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OX-TRAN Model 2/12 R Operator's Manual
Appendix F: Preparing RH Calibration Standards
To calibrate or check the RH probes used in the OX-TRAN Model 2/12, requires RH reference values (or
standards). A RH Calibration Standard consists of a saturated salt solution or molecular sieve in a
"Calibration Flask". Calibration Standards should be kept tightly sealed using the "Flask Stopper" when not
in use. The molecular sieve should be regularly replaced.
RH Calibration Equipment
MOCON has available the following materials to facilitate the preparation of RH reference standards
suitable for the calibration of the RH Probes in the OX-TRAN Model 2/12.
Calibration Flask
•
•
RH Probe Stopper
•
Flask Stopper
Choosing a Salt Solution
Warning!
RH sensor calibration will be performed at a specific temperature. A salt must be chosen that will produce
the desired RH at that temperature.
For most salt solutions the RH produced by the solution is dependent on temperature. To choose the
correct salt solution for your application, consult one of the following resources:
Table F.1, Salt Solution Humidity Standards in Percent RH shown below.
•
Handbook of Chemistry and Physics.
•
The National Bureau of Standards.
•
Salts
Lithium Bromide
Lithium Chloride
Potassium Acetate
Magnesium Chloride
Potassium Carbonate
Potassium Iodine
Sodium Chloride
Ammonium Sulfate
Potassium Chloride
Ammonium Monophosphate
Potassium Nitrate
MOCON, Inc.
Some salts will produce exothermic or endothermic reactions when mixed
with water. Failure to use proper safety equipment when mixing salt
solution can result in frostbite or burn injuries. Salt solutions should be
prepared only by qualified people with proper safety equipment.
15 °C
6.86
11.30
23.40
33.30
43.15
70.98
75.61
81.70
85.92
93.85
95.41
Table F.1: Salt Solution Humidity Standards in Percent RH
MOCON Part Number
MOCON Part Number
MOCON Part Number
20 °C
6.61
11.31
23.11
33.07
43.16
69.90
75.47
81.34
85.11
93.32
94.62
Revision L
Calibrating the Permeant Sensor
030-802
030-803
030-804
25 °C
30 °C
6.37
6.16
11.30
11.28
22.51
21.61
32.78
32.44
43.16
43.17
68.86
67.89
75.29
75.09
80.99
80.63
84.34
83.62
92.65
92.00
93.58
92.31
35 °C
5.97
11.25
21.61
32.05
43.17
66.96
74.87
80.27
82.95
91.42
90.79
F-1
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