WIKA CTD9300 - Handbuch (Seite 58)

9037926 03/2005
58 WIKA Operating Instructions CTD 9300 Rev. 1
Temperature Dry Well Calibrators CTD 9300
4. Operating the Calibrator
GB
4.8 Notes of the DKD
Extract from the instructions of the DKD expert committee
”Temperature and Humidity” on the use of temperature dry well
calibrators.
The calibration certificate of a DKD calibration laboratory confirms
that the temperature dry well calibrator fulfils the high demands
placed on the calibration capabilities of a calibrator of that kind, as
defined in guide line DKD-R 5-4. Nevertheless, the following issues
must be taken into consideration when using the calibrator:
The calibration of temperature dry well calibrators primarily refers to
the temperature of the solid block. The temperature of the
thermometer to be calibrated in the block can deviate from that
temperature. If a thermometer of the same type under the same
measuring conditions as used for the calibration is used, it can be
assumed that the errors of measurement when calibrating ideal
thermometers is not larger than the errors of measurement
specified in the calibration certificate.
If not specified otherwise in the calibration certificate, it must be
ensured that:
„
the measuring element is in a homogenous temperature zone.
„ the inside diameter of the bore or adapting sleeve used in the
calibrator in the temperature range of from -80 °C to 660 °C is
max. 0.5 mm and in the temperature range of from 660 °C to
1,300 °C max. 1.0 mm larger than the outside diameter of the
thermometer to be calibrated.
„ the immersion depth of the thermometer to be calibrated is at
least 15 times the outside diameter of the thermometer to be
calibrated.
„ the thermometer to be calibrated has an outside diameter of
d <_ 6 mm.
When calibrating thermometers with an outside diameter of
d > 6 mm, an additional error of measurement due to heat
dissipation must be taken into consideration.
If measurements of this kind are to be performed, the additional
heat dissipation for the thermometer type you are testing can be
determined by your DKD calibration laboratory.