WIKA TC12-M - Handbuch (Seite 24)

GB
7. Information on mounting and operation in hazardous areas
14083458.01 09/2013 GB/D
WIKA operating instructions models TR12, TC12 (Ex i) 24
surface temperatures for use in potentially explosive dust atmospheres and permissible
ambient temperatures can be seen from the relevant approvals and must be observed.
Thermal backflow from the process, that exceeds the permissible ambient temperature of
the transmitter, must not be allowed to occur. It must be prevented by installing suitable heat
insulation or a neck tube of suitable length.
If the wall thickness is below 1 mm, the instruments must not be subjected to ambient
stresses that may have an adverse effect on the partition wall. Alternatively, a thermowell of
suitable minimum wall thickness may be used.
When using a thermowell/neck tube, the overall instrument must be designed such that it
allows installation in a way that results in a sufficiently tight gap (IP 67) or a flameproof gap
(EN/IEC 60079-1) towards the less hazardous area.
When housings are used, they must either have their own suitable approval or comply with
the minimum requirements. IP protection: at least IP 20 (at least IP 65 for dust), applies to
all housings. However, light metal housings must be suitable in accordance with EN/IEC
60079-0 section 8.1. In addition, non-metallic housings or powder-coated housings must
meet the requirements of EN/IEC 60079-0 or have a suitable warning note.
Protection measures for applications that require EPL Ga or Da:
Operationally based friction or impacts between light metal instrument components or their
alloys (e.g. aluminium, magnesium, titanium or zirconium) and instrument components from
iron/steel, are not permitted. Operationally based friction or impacts between light metals
are permitted.