why not 1,500?


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    Not totaly sure... but I would guess becasue of cost. With most pump mfg's the pump body is the same for 1250 gpm pumps up to 2000 gpm pumps. The only difference is the amount of intakes and disccharges....all of wich cost money...so the 1250 is the cheeper way to go, and if you choose a rig and want to up grade, theres probably less engineering.
    but like i said...i'm not totaly sure.
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    Used to be that specing a 1500gpm pump would put you into a custom chassis, but I don't know if that is still the case.

    C6

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    I'd say "standard" is a matter of opinion, subject to what you're most frequently exposed to. I doubt any firm/Dept (outside of U.L.) has a unbiased sample size to say with credibility what the most frequent size (arithmetic mode) is.
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    When some manufacturers are building stock or program trucks they use a pedestal style pump and build the suction and discharge manifolds themselves. I believe it's cheaper but usually limits the GPM to 1250. At least that's what I've noticed around here.

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    Quote Originally Posted by VanIsleEVT View Post
    When some manufacturers are building stock or program trucks they use a pedestal style pump and build the suction and discharge manifolds themselves. I believe it's cheaper but usually limits the GPM to 1250. At least that's what I've noticed around here.
    I believe that's the case with Waterous (a CX is rated to 1,250 gpm) but a DSD from Hale will do 1,500 gpm. I'd have to look at the Darley catalog to see where they end up as far as a rating, but I believe a PSM will do 1,500 as well.

    Obviously, they all made a pedestal in a higher price range that will do more volume.
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    You are right and I should have clarified the pump models. Having said that, trying to get a Hale PSD to pump 1500 with one 6" suction is impossible where a typical big pump rated at 1500 will do it no problem.. I believe the CX is rated at 1500 now WITH a ram horn suction manifold.

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    Default Pump Rating

    I know with Hale they have two sizes of big mid-ship pump castings. The smaller series of pump is rated from 750 up to 1,250 gpm. The bigger pump is rated from 1,250 up to 2,000 gpm if you have enough engine and enough discharges. So the 1,250 gpm rating is the max. you are going to get with the smaller, less expensive pump and a smaller less expensive engine and transmission. So it becomes kind of a break point for the less expensive rigs.

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    Both my current and previous department use the "big-body" pumps, Hale Q-max or Waterous CSUY which are capable of 2000gpm+ but we had them rated @ 1250. Mainly, for the ease of pump testing, 1-6" instead of using two, and to have room for error during the later years of the pumps life.

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    Quote Originally Posted by Command6 View Post
    Used to be that specing a 1500gpm pump would put you into a custom chassis, but I don't know if that is still the case.

    C6
    Most commercial chassis can take a 1500 GPM pump. I've seen some bigger commercial chassis with up to 2,000 GPM pumps.

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    Quote Originally Posted by txgp17 View Post
    I'd say "standard" is a matter of opinion, subject to what you're most frequently exposed to. I doubt any firm/Dept (outside of U.L.) has a unbiased sample size to say with credibility what the most frequent size (arithmetic mode) is.
    I'm not saying standard as in most custom apparatus. I was more talking about program/stock trucks on commercial chassis.

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    Quote Originally Posted by VanIsleEVT View Post
    You are right and I should have clarified the pump models. Having said that, trying to get a Hale PSD to pump 1500 with one 6" suction is impossible where a typical big pump rated at 1500 will do it no problem.. I believe the CX is rated at 1500 now WITH a ram horn suction manifold.
    My department has a DSD in a top mount pumper, and I'm fairly confident it makes 1500 gpm using only one six inch suction. I need to check into this.
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    Default Not sure I agree

    Did a quickie survey of 100 engines shown on 7 different manufacturers recent delivery web sites. Even searched for "Commercial Chassis" and still found the majority of engines being built with 1,500 gpm pumps. The main difference between the commercial chassis and the custom chassis deliveries seemed to be the size of the engines. Most of the commercial deliveries had engines in the 250 to 350 HP class, while most of the custom deliveries were sporting 400+ HP. The engine size is a big factor in matching the pump pump size. A 1250 gpm pump operating at 150 psi needs an input power of 104 HP if the efficiency of the system could be at 100%. Most transfer case and pump combinations are closer to a 50% efficiency, so a minimum engine size would need to be close to 210 HP. If you examine the torque and horse power curves for the smaller commercial engines, you will see that they are not able to supply the required torque and horsepower demands over the wide rpm range needed to operate a fire pump from 150 psi up to 250 psi.
    1500 gpm pumps accounted for about 65% of the sample. About 20% of the deliveries had pumps of 2,000 to 3,000 gpm. The 1250's were only 13% of the deliveries that I sampled.
    The two 3,000 gpm pumps were both on aerial apparatus with 500+ HP engines.
    Last edited by KuhShise; 06-04-2010 at 05:29 PM.

