Maintenance, 4 calibration table – Vaisala HMP140 User Manual
Page 15
HMP140A SERIES
U175en-1.5
Operating Manual
1999-12-08
11
4.4
Calibration table
Temperature
°C
15
20
25
30
35
°F
59
68
77
86
95
LiCl
%RH
*)
11.3
11.3
11.3
11.3
4...20 mA
mA
5.81
5.81
5.81
5.81
0...20 mA
mA
2.26
2.26
2.26
2.26
0...1 V
V
0.113
0.113
0.113
0.113
0...5 V
V
0.565
0.565
0.565
0.565
0...10 V
V
1.13
1.13
1.13
1.13
NaCl
%RH
75.6
75.5
75.3
75.1
74.9
4...20 mA
mA
16.10
16.08
16.05
16.02
15.98
0...20 mA
mA
15.12
15.10
15.06
15.02
14.98
0...1 V
V
0.756
0.755
0.753
0.751
0.749
0...5 V
V
3.780
3.775
3.765
3.755
3.745
0...10 V
V
7.56
7.55
7.53
7.51
7.49
*)
LiCl solution must not be used or stored in temperatures below +18
°
C (+64
°
F);
otherwise the equilibrium humidity of the salt solution changes permanently
Table 1
Greenspan’s calibration table with output values according to
the chosen scale
5.
MAINTENANCE
5.1
Replacing the HUMICAP
180 sensor and the filter
Remove the damaged sensor and insert a new one. Handle the sensor by the
plastic socket. DO NOT TOUCH THE SENSOR PLATE. Check the output
after sensor change. If it deviates too much from the reference value,
recalibrate the transmitter. Note that even after sensor change, the accuracy is
still +7 %RH.
Replace a dirty filter to ensure a maximum lifetime for the sensor. Do not try
to clean the filter. The sensor can be cleaned with distilled water; if this does
not help, replace the sensor. Do not use any mechanical methods.