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Thread: Finding the flow curve

  1. #1
    Senior Member Puffin's Avatar
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    Finding the flow curve

    Hey guys, I'm trying to figure out what the flow curves are on the pump I have.

    There is a metal decal on the impeller housing that reads:
    Model Number: P2RA5E-124L
    Code number: IL89S
    STARITE INDUSTRIES.

    I can't seem to find information on this particular pump. Apparently its been replaced with a new model.

    Any help would be great.
    19,600 gal, Vinyl, Grecian L, StaRite Dura-Glas 1 HP pump, 3/4hp booster, Pentair Clean and Clear 420 Cartridge filter
    The Pool Cleaner 4x, PoolSkim

  2. #2
    Administrator JasonLion's Avatar
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    Re: Finding the flow curve

    That is a StaRite Dura-Glas 1 HP up-rated pump. I believe that is curve C on the graph on page 2 of this brochure.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    TFP Admin. Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

  3. #3
    Senior Member Puffin's Avatar
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    Re: Finding the flow curve

    Thank you. I guess I need to calculate the actual head of my pool, so I can get an accurate flow rate.

    My filter clean is 15psi using that formula from the hydraulics page. It gives me 37.65 on the return side.

    For the suction side, I'll go and get a vacuum gauge after work. I do have a question about that. The drain plug look like its maybe 1/2" Do the vacuum gauges have a 1/2" threaded ends? I just want to make sure I buy what I need so I can do this right.
    19,600 gal, Vinyl, Grecian L, StaRite Dura-Glas 1 HP pump, 3/4hp booster, Pentair Clean and Clear 420 Cartridge filter
    The Pool Cleaner 4x, PoolSkim

  4. #4
    Senior Member mas985's Avatar
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    Re: Finding the flow curve

    Why do you need accurate flow rate?
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study
    18'x36' 20k gallon plaster/gunite pool, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge Filter, 450 sq-ft EPDM Solar Panel, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater, ThePoolCleaner, DIY Acid Dosing

  5. #5
    Senior Member Puffin's Avatar
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    Re: Finding the flow curve

    There was an assertion that my equipment (filter and pump) are mismatched. Because the flow rate of the pump exceeds the maximum flow rate of the filter. When I attempted to discuss this point, I realized I don't have enough information about my system to be able to do that intelligently. The pool person was making assumptions (system head, and in turn pump flow rate, etc...) but since I didn't have anything more specific, I couldn't really argue.

    I tried finding the flow curve on my own, but was having trouble. You folks here are very knowledgeable, I figured someone could point me in the right direction. As I understand it, I need to know my total head, so I can find the actual flow rate the pump is producing. Then I verify that things are within range. Also, I guess there is a bit of curiosity as well.

    A side question. Does the filter need to be clean to get an accurate reading on the suction side?
    19,600 gal, Vinyl, Grecian L, StaRite Dura-Glas 1 HP pump, 3/4hp booster, Pentair Clean and Clear 420 Cartridge filter
    The Pool Cleaner 4x, PoolSkim

  6. #6
    Senior Member mas985's Avatar
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    Re: Finding the flow curve

    Yes, the return side plumbing head affects flow rate which in turn affects suction head. But I suspect the flow rate will be more than the recommended 62 GPM unless there is a lot of suction head (> 15').

    A simple fix is an impeller swap.
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study
    18'x36' 20k gallon plaster/gunite pool, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge Filter, 450 sq-ft EPDM Solar Panel, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater, ThePoolCleaner, DIY Acid Dosing

  7. #7
    Senior Member Puffin's Avatar
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    Re: Finding the flow curve

    *sigh*
    Well, I appreciate your advice and expertise. I'll still check and confirm it. At least then I'll know.

    To to fix this I can, replace the impeller, pump or filter?
    19,600 gal, Vinyl, Grecian L, StaRite Dura-Glas 1 HP pump, 3/4hp booster, Pentair Clean and Clear 420 Cartridge filter
    The Pool Cleaner 4x, PoolSkim

  8. #8
    Senior Member mas985's Avatar
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    Re: Finding the flow curve

    Yes but obviously, the impeller would be the cheapest and most energy savings change.
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study
    18'x36' 20k gallon plaster/gunite pool, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge Filter, 450 sq-ft EPDM Solar Panel, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater, ThePoolCleaner, DIY Acid Dosing

  9. #9
    Senior Member Puffin's Avatar
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    Re: Finding the flow curve

    I'm trouble finding a vacuum gauge. The local auto parts places don't seem to have them. Even the kind that come on a break bleeder kits. I'll just order one online.

