WIKA CTM9100-150 - Handbuch (Seite 20)

20 WIKA operating instructions, models CTD9100, CTB9100, CTM9100
11263911.02 05/2014 GB/D
GB
6. Commissioning, operation
6.4 Surface insert (only CTM9100-150)
The operation of the calibrator with the surface insert is
suited to a simple and the most accurate calibration possible
of surface probes.
Fit the insert, which is hollow and long from the bottom, into
the block using a special replacement tool.
The sleeve also has three bores (1 x 3 mm, 1 x 3.1 mm and
1 x 4 mm) directly under the surface, so that the correct
surface temperature can be controlled at all times.
Following use, the inserts should be removed using the
specific replacement tools and then the sleeve and block
should be cleaned. This prevents the sleeves becoming
jammed in the heating block.
The calibration of surface thermometers is
very difficult and not fully defined. Thermom-
eters mounted on surfaces dissipate heat
from the surface and create a cold zone on
the surface being measured. In the multi-
function calibrators, the calibration tempera-
ture is created in a specially designed
surface insert and an external reference
thermometer measures the temperature
directly under the surface. The reference
thermometer also determines the tempera-
ture of the cold zone through integration of
the temperature along the sensitive length
of the reference thermometer and thus
provides a true temperature calibration of
surface temperature sensors.
The sleeve is designed so that the supplied
external reference provides the best possi-
ble result, since the depth of the bore is
adjusted to the sensitive length. If a separate
external reference is used for comparison
calibration, ensure that the sensitive length
is known and it lies in the centre of the
calibration surface.
6.5 Infra-red insert (only CTM9100-150)
The operation of the calibrator with the infra-red insert is
suited to a quick and simple calibration of non-contact
thermometers.
Fit the hollow and specially-designed insert into the block
using a special replacement tool. The sleeve also has two
bores in the edge (1 x 3.5 mm and 1 x 4.5 mm) for the
accurate monitoring of the temperature.
The design and surface finish of the sleeve is important, in
order that a defined emissivity of 1 is achieved.
Following use, the inserts should be removed using the
specific replacement tools and then the sleeve and block
should be cleaned. This prevents the sleeves becoming
jammed in the heating block.
With temperatures of < 0 °C and higher air
humidity, ice or dew can form in the insert.
This can falsify the calibration. By capping
the measurement opening, the ice or dew
formation can be strongly reduced.
■ Leave the measurement opening closed
as long as possible
■ Open the measurement opening for a
short while for the measurement
■ Remove any ice or dew present by
heating
Surface insert Insert for infra-red measurements