Figuring water line pressures, anyone know of an interactive tool?

[Brad Johnson]

We're trying to set up a pump system on the ranch and I need to figure the pressures over and above static water column for a given length of pipe. Water column is 150 ft so we already know we need 65 psi just to flow (64.95 for the pedants). There's over a half mile of pipe from well head to holding tank and we need 8 gpm at the tank. I need to know how much pressure drop we must overcome to meet that goal. Anyone know of a simple interactive tool which gives that kind of info?

If someone wants to take a stab at it...

Pipe: 1.5" Sched 40 PVC (1.490 ID)
Length: 3000 ft
Volume: 8 gpm

*Edit to add*

I found this

https://www.copely.com/tools/pressure-drop-calculator/

If I did my conversions right, it seems to indicate 7.00 psi drop using the above numbers. That's well within our existing pump's capabilities.

Brad

[Jim147]

The Engineering Toolbox might have something.

[MechAg94]

I did a google search for "water piping pressure loss calculator."  Got the links below.  Looks okay at first glance. 

You could find a Fluid Dynamics professor and get them to add it as a question on one of their tests.  You might get a correct answer in there somewhere.  They might like to hear a real world application at least.

https://www.tlv.com/global/US/calculator/water-pressure-loss-through-piping.html

http://www.pressure-drop.com/Online-Calculator/

http://irrigation.wsu.edu/Content/Calculators/General/Pipeline-Pressure-Loss.php

[Hawkmoon]

If you're just topping off a holding tank, why do you need 8 gallons per minute?

[Brad Johnson]

If you're just topping off a holding tank, why do you need 8 gallons per minute?

Usage is 2000-3000 gallons per day. The well feeds a holding tank which, in turn, feeds watering tanks.

Holding tank is a flow-through reserve. The watering tanks are normally fed via the holding tank overflow. We have the option of opening a valve at the tank base if the reserve is needed.

Brad

[charby]

I wouldn't even look at pressure, just GPM delivered to the tank.

[Brad Johnson]

I wouldn't even look at pressure, just GPM delivered to the tank.

Have to. Water line length & ID directly affect pump head numbers. It's the foundation for calculating everything else.

Good news is I got through to the pump supplier and their rule of thumb is five feet of additional head for every 1000 ft of 1.5" line. That puts us at 165' head which is right what I had calculated earlier.

Bad news is we're right at the max for their largest standard pump. Any little bit more and we'd have to go to their pro series. Nice setup but four times the price.

Brad

[K Frame]

Would it give you any benefit to go to a 2 or 3" pipe instead of 1.5"

[Brad Johnson]

Would it give you any benefit to go to a 2 or 3" pipe instead of 1.5"

At current GPM needs, no. If we needed to go any higher, yes. As it stands we should be seeing a 7 psi pressure drop from the line. Moving up to 2" wouldn't make enough change to merit the replacement cost. Fortunately we're at the limit for number of head in that group of pastures and water needs are met with the current setup. There's no anticipation of having to upgrade.

Have to give the folks at RPS Pump Systems kudos. They have been beyond helpful in getting us the info and equipment we need. The first system we purchased had everything necessary included and was essentially plug and play. If you have a solar pump need, give them a call. Ask for Danna. Tell her Brad from Lubbock, TX, and Duane from Crowell, TX, recommended her.

Brad

[Brad Johnson]

Talked to Dad over the weekend. The new setup is working perfectly. Flow is pretty much spot on the 8 GPM we needed for max-consumption days and the controller makes it dirt easy to dial back when less is needed. A single dial that sweeps from OFF to 100%.

Pump setup is the Rural Pump Service RPS800 kit. Comes with everything - pump, solar panels, and controller - and is the epitome of plug-n-play. The only thing not included is a panel mount and wiring, mostly due to customers having such varied needs. They have two- and four-panel frame kits for customers to purchase separately. Wiring is a buck a foot and RPS will pre-terminate for you at no charge. Really can't say enough good about them. They were great.

A related aside, I found out that Google Earth gives altitude data. It probably has for some time, I just didn't know about it. That little gem saved us a metric buttload of headache.

Brad