Updated Publication for Calibration of Stationary and Traveling Systems

By: Emily Herring- Livestock Agent –Pender County, Publication courtesy of NCSU, AG-553-09 and Amanda Hatcher, Duplin County Livestock Agent

North Carolina State University has released an updated version of “Calibration and Uniformity Assessment for Animal Wastewater Application Equipment” to give updated information on hard hose travelers and solid set systems.  Irrigation systems wear and develop buildup, therefore affects their performance, both from an irrigation standpoint and from an economic standpoint.  Calibrations are required once every two years for swine facilities in North Carolina with a state general permit and required once a year for swine facilities with an NPDES permit.

Here’s a summary of things to keep in mind before starting a calibration:

·      A manufacturer’s chart for your system’s sprinkler and nozzle combination is needed for your irrigation design or wetted acreage determination.

·      Perform calibrations during periods of no to very light wind (less than 5 mph).

·      Check wetted diameter and flow pressure under periods of normal pressure.

Equipment needed to complete a calibration:

1.     Pressure gauge, either a mounted gauge or a handheld with pitot tube. (Which will cost roughly $38.00 offline.)

2.     Flow meter with in-line adapters IF field-measured nozzle pressure and manufacture’s charts will not be used to obtain flow rate.

3.     Measuring tape, 200-300 feet or wheel. (A measuring tape will cost roughly $25 offline.)

4.     Flags for checking wetted diameter. (Roughly $5 for a set of flags.)

5.     Caliper for measuring nozzle size. (Roughly costs $10.)

6.     Calibration forms for recording measurements.  These can be found at your local Extension Office.

For hard-hose travelers and stationary systems (solid sets), the following steps are needed:

1.     Measure the nozzle size of traveler guns.

2.     Measure pressure at the nozzle or sprinkler.

3.     Measure the wetted diameter of the nozzle or sprinkler.

4.     Measure the flow rate.

5.     Compare the measured pressure, wetted diameter, and flow rate against the manufacturer’s chart, irrigation design documents, and/or the wetted acreage determination.

Although the rain gauge method that was once needed every three years is not required now to determine uniformity, sprinkler spacing (or lane spacing for travelers) must be within design specifications and pressure must be within the ranges provided by manufacturer (Liu, 2009; 9^th SB 1217 Guidance Document, North Carolina 1217 Interagency Group, 2009).  To check for uniformity:

1.     Compare field-measured wetted diameter and pressure to manufacturer’s charts.

2.     Calculate the sprinkle or lane spacing as a percentage of field-measured wetted diameter to determine if spacing falls in the recommended range.

Field data sheets at the end of the publication help calibrations to go more smoothly.  If you would like to receive a copy of this publication contact or if you have any questions about calibrations, contact your County Extension Agent.  For a total estimated onetime cost of the equipment needed to do a calibration at the most roughly being $78 it would be a good way to save money on the farm versus paying a company to do it.