Pressure Tank Size

Discussion in 'Pumps and Tanks Well Forum & Blog. Water is life.' started by jed1154, Jan 22, 2020.

  1. jed1154

    jed1154 Member

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    i have no doubt that we will be purchasing a device. I just don’t know how many pumps we will go through before they agree with what I believe to be a real solution...a better way.
     
  2. jed1154

    jed1154 Member

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    This all makes sense to me. I am trying to relay this information. I am now getting hung up on the back pressure argument. This device introduce his back pressure on the pump. They do not like that. I do not know how to Explain how and why back pressure on a pump is OK for it.
     
  3. Chucky_ott

    Chucky_ott Member

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    Ontario
    Not sure if this explains it but it is an independent resource:

    https://mechanical-marine-systems-e...what-is-back-pressure-in-centrifugal.html?m=1

    Benefit of back pressure in centrifugal pumps:
    - higher back pressure at the inlet of the discharge valve will decrease the power requirement of the driving motor of the pump


    Effects of higher back pressure in centrifugal pumps:

    - flow at the discharge valve outlet is reduced
    - pressure of fluid at the discharge valve outlet is reduced
    - longer time to fill up (tank, container, etc.)
    - longer time to empty (tank, container, etc.)
     
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  4. jed1154

    jed1154 Member

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    So CSV is made in Texas. Who are some companies in the region that are installing these devices? "Water well guys" are nearly as prevalent as roofers and real estate agents. Surely there are more than just a few in this state that support and install these. Where can I find a list of drillers and installers who back this equipment? I'm near San Antonio, a region that has strict standards on wells, I would expect a device such as this to be all over the place in terms of municipalities and drillers using them.
     
  5. valveman

    valveman Cary Austin Staff Member

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    Pump Controls Technician
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    Lubbock, Texas
    Thanks Chuck! The fact that increased back pressure makes a pump draw less power and run cooler is written in every text book and printed on every pump curve. But it is still counter intuitive and only a handful of people have studied this enough to comprehend something that works just the opposite of what our brains tell us. You can find where I have been explaining this over and over for 27 years. Yes there are a few installers who understand CSV's. I think 5% maybe overly optimistic. In your area you can call Preferred pump. They are just one of many of our distributors who stock and sell CSV's. Out of a thousand of their installer customers, they may have five that use CSV's on a regular basis, and only one of them will understand how the CSV and pumps really work together. Even on this forum you can find many pump installers who are adamant that back pressure is bad, which shows how adamantly wrong they are. There are only two or three good installers on this forum who really understand what they are doing.

    As a pump man myself, it is embarrassing to admit that 98% of the people in this industry are barely qualified to run a pump hoist up and down, and have no clue how the products they install actually work. Even though 98% think back pressure is bad, it doesn't make it right. It just embarrasses the 2% of us who really know how pumps work. I feel I have to apologize for the vast majority of so called "pump professionals". I don't blame people for listening to what their neighbor says instead of the local pump guy. Searching the Internet for answers and relying on your own intelligence is the only way to keep from getting taken by someone who says cycling is OK, or is "adamant back pressure will destroy your pump". LOL!

    Gary Kirkham in Uvalde is one of those who understands pumps. Here is a picture of one system he did many years ago.
    http://forum.cyclestopvalves.com/index.php?topic=2334.0

    I have said many times everything they need to know is on the pump curve. If a pump man cannot read a pump curve and understand this, he really has no business being in the pump business. Understanding this natural phenomenon can help a pump man pick the best pump for the job, like this pump that draws 5.2HP at 55 GPM and only draws 2.2HP at 5 GPM while still running at a constant 3450 RPM. At 55 GPM the pump is working at 104 PSI back pressure. Back pressure is what makes a pump work. Increasing the back pressure by about 50 PSI reduced the horsepower from 5.2 to 2.2. How can that be a bad thing?
    45S50 curve jpeg.jpg
     
  6. Texas Wellman

    Texas Wellman In the Trades

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    Owner of a Water Well and Pump Repair Business
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    SE Texas-Coastal
    You better find out exactly what pump and the water level you are pumping from. A lot of high flow pumps won’t make much pressure and high head pumps won’t make much flow.

