Operation
10
CALIBRATION CONSIDERATION / LIMITS
Typically the moisture tester will be consistent
with most elevator testers over a broad range of
moisture levels. However, there are some things
to consider when thinking about your moisture
tester calibration.
NOTE: Graph provided is for illustration
purposes only and does not reflect
actual test data.
Tester Differences:
Your moisture tester unit,
may not match a given elevator tester. None of
the testers exactly match the actual weighted
moisture of any given grain. There is no national standard for elevator testers. The
difference between moisture testers and various U.S.D.A. approved elevator testers
is not a constant value. A correction at one moisture level may not be valid for a
different moisture level. Graph 1 shows how the moisture tester might compare to
an elevator tester over a broad range of moisture levels. The moisture tester, and
most elevator testers (shown in graph by solid line) will closely match those of the
moisture tester (shown by dashed line) for that range, as illustrated. However, as we
get away from mid-range into the high and low moisture levels, differences between
elevator tester and moisture tester not only become greater, but may switch from a
moisture tester reading higher than elevator tester to a reading lower than the eleva-
tor tester. For example, in Graph 1, the area between B and C represents the mid-
range moisture. Moisture tester readings match elevator tester readings in this area
with an accuracy of plus or minus 0.5 percent. The area between A and B represents
the low moisture range. Moisture tester readings differ more from elevator tester
readings, and are LOWER than elevator tester readings. The area beween C and D
represents the high moisture range. Moisture tester readings again differ more from
elevator tester readings than they did at mid-range moistures, but now the readings
are HIGHER than elevator tester readings.
Calibration Requirements:
Graph 1 illustrates that moisture tester readings closely
match elevator tester readings for mid-range moisture levels.
(Graph is for illus-
tration purposes only and does not reflect actual test data.)
Calibration changes
required for grain in this moisture range will be small, if any. However, if grain is very
dry (Low Moisture Range) or very wet (High Moisture Range), it may be necessary
to calibrate your moisture tester unit against the elevator tester using a sample of
your grain in both testers. Record the calibration correction required. It will be valid
for all testing in that moisture range for that grain.
