WIKA TR12-M - Handbuch (Seite 12)

GB
4. Design and function
11419904.02 09/2013 GB/D
WIKA operating instructions models TR12, TC12 (Ex d) 12
4. Design and function
4.1 Description
The model TR12-B (resistance thermometer) and model TC12-B (thermocouple) electrical
thermometers are comprised of a module (TR12-M, TC12-M) which is built into a certified
Ex d housing. The module is made up of a spring-loaded measuring insert (TR12-A,
TC12-A) built into a neck tube. The measuring insert acts in conjunction with the neck tube
as a flameproof joint. The measuring insert (TR12-A, TC12-A) is replaceable.
The active measuring component of the measuring insert is manufactured from a welded
tube or from mineral-insulated cable, optionally in combination with ceramic-insulated
thermocouple wires. The sensor is embedded in ceramic powder, heat-resistant potting
compound, cement compound or thermally conductive paste.
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.
The connection side of the measuring insert consists of a transition sleeve with connected
bare wires.
Alternatively, the thermometers can be built into other certified housings (see appendix 2
“WIKA housings and equipment list”).
There are 3 different variants available:
■ Variant 1: The thermometer is fitted with an enclosure certified with an ignition protection
type of “flameproof enclosure”, in which the terminal block is fitted.
■ Variant 2: The thermometer is fitted with an enclosure certified with an ignition protection
type of “flameproof enclosure”, in which an electronic assembly is fitted.
■ Variant 3: The thermometer is fitted with certified equipment (transmitter) with an ignition
protection type of “flameproof enclosure”.
The thermometer is marked with II 2G Ex d IIC Gb and is suitable for zone 1.
The model TR12-B or TC12-B thermometers in variants 1 and 2 are built with Ex d certified
connection heads or series 1/4000, 5/6000 or 7/8000 WIKA connection enclosures. These
enclosures and covers are made from stainless steel or aluminium. The cover is optionally
available with a glass window.
CAUTION!
Thermometers of this model range must be installed with a thermowell (minimal
wall thickness: 1 mm). The design of the thermowells can be selected as
desired, but the operational process data (temperature, pressure, density and
flow rate) must be taken into account.