Verifying Sensor Performance - Decagon Devices KD2 Pro Operator's Manual

6 MAINTENANCE AND TROUBLESHOOTING KD2 Pro
6.3

Verifying Sensor Performance

The KD2 Pro ships with three standard materials you can use to ver-
ify that the sensors are operating according to specifications. These
three materials are a clear vial of glycerin (glycerol) for the KS-1 Sen-
sor, a white plastic cylinder for the SH-1 needle sensor, and a TR-1
Verification Standard for the TR-1 and RK-1 single needle sensors.
Use the glycerol to verify KS-1 Sensor performance. The cap of
the vial has a septum that allows direct insertion of the needle into
the vial for verification.
Note: After repeated use the septum may begin to leak. We pro-
vide replacement septums with your instrument. To replace simply
remove the cap, press the old septum out and replace with a new one.
To conduct a performance verification, insert the needle fully into
the glycerol. Orient the needle vertically and turn the vial of glyc-
erol upside-down on top of the needle. Holding the vial upside down
ensures that any bubbles in the glycerol float to the top away from
the needle. Center the needle in the vial, without touching any side
of the vial. Before taking a measurement in the glycerol, make sure
that the system is not undergoing rapid temperature drift. Even the
heat from holding the vial in your hand for a few seconds, or the cool-
ing from direct air conditioning flow can decrease the accuracy of the
measurement. (Section 5.4 details the best practices for measuring
liquids.) It is best to place the needle and vial in an isothermal en-
vironment (e.g. insulated chamber or cooler), and allow 15 minutes
of equilibration time before taking the measurement. The thermal
W
conductivity of the glycerol is 0.285 at 20 C.
(m K)
Use the two-hole Delrin block to verify the performance of the dual-
needle (SH-1) sensor. Fully insert the SH-1 sensor into the pre-drilled
holes in the Delrin and allow it to equilibrate for at least 15 minutes
before taking the measurement. Make sure that the system is not
undergoing rapid temperature drift. Slight temperature differences
from sources like body heat or AC can decrease the accuracy of the
measurement. It is best to place the needle and block in an isother-
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