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Thread: pump help

  1. #1

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    Default pump help

    I could use some help. I took my pump class years ago, but I sort of recall a general rule as to how many discharges there would be for a certain gpm. In other words, something like 1000 gpm pump would have 5 discharges and so on. Does this still apply?
    We're looking into a new pumper and would like as many discharges as possible for preconnects, but I'd rather stick with a slightly smaller gpm pump due to the horrible flow we get from our hydrant system. Hypothetically, can I spec a 1000 gpm pump with, say 9 discharges (3 crosslays, 1 in hosebed or on rear of truck, 2 on each side of truck, and 1 on front bumper)?


  2. #2
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    Cool Answer.....

    Yes it still applies.

    Typically for every 250 g.p.m. pump rating 1-2 1/2" discharge is used. So for what you raised here, a 1,000 g.p.m. Engine would have 4-2 1/2" discharges and a steamer intake of 6". It also gives how many 4" or larger discharges a pump can supply. An Example is like this: Truck (Ladder): 1,250 rated pump; 5-2 1/2" discharges, but can also have a 4" discharge. Our Truck is set-up like this: 1,750 g.p.m. rated pump; discharges are arranged like this..... 2-1 1/2" discharges w/ 1 3/4" hoselines, 2 1/2" discharge wyed to 2-1 1/2", 3-2 1/2" discharges and 1-4" discharge.

    However, the Department doesn't have to follow this...... IFSTA Pumper gives the recommended specs. Also most manufacturer's are very helpful...... since after all, they are the Specialists.
    "Be LOUD, Be PROUD..... It just might save your can someday when goin' through an intersection!!!!!"

    Life on the Truck (Quint) is good.....

    Eat til you're sleepy..... Sleep til you're hungry..... And repeat.....

  3. #3
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    Default

    Quote Originally Posted by chief888 View Post
    I could use some help. I took my pump class years ago, but I sort of recall a general rule as to how many discharges there would be for a certain gpm. In other words, something like 1000 gpm pump would have 5 discharges and so on. Does this still apply?
    We're looking into a new pumper and would like as many discharges as possible for preconnects, but I'd rather stick with a slightly smaller gpm pump due to the horrible flow we get from our hydrant system. Hypothetically, can I spec a 1000 gpm pump with, say 9 discharges (3 crosslays, 1 in hosebed or on rear of truck, 2 on each side of truck, and 1 on front bumper)?
    No, it generally doesn't apply anymore.

    Yes, you can spec 9 discharges as long as the pump has the ports available

    New pumps with more powerful engines and better performance are rated much higher than the pumps of yesteryear. Back in the 80's and earlier it was a pretty common rule of thumb. Most modern fire pumps have 3" or larger outlets on the main pump body, what size and type of valve and thread will determine its performance. Cast pumps have many discharge ports, however, only a few are typically used.

    Our new 1250 GPM pumper will have a Hale Qflo pump. The pump is capable of greater than 2000 GPM from a sufficient positive water source. It will have (3) 2 1/2", (3) 3" and (2) 1 1/2" discharges for a total of 8 discharges plus a 3" deluge riser.

    Using Hale's rating table, we can and will be able to greatly exceed what NFPA uses as their formula, especially on a Hydrant.

    NFPA 1901 1999ed. still rates the discharges as follows:
    2-1/2” = 250 GPM
    3” = 375 GPM
    3-1/2” = 500 GPM
    4” = 625 GPM
    4-1/2” = 750 GPM
    5” = 1000 GPM
    6” = 1440 GPM

    Don't shortchange yourself on a small pump just because you have bad hydrants. If you will ever work as a drafting engine, consider 1500 or greater. You will find the difference in price from one rating to the next within the same pump model family as very little.

    Good reading here...Especially on Pg. 37-39

    http://www.haleproducts.com/_Downloa...on%20guide.pdf
    Last edited by MG3610; 02-11-2007 at 07:10 AM.

  4. #4
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    Chief
    I would agree with MG, it doesn't apply any more. NFPA 1901 basically requires a few minimums be met and after that, if you can design it/plumb it, etc. you can have the discharges configured the way you want them. Basic minimums are a minimum of 2 - 2 1/2" outlets on pumps rated > 750 gpm and you have to have a set of discharges (2 1/2" or greater) that will discharge the rated capacity of the pump using standard flows for each discharge size. Nothing stops you from going beyond the minimums if you can plumb it.

    When you horrible flow from your hydrants, what are you talking at 20 psi residual at the hydrant? and do you ever draft?

  5. #5
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    Default

    NFPA 1901 requires is that you have sufficient discharges to meet the pumps rated flow. The numbers MG has listed is identical to that in the standard. Basically, if you have a 1,000 gpm pump, you'll have to have as a minimum of 4-2 1/2" discharges, or even just 1-5". The preconnects are extra and don't count toward that number.

    Like others have said, don't short-change a bigger pump. The cost difference is not that big of a deal. Our new pumper/tanker came was bid with a 1,250 pump, we upped to to the same brand 1,500 gpm at no extra cost. We then changed brands and upped it to a 1,750 and saved over $3K.

