Select the Appropriate Pumps and Controls Understanding Basic

Select the Appropriate Pumps and Controls

Understanding Basic Pump Selection Considerations • Matching the pump and system • Flat vs. steep curves © Irrigation Association

Water Horse power where: WP = water power output, hp H = total operating head, ft Qs = design discharge of the irrigation system, gpm © Irrigation Association

Brake horse power where: BP = power input required by the pump, hp Ep = the pump efficiency, %. © Irrigation Association

Total power input where: KW = Ep = Em = pumping plant power input, kw the pump efficiency, %. the motor efficiency, %. © Irrigation Association

Total Dynamic Head (TDH) is the energy that the pump imparts to the water for a specific flow rate (measured in feet) • H p • H s • H e • H f • H m = pressure at outlet of discharge pipeline = lift (+) or head (-) from water surface to pump = lift (+) or fall (-) from pump to outlet of discharge pipeline = friction loss in discharge pipeline = miscellaneous losses (e. g. , valves, reducers, etc. )

$Practice example The GIR requirement is 1 inch per 3 days and the fraction$

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. © Irrigation Association

Let’s Go to Our Manuals and See What We Can Learn © Irrigation Association

Steep v. s. flat © Irrigation Association

System curves © Irrigation Association

System Curves © Irrigation Association

Big Nozzle approach where: Qs = Ks = TDH E = design system discharge, gpm system discharge coefficient = total dynamic head (system head), ft total elevation change in the system, ft © Irrigation Association

Understand Types of Electronic Controls Available • System protection and shut down • Automated controls • Remote controls © Irrigation Association

Integrate Pump and Pivot Controls © Irrigation Association

Inside the Alignment Box © Irrigation Association

Chemical Injection Equipment © Irrigation Association

Electronic Controls © Irrigation Association

Computer Management © Irrigation Association

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