Do these calculations seem right? - LawnSite.com™

ple_1969 · #1 09-21-2011, 06:58 PM

OK, I've been going back and forth about what pump to by for an irrigation system where I'm pumping from a river. In a nutshell I'm looking to get about 35 - 40 PSI at the heads (I20 rotors). Here are some measurements:

Pull to the pump from the river - 8'
Elevation change from the pump to the highest point - 27'
Looking for 20 GPM max
Mainline will be 1 1/2" schedule 40
Valve will be 1"
Laterals will be 1 1/4" poly

Currently have the following jet pumps in mind:

F&W - CPJ15S
Goulds - HSJ15N
Goulds - J15S

Since there is about a $400 difference between the single stage and multi stage pump I want to make sure I have all my numbers correct so I can make a proper decision. A lot of my indecision has to do with PSI I can get out of each type of pump - don't now if a single stage will be have enough. But if I can use a single that $$$ in my pocket.

Below is what I'm figuring.... does this look correct?

11.7 - elevation change (27’ x .433)
3 - filter
2.28 - Mainline (200’ Schd 40 1.5”)
3 - valve
7 - laterals (20% if of head pressure)
35 - 40 - heads
TOTAL PSI LOSS = 61.98 - 66.98

Pete

Without A Drought · #2 09-21-2011, 07:07 PM

Check out watertronics.

central has recommended them, specifically the waterpak 3. its a 30gpm pump with a VFD. it comes all in an enclosure and you just need to hook up suction, electric and output.

i'm gonna use it on a similar project.

pg

ple_1969 · #3 09-21-2011, 07:17 PM

Interesting... any idea how much these go for?

Mike Leary · #4 09-21-2011, 09:38 PM

Quote:

Originally Posted by Without A Drought

Check out watertronics.

central has recommended them, specifically the waterpak 3. its a 30gpm pump with a VFD. it comes all in an enclosure and you just need to hook up suction, electric and output.

i'm gonna use it on a similar project.

pg

Link??????????