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KD2 Pro Operator’s Manual
7. Care and Maintenance
Note: After repeated use the septum may begin to leak. Replacement
septums have been provided with your instrument. To replace simply
remove the cap, press the old septum out and press new one back in.
To conduct a performance verification, insert the needle fully
into the glycerol. The needle should be oriented vertically, and
it is best to turn the vial of glycerol upside-down on top of the
needle, so that any bubbles in the glycerol float to the top
away from the needle. The needle should be approximately
centered in the vial, and must not be touching a 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 cooling from direct air conditioning flow can
decrease the accuracy of the measurement. It is best to place
the needle and vial in an isothermal environment (e.g. insu-
lated chamber or cooler), and allow 15 minutes of equilibra-
tion time before taking the measurement. The thermal
conductivity of the glycerol is 0.285 W/(m· K) at 20 °C.
The two-hole Delrin block should be used to verify the per-
formance of the dual-needle (SH-1) sensor. The sensor should
be fully inserted into the pre-drilled holes in the Delrin, and
allowed to equilibrate for at least 15 minutes before taking the
measurement. Again, make sure that the system is not under-
going rapid temperature drift. Even the heat from holding the
block in your hand for a few seconds, or the cooling from
direct air conditioning flow can decrease the accuracy of the
measurement. It is best to place the needle and block in an
isothermal environment (e.g. insulated chamber or cooler),
and allow 15 minutes of equilibration time before taking the
measurement. The Delrin blocks have slightly different ther-
mal conductivities from lot to lot, so the correct values for K,
