Customer Solutions

RIO Modules and NI LabVIEW Automate Irrigation Spray Testing

Author(s):

Charles W. Kincade, CK Consulting; Patrick Crais, Hunter Industries; Jeff Smith, Hunter Industries

Industry:

Water/Wastewater

Product:

LabVIEW, LabVIEW FPGA, PXI/CompactPCI

The Challenge:

Automating irrigation spray nozzle testing to improve accuracy, eliminate environmental effects, and speed the design, analysis, and testing throughput.

The Solution:

Using National Instruments Reconfigurable Input/Output (RIO) systems to provide the high-speed, large quantity data acquisition capability to measure spray precipitation in real-time.

Intensity Graph Display Shows Real-Time Spray Pattern

Designing, Testing, and Fabricating Sprinkler Designs

Hunter Industries needs the ability to design, fabricate, and test the sprinkler designs in an accurate, timely, and cost-effective manner. The NI RIO systems provided the hardware impetus for Hunter’s Test Department to build a 40 ft by 20 ft indoor spray test facility that solved the testing shortcomings.

CK Consulting developed the software to control the water flow and acquire and display precipitation data from 714 rain gauges in real time. This integrated spray test system gives the designers feedback within minutes.

In the highly competitive commercial and residential irrigation market, Hunter Industries must constantly improve the performance of its irrigation products. As a part of the process to bring newer and better products to market, Hunter must balance the ease of installing spray nozzles with precision fabrication to ensure that the entire area receives the intended amount of water. Product testing gives the design engineers confidence that the designs perform to their specifications.

A number of factors influence the validity of a test, including:

• Environmental – wind, relative humidity, air temperature
• Water flow – water pressure, flow rate, water temperature
• Testing timeliness
• Measurement accuracy

The nozzle spray pattern dimensions resulted in many test facilities being located in a large outdoor field. Measurement collectors, called “catchments,” ranged from self-tipping rain buckets to calibrated beakers or cups. California State University at Fresno’s Center for Irrigation Technology (CIT) in the rich San Joaquin Valley operates an indoor measurement facility to test new and redesigned spray nozzles. A test procedure consists of mounting the test nozzle in the test fixture and measuring the volume of water collected in a spatially distributed array of calibrated beakers. After each test, the test technician records the amount of water in each of the beakers and manually enters the data into a database. Several runs could be performed and the data compared for consistency. The most significant disadvantage was the timeliness of the data since the nozzles had to be shipped to and from the facility. A standard nozzle test costs approximately $200.

Approach

Hunter made the decision to build a spray test facility at their plant in San Marcos, CA, to address all of the factors affecting the validity of nozzle testing. They selected a large indoor room that would house a 20ft radius semicircular test fixture. The room was fitted with HVAC to maintain a temperature and relative humidity and eliminate wind effects. Water service was added with an electrically actuated control valve, an electrically selectable pressure regulator and a water pump.

The geometry, with catchments mounted at 1ft. grid intervals over the fixture, resulted in more than 700 catchments – a daunting data acquisition problem. Rain gauges were available with digital readouts at the gauge base; others sent data via serial communications; others were tip-type that collected a set amount of water and then tipped to trigger a pulse counter; others counted water drops. Whatever the type, the sheer number of catchments, 714 in particular, was a data acquisition nightmare.

Heath Noxon, the NI District Sales Manager for North San Diego County, provided the solution using the PXI-7831R reconfigurable I/O FPGA module that offered full, eight channels of analog input, eight channels of analog output, and 96 digital lines. With loop rates of up to 40 MHz, the system was fast enough to actually count the pulses as water drops passed through the rain gauges, and only eight boards could acquire data from all 714 rain gauges.

A proof-of-concept demonstration system proved the feasibility. At that time, NI annoucemed the new PXI-7811R Reconfigurable I/O FPGA module that offered 160 digital lines. With four of the new modules and one PXI-7831R Reconfigurable I/O module, the entire test facility can be monitored and controlled. An eight-slot PXI Chassis uses an NI MXI-4 serial link to interface with the PC-based data analysis and display system.

Analysis and Control Software

CK Consulting developed the integrated data analysis and control software in NI LabVIEW 7.1 and LabVIEW FPGA module. Software was created in the following four major functional modules:

• Main display and control screen – provides a real-time display of test results
• Database management functions – maintains the nozzle parameters of flow rate, water pressure, and radius of throw specification values
• Report generation functions – provides capability to create standardized test reports and to create data files in the Center for Irrigation Technology format
• FPGA data acquisition and control functions – consists of the FPGA-based data acquisition drop counter algorithm and the control functions to control the valve, pump, and pressure regulator

The main display and control screen provides the test engineer with real-time test results in four different representations.

1. Radius of Throw – displays the spray pattern as a constant precipitation rate over the catchment grid in real time
2. Intensity Graph – displays the real-time spray pattern in a color intensity format
3. Map Counter – display is a matrix of numeric indicators representing the catchment layout and displays, in real time, the actual drip count data
4. Catchment Grid – display is a matrix of LED indicators representing the catchment layout and displays, in real time, when a catchments record drops.

NI Hardware and Software Improves Test Process

With the help of NI hardware and software, Hunter Industries has created a test fixture that gives their design engineers an important tool for improving the irrigation spray nozzle design, fabricate, and test process. Design engineers can now test new nozzle designs in a matter of minutes.

For more information, contact:

Charles W. Kincade

Software Engineer

CK Consulting

17855 Saint Andrews Dr.

Poway, CA 92064

Tel: (858) 592-0789

Fax: (858) 487-3572

E-mail: ckincade@san.rr.com