Measurements In Insulation; Measurements In Liquids - Decagon Devices KD2 Pro Operator's Manual

KD2 Pro
5.3

Measurements in Insulation

KS-1 Insulation measurements are best taken using a ten minute read
time. The long read time minimizes contact resistance errors, and the
low heat of the KS-1 needle reduces free convection errors. Always
drill a hole in foam insulation for the sensor. Manually pushing in the
needle can cause the insulation to bunch in front of and around the
needle resulting in a poor fit and a consequently a faulty reading. In
fiber type insulation materials, assure that the insulating materials
are not unduly disturbed by the needle insertion. (i.e. pushed in
front of the needle tip). Do not allow the sensor to move during the
measurement.
5.4

Measurements in Liquids

We designed the KS-1 sensor to measure thermal conductivity and
resistivity of liquid samples. However, measuring thermal properties
of liquids is difficult and great care must be taken to obtain accu-
rate and repeatable results. For an accurate measurement of thermal
properties of a liquid sample, the sample must be absolutely still in
relation to the KS-1 sensor. Convection, or bulk movement of the
sample, causes errors in the thermal properties measurement. Er-
ror from convective heat exchange is often very large, rendering the
thermal properties measurement useless.
Note: We did not design the TR-1 and SH-1 sensors for thermal
properties measurement in liquids. They do not return accurate re-
sults in those materials.
Convective heat exchange in fluids can be broken down into two cat-
egories: forced and free convection. Forced convection occurs when
the fluid is agitated or mixed by mechanical forces. Free convection
may occur when a body of higher or lower temperature is present in
a fluid. The temperature difference between the body and fluid cre-
ates density gradients in the fluid, and these density gradients cause
the fluid to mix. From a practical standpoint certain steps can be
taken to minimize both forced and free convective heat exchange.
5 TAKING MEASUREMENTS
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