Select the Appropriate Pumps and Controls. © Irrigation Association Understanding Basic Pump Selection Considerations Matching the pump and system Flat.

Select the Appropriate Pumps

and Controls

© Irrigation Association

Understanding Basic Pump Selection Considerations

• Matching the pump and system

• Flat vs. steep curves


Water Horse power

where:WP = water power output, hpH = total operating head, ftQs =design discharge of the irrigation

system, gpm


3960

QHWP s

Brake horse power

where: BP= power input required by the pump, hpEp = the pump efficiency, %.


)100/E(3960

QH

100/E

WPBP

p

s

p

Total power input

where: KW = pumping plant power input, kwEp = the pump efficiency, %. Em = the motor efficiency, %.


)100/E()100/E(5308

QH

)100/E(100/E

WP746.0KW

mp

s

mp

Hf + Hm

Hp

Q

PUMPS - HORSEPOWER DETERMINATION

He

Hs

Total Dynamic Head (TDH) is the energy that the pump imparts to the water for a specific flow rate (measured in feet)

mfesp HHHHHTDH

• Hp = pressure at outlet of discharge pipeline• Hs = lift (+) or head (-) from water surface to pump• He = lift (+) or fall (-) from pump to outlet of discharge

pipeline• Hf = friction loss in discharge pipeline• Hm = miscellaneous losses (e.g., valves, reducers, etc.)

avitySpecificGr

psiessureftHead

31.2)(Pr)(

Total Dynamic Head (TDH)

Practice example

The GIR requirement is 1 inch per 3 days and the fraction of operating time is t = 0.9. The irrigated area is 130 acres. The pumping lift (Hlift) from water surface in sump to the ground surface is 10 ft and includes the friction loss in the pump intake pipe. The pressure requirement at the pump outlet, Pout, is 79 psi.



Let’s Go to Our Manuals and See What We Can

Learn

Steep v.s. flat


System curves


System Curves


Big Nozzle approach

where:Qs= design system discharge, gpmKs = system discharge coefficientTDH = total dynamic head (system head), ftE = total elevation change in the system, ft


ETDHKQ ss


Understand Types of Electronic Controls

Available

• System protection and shut

down

• Automated controls

• Remote controls


Integrate Pump and Pivot Controls


Inside the Alignment Box


Chemical Injection Equipment


Electronic Controls


Computer Management


Computer Management

Controls

• Pressure actuated Safety switch– Loss of prime, broke pipe, loss of

fuel, etc.• Demand switches• Startup control

– Controlled startup of flow • Back flow devices• Shut off

– Pivot stuck or stopped

• Oil pressure– High or low

• Time delay limit switch• Flow switch

– No flow, high flow• Phase monitor• timers

Alarms

• High or low pressure• High or no flow• Low oil• Low pressure• Etc.

Variable speed devices

• Potentially Ideal Applications– Widely varied flow Requirements– Less total head needed as flow

requirements are dropped (Extreme friction loss or major draw-down changes in a well)

– Single Well serving a very large acreage

– Long operating hours at less than full flow – Varied crops, multiple systems on one pump

– Steep pump curves


Let’s Go to Our Manuals and See What We Can

Learn

Select the Appropriate Pumps and Controls. © Irrigation Association Understanding Basic Pump Selection Considerations Matching the pump and system Flat.

Documents

irrigation system

alignment box slide

total dynamic head tdh

pump steep pump curves

pump outlet

pump efficiency

total head

total dynamic head system