    If it hasn't been said, thank you Mark and Jason. As always, your opinions and advice are both appreciated and valued.
    19,600 gal, Vinyl, Grecian L, StaRite Dura-Glas 1 HP pump, 3/4hp booster, Pentair Clean and Clear 420 Cartridge filter
    The Pool Cleaner 4x, PoolSkim

  10. #10
    Senior Member Puffin's Avatar
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    Re: Finding the flow curve

    Not sure if I should post on this thread or start a new one. If I need to start a new one let me know or split thing one off.

    I've been wanting to replace my filter for awhile and this is kind of an excuse to do so. I don't know, something about using all that water to backwash was the filter just rubs me the wrong way. It convenient yes, but feels wasteful to me. (This is just my personal feeling, not trying to pick a fight or claim one filter is better than another.) I guess living in CA all those years rubbed off on me.

    At any rate, I'd like to get a cartridge filter. Since mismatched components was the catalyst to get me looking, I was curious if is it possible to go too big? Do they have a minimum flow rate. I was looking at some of the documentation for the Pentair and Hayward models there doesn't seem to be minimums, there is a pressure loss vs flow chart but I don't think that's the same thing.
    19,600 gal, Vinyl, Grecian L, StaRite Dura-Glas 1 HP pump, 3/4hp booster, Pentair Clean and Clear 420 Cartridge filter
    The Pool Cleaner 4x, PoolSkim

  11. #11
    Senior Member In the Industry

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    Re: Finding the flow curve

    I was curious if is it possible to go too big?
    Not with a cartridge filter. Ideally, you should determine your pump gpm and then get a filter that exceeds that gpm by at least 25%.
    Dave S.
    Site Owner 42k vinyl and concrete pool, 1.5hp pump, 140gpm filter, No SWG
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  12. #12
    Senior Member mas985's Avatar
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    Re: Finding the flow curve

    Your pool is about the same size as mine and I have a 420 sq-ft filter. I clean it once per season, usually in the spring. I prefer the cartridge filter for several reasons. First, as you pointed out, there is no back washing. Second, it has the lowest head loss of any filter so it helps the system have higher flow rates and higher efficiency. Third, if sized properly, it probably has the least amount of maintenance. And NO, they do not have minimum flow rates but neither does any other filter.
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study
    18'x36' 20k gallon plaster/gunite pool, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge Filter, 450 sq-ft EPDM Solar Panel, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater, ThePoolCleaner, DIY Acid Dosing

  13. #13
    Senior Member Puffin's Avatar
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    Re: Finding the flow curve

    Thanks again guys. That info about your filter is good to know Mark, once per season is exactly what I'm looking for. Those other reasons are good to know and a great bonuses to boot.
    19,600 gal, Vinyl, Grecian L, StaRite Dura-Glas 1 HP pump, 3/4hp booster, Pentair Clean and Clear 420 Cartridge filter
    The Pool Cleaner 4x, PoolSkim

  14. #14
    Senior Member Puffin's Avatar
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    Re: Finding the flow curve

    Oh one more question for your Mark. You say you only clear your filter about once a season. Is that using that 1-2psi rise guideline you mentioned in other posts?
    19,600 gal, Vinyl, Grecian L, StaRite Dura-Glas 1 HP pump, 3/4hp booster, Pentair Clean and Clear 420 Cartridge filter
    The Pool Cleaner 4x, PoolSkim

  15. #15
    Senior Member mas985's Avatar
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    Re: Finding the flow curve

    I don't get much of a PSI rise if any when I clean the filter but the filter is still pretty dirty. I probably could go two years between cleanings if I wanted to. Given your location, you may get a PSI rise by the time you clean the filter.
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study
    18'x36' 20k gallon plaster/gunite pool, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge Filter, 450 sq-ft EPDM Solar Panel, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater, ThePoolCleaner, DIY Acid Dosing

  16. #16
    Senior Member Puffin's Avatar
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    Re: Finding the flow curve

    *UPDATE*
    Just figured I'd give everyone an update. The new filter is installed. I got a Pentair Clean and Clear Plus 420. (The Hayward and Pentair models are so similar, it didn't seem like it mattered which I chose). At any rate, the numbers

    Clean Filter PSI 9
    Vacuum Hg 10

    Using the math from the hydraulics 101 page I get 35.09 feet of head. So that pump is producing quite a bit of GPM according to that chart (70+gpm). But the max flow rate is 150GPM and this is safely under that amount.