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    Wow, I'm impressed! Did you check the manufacturer's stock/program trucks?

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    Another thing that could be looked at would be if main operation is from hydrant.
    How much water will the hydrant system supply.
    Example:
    Why get 1500 GPM pumps when you only get 1250 GPM from local hydrant system.
    Just thoughts.
    Ray

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    Quote Originally Posted by RFREY1 View Post
    Another thing that could be looked at would be if main operation is from hydrant.
    How much water will the hydrant system supply.
    Example:
    Why get 1500 GPM pumps when you only get 1250 GPM from local hydrant system.
    Just thoughts.
    Ray
    That pump is rated at 1250 at 150psi at draft. At 200 psi that pump is rated at 75%. at 250 psi it is rated at 50%. The larger the pump the higher that 75 and 50% is.
    On a hydrant (pressurized water supply)you will achieve more then the rated GPM.
    If the hydrant is only giving you 1250 and you need more dual hitch the hydrant. or take a line from another hydrant on another main. The larger the rating of the pump the less wear and tear on the pump is what i have always been told.

    I have always heard that the only difference between a 1250 and a 1500 is the number of discharges. They are the same castings and pump housing just differences in intake manifolds and discharge manifolds. Does anyone know if that is true or just an old wise tale?

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    When you start talking about a Hale Q-Max the pump is the same from 1,250 up. The difference is the horsepower in front of it and the number/size of discharges. For example, our latest pumper is rated at 1,500 gpm because that's all our draft pit can handle and no one wanted to mess with two hard suctions to draft above that. In reality, it could be rated at more because of the engine choice we made.

    Regarding the 1,250 gpm demo trucks. Perhaps they are trying to split the difference on their markets. Some departments would say that 1,500 is way more than they need while others would say a 1,250 would probably work. This way it could appeal to a larger market. Just a thought.
    Last edited by FFWALT; 06-06-2010 at 02:13 PM. Reason: Got off the tangent.
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    Quote Originally Posted by RFD21C View Post

    I have always heard that the only difference between a 1250 and a 1500 is the number of discharges. They are the same castings and pump housing just differences in intake manifolds and discharge manifolds. Does anyone know if that is true or just an old wise tale?
    Look at the Hale, Waterous or Darley, websites. Different models have different ratings. For example, Q-flo can do 750 to 1250, Q-max 1250 to 2250. It is dependant on intakes, discharges, Engine HP, etc etc...

    Most of the demo trucks are going for a price point in the market. Most people are not in the market for a demo AND big spenders so they do not have high priced options on them.

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    Quote Originally Posted by KuhShise View Post
    Did a quickie survey of 100 engines shown on 7 different manufacturers recent delivery web sites. Even searched for "Commercial Chassis" and still found the majority of engines being built with 1,500 gpm pumps. The main difference between the commercial chassis and the custom chassis deliveries seemed to be the size of the engines. Most of the commercial deliveries had engines in the 250 to 350 HP class, while most of the custom deliveries were sporting 400+ HP. The engine size is a big factor in matching the pump pump size. A 1250 gpm pump operating at 150 psi needs an input power of 104 HP if the efficiency of the system could be at 100%. Most transfer case and pump combinations are closer to a 50% efficiency, so a minimum engine size would need to be close to 210 HP. If you examine the torque and horse power curves for the smaller commercial engines, you will see that they are not able to supply the required torque and horsepower demands over the wide rpm range needed to operate a fire pump from 150 psi up to 250 psi.
    1500 gpm pumps accounted for about 65% of the sample. About 20% of the deliveries had pumps of 2,000 to 3,000 gpm. The 1250's were only 13% of the deliveries that I sampled.
    The two 3,000 gpm pumps were both on aerial apparatus with 500+ HP engines.
    One of the reasons Hale and Waterous have developed new drive systems(and gearing)to run BIG(1250 plus)pumps with the "mini-me"engines. 210-250 horse will run a LOT of pump these days. Many variables but I think the 1250-1500 range was set to appeal to the largest buying audience. It's not very often you use a 1500 pump to capacity. If you NEED it it's nice to have the capability. T.C.

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