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Thread: VS Pump Flow Issue

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    Join Date
    Jan 2013
    Location
    Australia
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    12

    VS Pump Flow Issue

    Hi All

    I have a Viron P320 VS pump and Viron EQ SWG on a small 18000 litre pool. A year ago I redid the suction line from 40mm to 50mm (rest is all 40mm) and installed a Flow Vis check valve (measures flow also) on the discharge line going into 25 inch sand filter (in 50mm pipe).

    I used the flow Vis to ascertain at what minimum flow I needed to clear the salt cell of gas build up (a known issue with Viron pump when trying to run on low) as manufacturer states min 120 lpm required. I have set the pump on medium speed and tuned the rpm to 2100 (increase of 300 rpm from default) and the flow vis reads roughly 120 lpm for 50mm pipe scale and the cell does indeed stay clear of gas build up so all good.

    I was thumbing through my pool equipment manuals the other day and found a pump curve graph for the different default speeds of the Viron. On the chart it states that low should do 121 lpm, med 212 and hi 252 (my sand filter booklet states that 176 is min backwash flow required).

    I know that piping size, bends, distance, layout...etc... will all affect the resistance that the pump must push the water through but it seems I am way off the mark from what the vendor states to what the equipment is capable of in my system. I am now concerned that the backwashing may be ineffective as at priming rpm the pump only achieves 160 lpm according to the Flow Vis.

    I guess this leaves me with the following paths:

    1. I have a problem with my system (piping,pumping, filtering)

    2. The vendors specs are fanciful Baloney Sandwich and this is all this pump can do in real life

    3. Vendors specs are correct but there is no problem as you really can lose this much flow

    Help please.
    Fibreglass 18000L pool, Viron P320 pump, Davey 25" sand filter, Viron EQ25 SWG with ORP and Acid dosing.

  2. Back To Top    #2
    mas985's Avatar
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    May 2007
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    Pleasanton, CA
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    Re: VS Pump Flow Issue

    The flow you get all depends on the head loss of plumbing and equipment so each pool will be different. In order for the manufacture to quote flow rates, then had to assume a specific plumbing setup. In that table, I looked on their web site, it shows head loss too. Based upon the table, it looks as though they are using plumbing Curve-C as a baseline which is reasonable for 2" plumbing. So my guess is that your setup just has much more head loss than what they have in their table so you would get much lower flow rates.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

  3. Back To Top    #3

    Join Date
    Jan 2013
    Location
    Australia
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    12

    Re: VS Pump Flow Issue

    Is there a plumbing curve that would apply for 1.5" pipe, would be interested to see the difference.
    Fibreglass 18000L pool, Viron P320 pump, Davey 25" sand filter, Viron EQ25 SWG with ORP and Acid dosing.

  4. Back To Top    #4
    mas985's Avatar
    Join Date
    May 2007
    Location
    Pleasanton, CA
    Posts
    11,473

    Re: VS Pump Flow Issue

    Yes, there is a plumbing curve for 1.5" plumbing but I don't think that is what you are asking. I think you are asking what the performance of the pump would be for plumbing Curve-A (1.5" plumbing) and that would need to come from the manufacture.

    This brochure has the head curve for the pump: http://www.astralpool.com.au/sites/d...0600_web_2.pdf

    The plumbing curves in US units are as follows:

    Plumbing Curve C (~2" plumbing) Head Loss (feet) = 0.0082*GPM^2

    Plumbing Curve A (~1.5" plumbing) Head Loss (feet) = 0.0167*GPM^2

    Plumbing Curve B (~1.25" plumbing) Head Loss (feet) = 0.05*GPM^2

    If you convert the units and plot it over the head curve in the brochure, where the plumbing curve intersects the head curve is the operating point.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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