WIKA 70-8xx - Manual (Page 11)

11
11472988.02 04/2013 GB/D/F/E
WIKA operating instructions expansion thermometer, model 70
GB
„ Protect capillaries against bending. The smallest bending radius of the capillary should
not be less than 6 mm. Any bending or discontinuities of the capillary may result in the
failure of the instrument.
„ If the sensor is installed in a location which is exposed to shock and vibration, it is
essential that the capillary is coiled in several loops between the last attachment point
and the sensor, and free from tension. Any excess length must also be coiled, since
cutting would render the instrument unserviceable.
„ The welding or soldering of the capillary, as well as all permanent fixing of the capillary,
should be avoided, since this can seriously damage the capillary and can impair the
operation of the instrument.
„ The dial casing must be mounted free from vibration. If necessary, it is possible to
isolate the installation from the mounting point, e.g. by installing a flexible connection
line between the measuring point and the thermometer and mounting the instrument on
a suitable bracket.
If this is not possible, the following limit values must not be exceeded:
Frequency range < 150 Hz
Acceleration < 0.5 g (5 m/s 2 )
The liquid filling must be checked on a regular basis.
The liquid level must not drop below 75 % of the gauge diameter.
Heavy shocks, oscillations and vibrations lead to imprecise values, increased wear in the
transmission mechanism, and fractures on welded or soldered joints.
In thermometers with built-in micro switches, the contacts can chatter as a result of
vibrations, which can lead to an increase in contact wear and a displacement in the
desired contact point.
6.2 Ambient conditions
Unless the ingress protection of the thermometer‘s housing is specifically identified
in the order confirmation, the instruments must be protected from humid air and other
aggressive atmospheres.
To ensure the best measuring accuracy possible, the ambient temperature on the
indicator case should be between 0 ... 40 °C. Higher or lower ambient temperatures can
cause indication errors.
6. Commissioning, operation