Manual | RIM-FVU Field Verification Unit (FVU)
Status: Final | Not confidential
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V20200309
5. Open the siphon valve. The water will flow out of the RIM-FVU to the tipping bucket rain gauge at a
predetermined rate. The number of tips can either be audibly counted or digitally counted (these can be
bought as an option), or the counts can be retrieved from a data logger and checked against calibration
specifications.
6. With an approximate volume of 653mls, the tip count should be around 101, but can vary with each
unit. Check the label for expected tip counts.
7. The Field Verification Unit comes with a 1.5mm nozzle orifice as standard for field verification. The unit
can be ordered with a 0.9mm orifice nozzle if it is necessary to perform a calibration to the Australian
Standard (AS3580.14). Drain time is around six minutes with a 1.5mm nozzle and up to twenty minutes
with the 0.9mm nozzle.
8. You will need to do the test repeated times to achieve ±2 tips counted on two progressive runs*, then
the instrument is within acceptable calibration limits. If not, then the tipping bucket limit screws will have
to be adjusted until an acceptable result is obtained after several passes
(*) Special note:
Please be aware that tip counts can vary
from tube to tube.
