Irrigation in the Pacific Northwest

Hand Move Sprinklers

Use this form to calculate recommended set times, nozzle diameters, pipe sizes, and lateral pressure losses for hand move sprinklers.

Learn more about the units used on this page.

 

Net Depth, Suggested Move Interval, and Suggested Nozzle Diameter

A soil's water holding capacity is the difference between field capacity and wilting point. For more information about a particular area, check the Columbia Basin Soil Survey or get suggested capacities by soil or by crop type.

The maximum net depth of water per irrigation is defined by how much water a soil can hold without losing it to leaching. If the soil is full of water, the crop can use this much water before it is stressed. The move interval assumes a maximum set time on only 12 hour intervals because it is less work. A good estimate for a set-move sprinkler ranges from 50 - 75%. The suggested nozzle diameter assumes that the nozzles are in good condition, and are all the same (replacement nozzles are typically less than $1 per nozzle).

Soil's Water Holding Capacity:
in/feet
Rooting Depth:
Management Allowable Deficit:
%
Maximum ET:
Number of Sets Per Line:
Time Required to Move to Next Set:
Line Spacing:
Sprinkler Spacing:
Irrigation Efficiency:
%
Operating Pressure:
Maximum Net Depth of Water Per Irrigation:
Calculated Maximum Move Interval:
hrs between sets
Suggested Move Interval:
hrs between sets
More lines needed to be practical and avoid significant crop stress.
Suggested Nozzle Diameter:

 

Suggested Pipe Size


This is based on a maximum water velocity of 5 feet/second in the pipe. You can get away with smaller pipe sizes (i.e. faster velocities) if you are very careful to avoid water hammer by shutting valves slowly, putting in pressure relief valves, and trying to avoid the water hitting the end of a closed pipe at high speeds. Use negative for downhill from water source, positive for uphill from the water source.

 

Maximum Number of Heads Per Line:
sprinkler heads
Pipe Size:
in

 

Pipeline Pressure Differences


This calculator uses the suggested pipe size and assumes the use of aluminum pipe with couplers. If 1" pipe is used then losses will be much higher. The elevation difference value can be a negative or positive value, but cannot be set as zero. If the area is downhill from the water source, use a negative elevation difference, otherwise use a positive value if uphill from the water source.

Negative results = pressure drop. Positive results = pressure higher at end than at mainline.

 

Top to Bottom Field Elevation Difference:
Estimated Pressure Difference:

 

 

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