Campbell Scientific CS505 Fuel Moisture Sensor - Manual (Page 13)

Appendix A. Explanation of
Experimental Data
EXPERIMENTAL DATA ERROR DISTRIBUTION
-6
-5
-4
-3
-2
-1
0
1
2
3
4
5
6
0 10 20 30 40 5
% WATER CONTENT
(by weight)
Error % WATER
CONTENT
(by weight)
0
RMS ERROR 0.98%
RMS ERROR 1.43%
RMS ERROR 2.21%
RMS ERROR 2.37%
FIGURE A-1. Experimental Data Error-Distribution
Experiments were conducted to characterize measurement error and to
determine the calibration polynomial coefficients used to convert the output
signal to percent moisture content.
Populated circuit boards (before epoxy) oscillate with a period in the range of
0.6761 and 0.6780 milliseconds. In these experiments, three worst-case units
were chosen. Only fuel moisture sticks that pass the standard rigorous
selection criteria and then additional sorting for both oven-dry density and
sorption qualities are chosen for production. For this experiment, 36 fuel
moisture sticks were randomly selected from 300 production units. Electronic
measurements were compared to actual stick weights. The sticks were soaked
for 45 minutes, then after a five-minute dry, measured electrically and weighed
every 10 to 60 minutes until they reached 15%. Then the sticks were placed in
a 103
°C oven for further drying; more measurements were taken. At each
weigh point the sticks where rotated and measured by each of the three
electronic units. Over one thousand data points were measured for this
calibration experiment.
A-1