At the Pump
Flow and pressure at the pump are recorded for each block that is being tested.
The flow can be recorded in litres per second (L/s), litres per minute (L/min), or cubic metres per hour (m3/h) at the pump outlet using an ultrasonic flow meter. To obtain an accurate reading the flow meter needs to be set up on a straight section of the pump outlet pipe that is some distance away from valves, elbows and filters to minimise turbulence. This measurement can be compared with readings on the controller and timed runs on the water meter.
The flow meter also records velocity and this is used to check that the mainline is operating within specification. Pressure is recorded from the installed pressure gauge or from the controller. There should always be a functioning pressure gauge at the pump or controller. Readings are taken separately for each block that is being tested. The pump specifications can generally be obtained from the compliance plate if the grower is unable to supply them.
Pump type, model, inlet outlet impeller ratio, motor model and revolutions per minute (rpm) details are required to check the pump efficiency and ensure that it is correctly matched to the irrigation setup. Other information needed includes inlet and outlet pipe size to and from the pump, water level above or below the inlet pipe, and the length of the inlet pipe. The pump or bore location is marked with the GPS device. A photograph of the pump and piping/filter arrangement is taken for reference.
During the test run for the selected block we need to know if water is flowing to any other points, such as tanks or dams. It is important to account for all of the water flow from the pump so that any significant differences in the flow between the pump and the block can be explained. Any visible leaks between the pump and the block which may account for some of these differences are noted.
Assessment results
On completion of the assessment, DAFWA staff will provide each grower with a report with an analysis of the results. This enables growers to benchmark their irrigation against the high performing businesses in their industry and identify priorities to help improve the return to their businesses per megalitre of water used in their farming operations. Contact Tilwin Westrup if you would like to be involved.