    5 HP is about as big of a motor as you can get for a typical 4” well. I suspect you will need to change the wet end.
     
  7. valveman

    valveman Cary Austin Staff Member

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    Building back pressure against a restriction is what pumps are made to do. The amount of back pressure needed from the pump depends on the amount of restriction. As TW says, "high flow pumps won't make much pressure and high head pumps won't make much flow. We never did figure how much back pressure your pump needs to make to supply water as needed. From the curve I posted above, that 5HP will produce 50 GPM at 275', which is the same as 119 PSI of back pressure. You will need 50 PSI of this pressure at the surface to supply the houses, so the other 69 PSI can supply the lift, meaning the water level can't be lower than 160' deep. If the water level is deeper than 160' and/or you want more pressure at the houses than 50 PSI, you will need a larger pump. And again like TW says, 5HP is the largest single phase motor you can get in 4" casing. But I did not see where you gave the casing size? If the casing is 5" or larger a flow sleeve would be recommended, and or a larger pump is possible.

    So, as you can see from the curve, this pump was designed to run at 104 PSI back pressure. And this pump can only build a total of 149 PSI back pressure. It is not the back pressure that hurts a pump. It doesn't see much difference between the 104 PSI it is suppose to run at all the time, and the 149 PSI that a CSV would cause. As long as there is enough flow to keep the pump and motor cool, the back pressure is a non issue. And it is the back pressure than determines whether the bypass in the CSV3B2T is allowing 2 GPM or 8.7 GPM. The 5 GPM is just the average. With only 10 PSI difference in the back pressure the pump can build and the shut off point of the pressure switch, the CSV allows 3.1 GPM to bypass. With 130 PSI differential the CSV allows 8.7 GPM to bypass. In this way the CSV allows more flow to bypass when using a high head pump with multiple impellers that may need 8 GPM for proper cooling. But the same CSV will only allow 3.1 GPM with a single impeller low head pump because that pump doesn't need nearly as much cooling.

    So, the non-closing bypass in the CSV works from 2 GPM to 8.7 GPM, depending on the differential pressure of the pump you are using. In this case if we say the water level is at 150', we subtract the 150' from the 345' max the pump can build. 345 - 150 = 195'. This means the most pressure that will be on the inlet side of the CSV is 84 PSI. With 84 PSI coming into the CSV and the pressure switch shutting off at 60 PSI, there is only 24 PSI differential across the CSV. With 24 PSI differential pressure the minimum flow through the CSV will be almost exactly 5 GPM. At 5 GPM minimum all the scenarios we discussed would be correct and the pump would have about 3 times more flow than needed to stay cool. The higher the back pressure on the CSV the more cooling flow you get for the pump and motor, which is just another counter intuitive thing many installers have a hard time wrapping their head around.

    Differential Pressure chart.jpg
     
  8. jed1154

    jed1154 Member

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    Location:
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    I am going to get you guys the model number of the pump installed and the depth at which is it sitting and the water level. I have all of this information if I can dig it up. We need to really pin down specifics now. Thanks everyone.
     
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  9. jed1154

    jed1154 Member

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    Feb 11, 2008
    Location:
    Texas
    OK, folks. This is the moment we have all been waiting for. Well, for me anyway. I spoke to the company that installed my pump and got all of the info for it. Interestingly they have not only heard of Cycle Stop Valves, they "install them all the time". This is great because I really love these guys. Theyve always done stellar work for our properties. HOWEVER.....they recommended against it for my application. They said they do NOT recommend them for pumps that are on PVC and certainly not one of this size without a cooling jacket. They won't install one citing possibility of rupturing the PVC. The pump has to capability to produce more than the PVC can handle if we throttle it.

    My Info:

    PUMP: Grundfos 60S50-9
    MOTOR: Franklin 224303
    Pump is at 361' 6" casing
    PVC to pump is schedule 120
     
  10. Reach4

    Reach4 Well-Known Member

    Joined:
    Sep 25, 2013
    Location:
    IL
    Nice info. Grundfos 60S50-9 60 gpm 5 HP. See that shutoff PSI?Not enough to bother schedule 40 PVC, let alone schedule 120 PVC. Yes, the table does not quite show the max, since there is no zero ft depth column, but the pressure is still going to be well under 160.

    I agree with them that it should have a flow inducer, which is what I think they are calling a cooling jacket.

