WIKA TC10-L - Manual (Page 12)

3370964.05 04/2014 GB/D/F/E
12 WIKA operating instructions models TR10-L, TC10-L (Ex d)
GB
4. Design and function
4.1 Description
The model TR10-L (resistance thermometer) or TC10-L (thermocouple) electrical
thermometers are comprised of a measuring insert which is built into a certified Ex d
housing. In combination with a flame path fitting that is screwed into the head, the measuring
insert functions as a flameproof joint. The measuring insert (TR10-K, TC10-K) is replaceable.
Sensor design in model TR10-L
The measuring resistor is embedded in ceramic powder, heat-resistant potting compound,
cement compound or thermally conductive paste. A one-sided sealed tube, which is welded
to a mineral-insulated cable, forms the external shell of the sensor tip of the measuring
insert.
Sensor design in model TC10-L
The measuring insert of the thermocouple is manufactured from mineral-insulated cable.
The thermocouple consists of the internal leads of the mineral-insulated cable. The weld
spot of the thermocouple is, depending on the design, either ungrounded welded with the
sheath of the mineral-insulated cable or grounded welded.
If the temperature sensor is designed as a grounded thermocouple, the thermocouple is
joined directly to the sheath. Designs with a diameter smaller than 3 mm and with grounded
thermocouples should be considered as galvanically connected with earth potential.
Versions (see figures page 18):
■ Thermometers without a flame path fitting may only be used in combination with a
solid-machined, certified WIKA thermowell with a minimal wall thickness of 1 mm. The
thermometer is marked with IIC and is suitable for use in zone 1.
■ After installation of a flame path fitting into the connection head of the thermometer, a
thermowell is no longer mandatory for certification reasons. In most cases, however,
the use of a thermowell (solid-machined or fabricated, with a wall thickness of 1 mm) is
necessary for process engineering reasons. The thermometer is marked with IIB + H
2
and
is suitable for use in zone 1.
The design of the thermowell can be selected as desired, but the operational process
data (temperature, pressure, density and flow rate) must be taken into account. If a solid
WIKA thermowell is already available or installed, a flame path fitting is not necessary.
The thermometers models TR10-L or TC10-L are manufactured by WIKA with certified
Ex d connection heads or connection housings. These enclosures and covers are made
from aluminium or stainless steel. The cover is optionally available with a glass window.
4. Design and function