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9.
RH Sensor Calibration
The Relative Humidity Sensor is calibrated using the same technique as for the calibration check.
The difference is in what happens to the results. The calibration calculation may be used to
calibrate the sensor, whereas the check calculation is only for information. Therefore, the first
portion of the sensor calibration is like the calibration check.
Some part numbers of items used during the test and calibration are given below for reference.
•
Sample Bottle
990-0153
•
Septa, Sample Bottle
990-0074
•
Capillary Tubes, 1.0
µ
l, 100/vial
990-0150
Carefully remove a capillary tube from the
storage bottle. Use tweezers to handle the tube.
Just touch the end of the tube into purified or de-
ionized water. The tube must be in contact with
the water long enough to fill. If the tube is not
full, the reading will be low.
Pull the capillary tube straight up out of the water. A rapid but straight motion will tend to
remove excess water from the side of the tube. Excess moisture on the side of the tube will
cause a high reading.
Visually verify that no free water is on the outside of the tube. Wipe the tube only if necessary
with a finger or other non-absorbent instrument. DO NOT WIPE THE TUBE WITH A TISSUE
OR OTHER OBJECT THAT WILL SOAK WATER OUT OF THE CAPILLARY TUBE.
Gently
place the tube into a dry sample bottle just past the bottle’s neck
as shown. Dropping or shaking the tube will cause water to be lost and
will give erratic readings over several tests.
Install a dry cap and septum on the sample bottle with the smooth,
shiny side of the septum to the inside of the bottle.
Gently
place the sample bottle onto the transport so that the tube
rests toward the neck of the bottle as shown.
