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Thread: variable speed pumps

  1. #31
    Oyagoi yerrag's Avatar
    Join Date
    Jul 2013
    Manila, Philippines
    Mike, when my static k1 media bed is on its way to being clogged up but still can let a lower flow through, I would turn off my primary flow pump and turn on the other flow pump. That other pump has a lower flow rate, and at the lower flow rate, I would be able to continue my pond and filter operation, as it keeps the water level of the last filter chamber, where the pump draws water from, from getting too low and turning off the pump (thru a level switch). I would think about your Flow Friend each time I do this. Hope you are finding more and more handy uses for it.

  2. #32
    Honmei MCA's Avatar
    Join Date
    Dec 2003
    I am very glad to have that pump. It is so nice to dial in RPM, read the power consumed, and see the impact on the shower flow rate. With that capability and feedback, you can make decisions about desired flow rates for which time of the year.
    Koi keeping is not a belief system; it is applied science with a touch of artistry.

  3. #33
    Join Date
    Jul 2005
    Fremont, CA
    Quote Originally Posted by yerrag View Post
    That's very interesting Rich. That could only mean the people installing the pump weren't really looking at the pump curve chart, right? It would have told them that running at a lower head is a no-no. But of course, Sequence had to "upgrade" the motor because many engineers (if you still call them engineers) simply can't RTFM. And everyone else had to put up with a motor that costs more or uses up more power to accommodate the imperfect world. Which is one good reason pump manufacturers don't like to personally recommend pumps to users as users will just as easily mess up on designing and installing their pump systems and come around and blame the pump manufacturer for it. Pump dealers will just let you browse their pumps, and when you ask, provide you with literature, and let you decide which pump to use.

    Thanks for sharing this. It's so hard to find charts that give you the BEP. Why is that?

    Rich, what exactly are VSC and VSP pumps? Would appreciate a bit of 101 on this topic.

    I'm not quite in agreement with using ball valves for regulating flow. Their use is more for on/off operation, as with gate valves. They can do the job, but not do it very well. Eventually, they will not fully close because some deposits/sediments block the closure. And with ball valves, they can't regulate in small increments. But they will do for the time being. I read about globe and diaphragm valves doing flow regulation well, but they are hard to find and they must cost a lot. I saw wye valves on flexpvc.com. They're pricey:

    Product Listing PVC-Valves-Wye-Pattern

    I can understand why we end up settling with ball valves.
    Service factors (SF) are selected to accommodate different conditions! Heavy starting load won't require as much of an SC as loads that droop/surge for long periods of time! Increasing the SF was an effective way to handle hobbyists & dealers inexperience with pump plumbing design! Most manufacturers do it that way!

    Variable speed controllers(VSC), Variable speed pumps(VSP).

    There are a few curves not included on the Design curves we see! The first, of course is the design point you refer to, then the efficiency curves drawn on the Same graph as the p/p design chart. Those curves would serve hobbyists interested in selecting pumps we are discussing here!

    The best way to select the pump is to determine the head required to achieve a certain flow! using that those readings, mark the point where they intersect and that is the system design point. Mark the chart at the zero flow/vertical(static) head point along the left hand side of the chart. Draw a line from the zero(VH) flow point Straight through the system design point to a point where you no longer want to consider as the BEP. Now you can compare a pumps BEP to see how it will fit your system. I like to pick a pump that will provide a little extra flow to deal with dirty lines & such!

    I wish they would come up with a way to deal with a confused mind!

    An email dropped to a manufacturer will get you the pumps BEP and anything else you can think of! (Related to that pump!)

    Another thing! When replacing a pump, measure the head and vacuum pressures while the present pump is in operation! (Best to do that now so you will have the readings available if the pump dies!) That's all you need to draw the system curve so you can select the replacement pump! You never know if you made the best selection originally and now would be the time to select a different pump, if that's needed

    For winter when you have a lower head, a smaller pump might be an excellent idea! Using the system design curve to determine the pump you need to help to make that decision!


  4. #34
    Oyagoi yerrag's Avatar
    Join Date
    Jul 2013
    Manila, Philippines
    I wish I could find the BEP info in the curves as easily as you Rich. Trust me, it would be easier for me to get rich panning for gold in the Los Angeles River. What I usually get is a blank stare. I'd be happy if I just get a curve. Sometimes, it's not available. Go figure. This is Manila, by the way. It gets worse when you go to downtown Binondo, to the street called Espelets teeming with pump dealers. They have many pumps displayed, but it all goes downhill from there. The only thing you can do is to ask for the price. You will feel ignored if you ask anymore questions. You're supposed to be the process engineer who knows what pump you need. Then again, the pumps they sell are usually the centrifugal and jet pumps, not the high flow, low pressure pumps we use. Still, there are a few instances where hobbyists would buy a pump from them, and get saddled with a monthly electric bill that's 6x what you would normally be billed using an appropriate pump. Yes, there are many confused minds ha-ha!

    Rich, you lost me with the vacuum and head pressure. How do you go about measuring them? Is it right before and right after the pump?

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