    Consider going with the biggest pump your engine will push. For one thing, it's going to go toward your ISO figures (pump capacity must meet the FD's rated fire flow). The biggest reason in my book is for the versatility. With our set-up, we can fill multiple tankers at 500gpm+ from draft. We can also flat flow the LDH if we're close enough to a water source. Most of our houses have a pond within 1,000' of the residence, so we'll drop dual LDH and pump to the attack engine with the new truck (remember, the rated flow of the pump is not it's limit by any means).

    I'm with you on multiple pre-connects as well. One of our engines has 4-1 3/4" and 2-2 1/2" preconnects. The pumper/tanker has 3-1 3/4" and 2-2 1/2". Plan for the future and what works for your department and you won't go wrong.

  6. #6

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    Thanks everybody. I really appreciate the input.

  7. #7
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    Cool Why it still matters to use......

    Being a Contract Fire Department and working for the D.O.D. the number of discharges is still in effect. It's kinda weird that we are held to Federal Standards, State Standards and well as our Local Standards.

    Even at our County Fire Department the number of discharges still applies. Seems to me like it's a regional thing....... Go figure........
    "Be LOUD, Be PROUD..... It just might save your can someday when goin' through an intersection!!!!!"

    Life on the Truck (Quint) is good.....

    Eat til you're sleepy..... Sleep til you're hungry..... And repeat.....

  8. #8
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    Exclamation Minimum standard

    NFPA 1901 (as is any NFPA standard) is a minimum standard, and therefore it specs only what is needed to get the rated flow of the pump out of the truck. Generally for every 250 gpm a rated pump will flow, you have to have one 2 1/2" in outlet. So a 750 gpm pump must have a minimum of three 2 1/2" outlets, a 1000 gpm four, a 1250 gpm five, and so on up. Anything past the minimum you want to spec, have at it.
    Pray for the dead, fight like hell for the living! - Mother Jones

  9. #9
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    Default Pump Flow

    NFPA requires that "Discharges outlets of 2.50" or larger shall be provided to discharge the rated capacity of the pump at the folw rates in table 16.7.1. (NFPA 1901, 16.7.1, 2003 edition).
    Table 16.7.1:
    Outlet size Flow Rate
    2.5" 250
    3.0" 375
    3.50" 500
    4.0" 625
    4.50" 750
    5.0" 1000

    So you would need to add up all of you 2.5" or larger discharges, and it needs to add up to the rated capacity of the pump. Preconnects at least 2.5" would be able to be included.

  10. #10
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    What CE11 said was right on!

    Since we are both in southeastern Pa, we pretty much have the same weather. We used to run our pumps dry many years ago until I spoke out of turn many years ago against our Cheif Engineer.(I was young and dumb 20 years ago) I asked our Chief at the time within ear shot of our Chief Engineer why we ran our pumps dry, and still had frozen valves and drains. When he gave me the answer, "that's the way we have always done it" I explained to him it would take a lot longer to freeze the water in the pump if the pump was wet and then when recirculating it would take even longer to freeze a 1000 gallons of water he agreed and we have run wet pumps since then.

    You however must be careful on Quints and Engines that do not care much water. For example we overheated the pump on our Quint 15 years ago when it was very cold out. We where on a call for several hours, the driver arrived and recirculated the pump at idle (50 PSI) for several hours and did not think about the pump generating heat. When they where ready to return to the station, that's when they relized that the 400 gallons of tank water had been heated to hot "tea" water. Moral of the story is you can over circulate your water.

  11. #11
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    Quote Originally Posted by Chief1FF View Post

    You however must be careful on Quints and Engines that do not care much water. For example we overheated the pump on our Quint 15 years ago when it was very cold out. We where on a call for several hours, the driver arrived and recirculated the pump at idle (50 PSI) for several hours and did not think about the pump generating heat. When they where ready to return to the station, that's when they relized that the 400 gallons of tank water had been heated to hot "tea" water. Moral of the story is you can over circulate your water.
    The chief makes a great point here. Although I haven't gotten around to doing it, the reality is, you can. Anyone who has hung around Supplee Bros. in Oreland, Pa., who represent Waterous Co. for service, has heard story after story about that very thing, along with just about anything else we can do to a fire pump. Briefly, the smaller the tank, the quicker you'll heat it up.

    My favorite story is one that happened in our own station. We had a deputy chief many years ago who believed that you could churn water indefinitely, no need to circulate. He would give me all kinds of grief when I did it. One time at a drill he was hanging around the pump panel, so I made it a point not to circulate. He had his hand on a discharge that had an 1-1/2 line coming off of it, but not in use at the moment. When the crew of the line was ready, he instructed me to open it up. When I did, he got himself a bit of a burn on the palm of his hand. After yelling a bit, he asked what happened. I just told him that what happened is what can't possibly happen. Never had a problem with him again.

    In another thread a brother was complaining about being expected to know something about physics in order to operate an aerial ladder. The plain fact is that everything we do whether it be pumping water, raising ladders or anything else is rooted in basic physics. You know, the stuff we learned in high school if not earlier.

    Stay safe out there everyone goes home.

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