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  1. #1
    Catch
    Firehouse.com Guest

    Question Single-stage vs. Two-stage pumps

    My small department is considering purchasing a second pumper and due to lack of funding we're looking at an older, used unit. As we're vollies and relatively inexperienced with various pumps, I'm curious what you guys have to say about the pros, cons, and major differences between single stage and two stage pumps. Thanks for your help!!


  2. #2
    Dalmatian90
    Firehouse.com Guest

    Post

    Don't think it would much matter!

    Buying a new truck, there is no reason for a two-stage pump unless you have hi-rises or some other reason you need to pump relatively large flows (500gpm or so) at high pressure to overcome gravity...

    Buying used, shouldn't make a difference, if that's what it has OK then...just remember to put the pump in volume instead of pressure and it'll act like a standard fire pump hydraulics wise.

  3. #3
    Jim M.
    Firehouse.com Guest

    Post

    If you're a small dept and training time is an issue (be a miracle if it isn't) stick with the single stage if possible. There are fewer things to teach and fewer things to worry about with the single stage. While the two stage has it's uses, it does require a skilled operator to take advantage of them. The amount of operator skill required to run the single stage is less.

  4. #4
    ADSN/WFLD
    Firehouse.com Guest

    Post

    I'm with Jim, I've seen many a fire where the engineer can't flow the volume he wants. only to find out that he was pumping in pressure. I have yet to see an engine wear out from pumping a single stage pump.

  5. #5
    jj1967
    Firehouse.com Guest

    Post

    I'd go with the single stage. I've operated both (actually I've also run a three stage on a 57 International, but thats another story). With a modern diesel engine I don't see a big need for a two stage, unless as someone already mentioned you might have to pump to high elevations. We just keep both our two stage pumps in volume. Most of the time you could get away with pressure...but if you lay out that third line and have to switch things can get dicey.

  6. #6
    J Almon
    Firehouse.com Guest

    Post

    We had a two stage 750 gpm pump on an old engine, and switching between single and two stage was no big deal. The manual suggested lowering discharge pressure to 50 psi and slowly rotating the vane control. It said to move to the volume position if flow was over 50 percent of capacity, so we swapped back and forth quite a bit. It only took about 20 seconds and as long as everyone knew the pressure was going to drop for the change, it was never a big deal.
    Get whatever will serve your needs. You'll have to evaluate that based on your coverage area. Just remember, whatever you buy, you'll probably have it many years!

  7. #7
    JohnM
    Firehouse.com Guest

    Post

    There is one factor that put me in favor of two stage pumps. When we were asking the same questions a few years back, I called the Waterous servive department. One thing they told me was that a single stage pump will heat up almost twice as fast a two stage when water is not flowing. Of course we know that we should circulate or establish water flow to prevent this, but some of our operators forget (I know training). A two stage will allow this abuse for a longer time before the water gets hot enough to cook things. Just my two cents!

  8. #8
    DD
    Firehouse.com Guest

    Post

    I'll take the single stage as long as the engine has the power to pull it. There is less moving parts on the single stage. That results in simplier operation, less things to maintain, and less expensive repair cost. The transfer valves and acutators on two stage pumps can be somewhat tricky to repair, if you do your own work. I would rather have a spring type relief valve than the older governor relief systems. Again, they are more reliable and easier to maintain. I don't have any experience with the newer, computerized, pressure control systems. One thing about buying older, used engines is that you usually get to know them very well from the time spent on repairing and maintaining them. Been there, still doing that.

  9. #9
    CAM
    Firehouse.com Guest

    Post

    The 2 stage pump was developed to overcome the limits of low horse power gasoline engines of the past. A single stage pump behind a suffecient engine in a grlitively new truck will give less problems, reduce training and lower maintenance cost.
    Calling the pump manufacturers is a great idea as they will bend over backwards to help you and not only with their pumps.
    Waterous has always come through with answers to my questions and they believe in teaching also.
    As for a single stage heating up faster... Thats B.S.

  10. #10
    LHS'
    Firehouse.com Guest

    Post

    FDNY's newest 2000 gpm pumpers are coming as two starge pumps. Sometimes pressure is needed, high rises, tower ladders, some times the 2 stage is more effiecient.

  11. #11
    g david moose
    Firehouse.com Guest

    Post

    Originally posted by Catch:
    My small department is considering purchasing a second pumper and due to lack of funding we're looking at an older, used unit. As we're vollies and relatively inexperienced with various pumps, I'm curious what you guys have to say about the pros, cons, and major differences between single stage and two stage pumps. Thanks for your help!!


    ------------------
    dmoose

  12. #12
    g david moose
    Firehouse.com Guest

    Post

    a two stage pump in par is a single stage pump the two cost the same to maintain or repair or overhaul a single stage pump is at its max efficency when it is pumping its cap put it in series and slow that engine down when you want low flows at a higher pressure how often do we pump the cap of the pump?

  13. #13
    jimc1039
    Firehouse.com Guest

    Post

    2 stage is better.

  14. #14
    Big Jim
    Firehouse.com Guest

    Lightbulb

    Catch:
    Having worked with both for many years, I can safely say that when buying a used or refurbished pumper, it is more important to be sure that the pump is in good working order than to be extremely worried about the number of stages and other minor details (insist on copies of maintenance and repair records and the qualifications of the maintenance / repair personnel).
    However if the number of stages is going to worry you, let me put your fears to rest.
    When you purchase you "new" used pumper, make sure that you get the original operators manuals for the pumper, engine, transmission, pump, generator, etc. The operators manual should give you detailed instructions on how to properly operate the equipment, as well as critical maintenance information that will help you keep the equipment operating relatively worry-free for years to come. If available, get technical repair manuals with it also for even more detailed information. Also, if you don't already have a current copy, contact IFSTA at (800) 654-4055 or www.ifsta.org for ordering information for "Fire Department Pumping Apparatus" which you can use to help teach your pumper operators how to better operate their pumps.
    As to which type of pump is better: single stage or multiple stage? I work for a department in a mid-size city in South Carolina. We have both singles and doubles in our front line and reserve apparatus, including a 2000 gpm single stage in our platform aerial! I work with both on a regular basis and find either to work exceptionally well. However, before coming to work here, I volunteered in a small town / rural department for 10 years, driving & operating for most of those years. We had a two stage 1st out with a single as reserve, both 750 gpm. The biggest problem we ever had was the changeover valve sticking because it stayed in "volume" (parallel) all the time (if we had pumped in series and in parallel weekly, we probably wouldn't have had that problem). We had excellent service leaving the two stage in parallel, and the only time we needed to use series was when we had to pump a long relay (dual 2-1/2" lines before we got 5"). If you want to get more information, email me at: jtrentonthomasjr@hotmail.com
    or visit our website: www.beaufortfiredept.com
    I hope this information helps you.
    Trenton

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