RPM vs GPM

[mactoolsix]

I have a Hayward SP3202VSP pump.
Per the Hayward online calculator my Total Dynamic Head is 37.0 feet
Pool size is 26,500
I need about 49 GPM
Where can I find a chart showing GPM vs RPM?

 

[mknauss]

Welcome to the forum!
Why do you need a certain GPM?
Can you fill out your signature?

I suggest you read ABC's of Pool Water Chemistry and consider reviewing the entire Pool School eBook.

 

[Jimrahbe]

I can't think of any reason that a pool owner needs to know the exact GPM of the pump.. Just crank up the pump speed until whatever you want to work, works like you want...

Jim R.

 

[mactoolsix]

I want to filter the 26,000 gallons once a day, but is seems waste to run the VSP at 3,400 RPM when maybe 2,200 RPM would pump enough to accomplish this in 8 or 10 hours.

 

[Jimrahbe]

M,

The idea that you have to pass your water through the filter x times a day is just a myth made up by people that don't really understand what the filter does...

Chemicals keep your pool clear and sanitized.. The filter just captures the junk that falls into your pool.

I suggest that you run at the lowest RPM that keeps your pool skimmed.. I run my VS pump at 1200 RPM, most of the time and don't care if I turn the pool water over or not..

And... if you think about it... once the first gallon of water has passed through the filter and goes back to the pool, what prevents it from going through the filter again.. The more you run the less likely that all the water is going to be run through the filter anyway..

The whole point of running a VS pump is to run slow and save on the electrical bill..

Thanks,

Jim R.

 

[MWengineer]

One reason to know flow rate is to make sure you aren't pushing more flow through your filter than it's rated for.

A quick googling provides the TDH vs flow curve at multiple speeds for that pump on the spec sheet.

TriStar VS | Pumps | In Ground Pool Pumps - Hayward Pool Products

www.hayward-pool.com

If you want to know about a specific speed, look up the pump affinity laws.

 

[mas985]

Per the Hayward online calculator my Total Dynamic Head is 37.0 feet

Very unlikely with that pump at full speed. Those online calculators are all but worthless. They usually neglect half of the plumbing contributions.

What size is your plumbing?

What is the distance between the pump and pool?

What is the filter pressure?

What kind/size filter do you have?

Given the age of the pool, my guess is 1 1/2" plumbing? Average pool with 1 1/2" plumbing would be about 64 GPM @ 68' of head on full speed. The flow rate scales with RPM (e.g. 50% speed > 50% flow rate).

But as others have mentioned, the flow rate really isn't going to be all that important unless you have a very small filter.