Campbell Scientific 223-L Delmhorst Cylindrical Soil Moisture Block - Manual (Page 19)

223 Delmhorst Cylindrical Soil Moisture Block
Typical Values from TABLE 7-3
Block Resistance (kohms)
FIGURE 7-2. Polynomial fit to typical block resistance vs. water
potential
TABLE 7-4. Polynomial Coefficients for Converting Sensor Resistance to Bars
BARS = C
0
+ C
1
(R
s
) + C
2
(R
s
) 2 + C
3
(R
s
) 3 + C
4
(R
s
) 4 + C
5
(R
s
) 5
(BARS) MULT. (R
1
) C
0
C
1
C
2
C
3
C
4
C
5
0.1–10 0.1 0.15836 6.1445 –8.4189 9.2493 –3.1685 0.33392
TABLE 7-5. Polynomial Error – 10 Bar Range
BARS
V
s
/V
x
R
s
(kohms × 0.1)
BARS
COMPUTED
ERROR
0.1 0.0566 0.006 0.1949 0.0949
0.2 0.115 0.013 0.2368 0.0368
0.3 0.2063 0.026 0.3126 0.0126
0.4 0.2701 0.037 0.3746 –0.0254
0.5 0.3506 0.054 0.4670 –0.0330
0.6 0.4286 0.075 0.5756 –0.0244
0.7 0.4624 0.086 0.6302 –0.0698
0.8 0.5238 0.11 0.7442 –0.0558
0.9 0.5833 0.14 0.8778 –0.0222
1.0 0.6296 0.17 1.0025 0.0025
1.5 0.7727 0.34 1.5970 0.0970
1.8 0.8000 0.40 1.7834 –0.0166
2 0.8333 0.50 2.0945 0.0945
3 0.8780 0.72 2.8834 –0.1166
6 0.9259 1.25 6.0329 0.0329
10 0.9444 1.70 9.9928 –0.0072
ERROR (BARS) = TABLE 7-3 VALUES – COMPUTED VALUES
13