    Now can this provide 50 psi at 7 gpm into the house? Looking at the graph, the head is less than 300 ft at 0 gpm at the pump.


    img_3.png IMG_4.png
     
    Last edited: Jan 28, 2020
  11. valveman

    valveman Cary Austin Staff Member

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    Pump Controls Technician
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    Well I am glad they know and use Cycle Stop Valves, but sounds like they could use a little more instruction. Like Reach has shown, that pump can only build 290' or 125 PSI max, and sch 120 pipe is good to 300 PSI. Pipe is not going to be a problem. With 6" casing there is no reason a 4.5" or 5" flow inducer cannot be used and should be used with or without a CSV. If the pump is set above the perforations it really doesn't need a flow inducer at all. Now there is really no reason to set that pump any deeper than about 170', as 120' is as deep as it will go and still produce 50 GPM at 50 PSI. It doesn't matter how deep a pump is set, it is still only lifting from the water level. If the pumping level is any deeper than 120' you will need a different/larger pump to get 50 GPM at 50 PSI.
     
  12. jed1154

    jed1154 Member

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    Feb 11, 2008
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    Based on my well log for this well, the fluid level is at 222'. Pump is set at 360'.

    So....where does this leave us?
     
  13. valveman

    valveman Cary Austin Staff Member

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    Needing more than 5 horses to get 50 GPM at 50 PSI. Again just picking 300' as the pumping level from the info you gave, it would take 7.5HP to make 50 GPM. Do you really need 50 GPM? That would handle a fairly large cattle operation. 50 GPM is 72,000 gallons per day.

    Even this pump only makes 225 PSI max pressure for the pipe at the bottom. The back pressure at the CSV would be 128 PSI with a water level of 222'. With the CSV at 55 and using a 40/60 switch, that would make for differential pressure through the CSV of 69 PSI. From the chart above that would be about 7.9 GPM minimum flow through a CSV3B2T. This is how the CSV automatically gives additional flow to cool the larger, higher pressure pumps. This pump has 18 impellers and can use a little more than 5 GPM cooling, so the CSV gives it 7.9 minimum.

    45S75-18 jpeg.jpg
     
  14. jed1154

    jed1154 Member

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    I don't need 50GPM at 50PSI. The 50GPM will be accomplished the same way it is now...just open the valve on the tee to the pond. Forget the pond. Im only interested in the CSV for the residential supply to the home.
     
  15. valveman

    valveman Cary Austin Staff Member

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    You don't need a 5HP for residential stuff. But to be able to open a valve and pump 50 GPM to the pond as well as residential stuff a larger pump is needed. Here is the 5HP I would use. It will only pump about 45 GPM running wide open to the pond, and will do 35 GPM at 50 PSI from 300'.
    35S50-19 jpep.jpg
     
  16. Reach4

    Reach4 Well-Known Member

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    Location:
    IL
    He is asking if/how he can feed the house directly without pulling the existing pump, and without an atmospheric tank for the house, but maybe somehow restricting pond-filling while the house is using water.

    I would think that knowing the deadhead pressure at the surface would be important to know if there is even a possibility of that.
     
  17. valveman

    valveman Cary Austin Staff Member

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    Pump Controls Technician
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    That 60S50-9 can pump 50 GPM from 222' running wide open to a pond. But if the water level is really at 222', that pump can only build 29 PSI, so it can't work with a pressure switch and supply water to the house at any flow rate. You could fill a storage tank with the 5HP well pump and use a 3/4HP and a PK1A to pump from a storage tank to the house with 40/60 pressure switch and 50 PSI constant from the CSV.
    LOW YIELD WELL_ CENTRIFUGAL_PK1A.jpg
     
  18. jed1154

    jed1154 Member

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    OK. This is where we are headed it looks like. I can't believe the well guy wouldn't have mentioned that we can't use this on a pressure tank at 40/60.

    So....here we are.

    WHat CSV do I need for the 1 or 1.5HP pump that is in my cistern pumping back to my pressure tank? The pump is sitting in 20 feet of water I think.
     
    Last edited: Jan 29, 2020
  19. valveman

    valveman Cary Austin Staff Member

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    If you already have a pressure tank and pressure switch, all you need is the CSV1A. If you need a tank, switch, CSV1A, and everything needed the PK1A kit has all of that.
     
  20. jed1154

    jed1154 Member

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    Feb 11, 2008
    Location:
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    OK. Looks like the cheapest option here (which is not cheap) is to seal up our cistern and utilize that. We will fill the cistern at 50GPM. It holds about 7,500 gallons and contains a submersible well pump and float switches. Sealing is expensive, but its half the cost of a poly tank that holds 1/3 as much water. Might as well make use of the cistern and get it to stop leaking. Then we can put in the CSV1A on the small well pump and have a more reasonably set up system.
     
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