Is there an equation to how much the head pressure is reducing the flow rate by (GPH)?

[Papu]

Hi ! Supposedly, this is the way to find out what the head pressure is?

Every 1 ft of vertical rise = 1 ft of head pressure
Every 90° elbow fitting = 1 ft of head pressure
Every 45° elbow fitting = 0.5 ft of head pressure
Every 10ft of flat horizontal distance = 1 ft of head pressure

Question is.. say if I know my head pressure total is "6 ft" for example and my flow rate on the return pump is 1600gph. Is there an equation/formula to figure out an estimate on how much is being reduced? On BRS's guide.. they estimated one of the 1600gph would run an estimate of 700gph with a 5.6 head pressure, but don't explain on how they got the 700gph.. it's just a chart showing the curve... but that curve may look different if the head pressure height is different or the pump is weaker/stronger.

Most would just tell me.. as long the head pressure is less than what most manufacturer's return pump max head would be. (example: if ecotech vectra states less than 11 ft)
But.. that still doesn't let us know if we're running at 5x or 8x turnover etc.

 

[DDenny]

Here is a calculator to give you an idea

Pond Supplies, Pond Liner & Water Garden Supplies - Head Pressure Calculator

Head Pressure Calculator

www.pondliner.com

Edit it just gives you head pressure but the manufacturers usually will supply a chart with the calculated head pressure and estimate flow rate at the head pressure. The other site Reef central used to have a calculator if I remember correctly.

 

[FUNGI]

try this:

Pump Calculator | Pentair AES

Pentair is dedicated to excellence in all aspects of our business. Whether you need system design, technical service or unrivaled equipment-you can count on us.

pentairaes.com

 

[KrisReef]

Hi ! Supposedly, this is the way to find out what the head pressure is?

Every 1 ft of vertical rise = 1 ft of head pressure
Every 90° elbow fitting = 1 ft of head pressure
Every 45° elbow fitting = 0.5 ft of head pressure
Every 10ft of flat horizontal distance = 1 ft of head pressure

Question is.. say if I know my head pressure total is "6 ft" for example and my flow rate on the return pump is 1600gph. Is there an equation/formula to figure out an estimate on how much is being reduced? On BRS's guide.. they estimated one of the 1600gph would run an estimate of 700gph with a 5.6 head pressure, but don't explain on how they got the 700gph.. it's just a chart showing the curve... but that curve may look different if the head pressure height is different or the pump is weaker/stronger.

Most would just tell me.. as long the head pressure is less than what most manufacturer's return pump max head would be. (example: if ecotech vectra states less than 11 ft)
But.. that still doesn't let us know if we're running at 5x or 8x turnover etc.

Those charts showing the output of the pump at each head pressures are likely measurements from tests they run on that pump. The chart is there to ESTIMATE output at that given head pressure. There estimates don't include bends in the hard pipe, just output at that vertical lift.

If you need to know exactly what you are getting you need to buy the pump (or pumps) and run them on your system and measure the output with a bucket test and then you will know.

 

[Papu]

Thank you ! I used the calculator and then chatgpt converted the rest of the psi loss into gph for me xD

 

[Papu]

Those charts showing the output of the pump at each head pressures are likely measurements from tests they run on that pump. The chart is there to ESTIMATE output at that given head pressure. There estimates don't include bends in the hard pipe, just output at that vertical lift.

If you need to know exactly what you are getting you need to buy the pump (or pumps) and run them on your system and measure the output with a bucket test and then you will know.

Yeah.. for sure.. don't need to know exactly.. but just a rough estimate close enough. Good to know! I will do that if I'm looking for full accuracy. Ty. I think most reef just need 5x-10x correct? I assume if the manufacturers are saying as long the head pressure is less than their recommended max head.. it's gonna sit lowest at 5x turnover correct? (assuming say if the head pressure is very high and close to their max head recommendation)

 

[KStatefan]

Hi ! Supposedly, this is the way to find out what the head pressure is?

Every 1 ft of vertical rise = 1 ft of head pressure
Every 90° elbow fitting = 1 ft of head pressure
Every 45° elbow fitting = 0.5 ft of head pressure
Every 10ft of flat horizontal distance = 1 ft of head pressure

The first one is the only one that is correct.

The other three are friction loss and will change depending on flow and material of the pipe.

I like the Pentair calculator that was posted above to get close.

If you want to learn more about the calculation search Equivalent Length Method. That is what most of the calculators are based on. The other site used to have a calculator that had the pump curves in it for most common pumps at the time but I do not think it is still up any where.

 

[KrisReef]

The newer DC pumps are adjustable and combined with their published head pressure output curves you can grab one that is close to what you need and adjust it up or down to run on your set up. The old days we bought pumps and ran them at one speed with valves to choke them back if they were too strong.

 

[Papu]

Good to know, thanks guys !