WIKA TGT70 - Manual (Page 12)

14047194.02 02/2013 GB/D/F/E
12 WIKA operating instructions model TGT70
GB
■ If the sensor is 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.
■ Avoid welding or soldering and permanent fastening of the capillary as this could
seriously damage the capillary and impair the operation of the instrument.
■ The dial casing must be mounted free from vibration.
If necessary, it is possible to isolate the instrument from the mounting point 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, do not exceed the following limits:
Frequency range < 150 Hz
Acceleration < 0.7 g (7 m/s 2 )
6.2 Ambient conditions
Unless the ingress protection of the thermometer‘s housing is specifically identified in the
order confirmation, the instrument 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.
6.3. Indicator check
Indicator checks should only be carried out in comparison with a more accurate instrument
or, if possible, with a calibrated instrument. The temperature during the check must remain
constant. Fluctuating temperatures can lead to reading errors caused by the different
response times of the sensors.
Before checking the indicators of thermometers without thermowells, a waiting time of at
least 5 minutes with the stem's full length properly inserted is required to allow temperature
equalisation.
Temperature checks using thermometers with sensors assembled with thermowells can,
in many cases, only result in a reference temperature at the instrument under test, due to
permanent heat dissipation caused by the thermowell. In temperature applications fitted
with static checking thermometers (e.g. pipeline systems), permanent offsets in reference
temperatures can also be caused by the measuring path. Ambient temperatures around
the indicator case which differ substantially from room temperature can lead to steady
indication errors with constant ambient temperatures and to varying indication errors with
fluctuating ambient temperatures.
6. Commissioning, operation