Mechanical Mounting - WIKA TC84 Manual De Instrucciones

5. Commissioning, operation

5.2 Mechanical mounting

Ceramic protection tube materials withstand changes in temperature only to a limited
extent. A temperature shock can therefore easily result in stress cracks and consequently
in damage to the protection tube.
EN
For this reason, preheat thermocouples with ceramic or sapphire protection tubes before
installation, and then slowly immerse them into the hot process.
In accordance with DIN 43724, an insertion speed of 1 cm/min is recommended for
protection tubes with a diameter of 24/26 mm. For smaller diameters of 10/15 mm, the
speed can be increased to 50 cm/min. As a basic principle, higher process temperatures
require a lower insertion speed.
In addition to the protection from thermal stress, ceramic protection tubes must also be
protected from mechanical loads. The reason for these harmful stresses are bending forces
in case of a horizontal mounting position. As a consequence, an additional support must
be provided in case of a horizontal mounting position depending on the diameter, greater
nominal lengths and the design.
In principle, the deflection problem also occurs for metal protection tubes, particularly for
insertion lengths > 500 mm. For process temperatures > 1,200 °C [> 2,192 °F], vertical
mounting should be preferred.
The flange dimensions must match those of the mating flange on the process side. The
seals used must be suitable for the process and the flange geometries (consult the delivery
note). When mounting, depending on the seals used, use the appropriate tightening
torques and tools (e.g. torque spanner).
5.3 Electrical mounting
Cable glands
Requirements for meeting ingress protection:
Only use cable glands within their indicated clamping range and operating temperature
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(cable diameter suitable for the cable gland).
Do not use the lower clamping area with very soft cable types.
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Only use round cables (if necessary, slightly oval in cross-section).
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Do not twist the cable.
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Repeated opening/closing is possible; however only if necessary, as it might have a
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detrimental effect on the ingress protection
For cables with a pronounced cold-flow behaviour the screw connection must be fully
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tightened.
12 WIKA operating instructions model TC84