    One thing of note, that filter made a surprising difference in the flow in the pool. Both the returns and skimmers seem to be moving water noticeably faster than before.

    Thanks again for your help everyone.
    19,600 gal, Vinyl, Grecian L, StaRite Dura-Glas 1 HP pump, 3/4hp booster, Pentair Clean and Clear 420 Cartridge filter
    The Pool Cleaner 4x, PoolSkim

  17. #17
    Senior Member mas985's Avatar
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    Re: Finding the flow curve

    I am glad everything worked out ok and hopefully you will have long time spans between filter cleanings.
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study
    18'x36' 20k gallon plaster/gunite pool, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge Filter, 450 sq-ft EPDM Solar Panel, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater, ThePoolCleaner, DIY Acid Dosing

  18. #18
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    Re: Finding the flow curve

    I shouldn't be tagging onto an old thread at this late date, but I have the same question that Puffin asked mid-way through ( and a direct answer was not supplied ) --- Where do do find a vacuum gauge that fits the drain plug of the pump? I likewise could not find an online answer from the auto-parts stores, and the gauges at the industrial supply houses ( Grainger is the closest to my residence ) all connect with a 1/4" NPT male fitting. My drain plug measures out as 1/2" SAE with 18 NF threads. I would much prefer to make a flow-rate estimate from suction & pressure readings, than calculate it from my complex return plumbing.
    15K gallon in-ground gunite/plaster pool(58 year-old Anthony Bros.), 15'x30', depth 3-1/2'->8' . Hayward Ecostar pump. Hayward DE-3600 filter with Variflow 710XR50 1-1/2" valve. Polaris 380 cleaner & "the pool cleaner (suction)". Main-drain suction disconnected. New skimmer suction plumbing 2" PVC. Single return line 1" copper. Cleaner line 1-1/2" copper, re-plumbed in pump-house (PVC) for either suction or pressure. Hayward 3/4HP PB4 booster pump. Leslie's 260 BTU Coppertherm heater. All new suction interconnect plumbing 2". Return plumbing, filter-to-booster, 1-1/2". Single return to pool 1". All equipment located 2-1/2ft. above pool bottom level ( neg. 5ft. from surface ).

  19. #19
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    Re: Finding the flow curve

    That would be a tough adapter to find.Could you perhaps cut in a tee in your suction line close to your pump? (example of tee http://www.lascofittings.com/includes/f ... es/402.gif ) You can find these tees at Lowes,Home depot,Ace etc.. They are pretty common.
    Then just use a 1/2 X 1/4 NPT bushing,so you can install your gauge.
    Rob

    Cozumel AGP 24' 14,700 gallons
    Pentair Dynamo 1.5 hp pump
    Sta-rite Cristol-Flo II 2.3sq.ft. sand filter
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    TF-100 Testkit....$68,cheap insurance for a trouble free pool season

  20. #20
    Senior Member mas985's Avatar
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    Re: Finding the flow curve

    No need to modify your plumbing. Most automotive vacuum gauges have hoses which you can use a 1/4" hose adapter like this:



    Or you can get a vacuum gauge from eBay with a 1/4" fitting already on the gauge like this:

    http://www.ebay.com/itm/2-1-2-Inch-300- ... 564e7d7650
    Mark
    Hydraulics 101; Pump Ed 101; Pump and Pool Spreadsheets; Pump Run Time Study
    18'x36' 20k gallon plaster/gunite pool, 1/2 HP 2sp pump, Aqualogic PS8 SWCG, 420 sq-ft Cartridge Filter, 450 sq-ft EPDM Solar Panel, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater, ThePoolCleaner, DIY Acid Dosing

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