Siemens SITRANS LUT400 Operating Instructions Manual page 189

2.12.1.3. Temperature Source
Source of the temperature reading used to adjust the speed of sound.
Options
With this default, the SITRANS LUT400 uses the transducer's internal
temperature sensor (standard in all Siemens EchoMax Transducers).
If the transducer does not have an internal temperature sensor, Fixed
Temperature value, or an External TS-3 temperature sensor can be used.
If the acoustic beam atmosphere temperature varies with distance from
the transducer, connect a TS-3 Temperature Sensor and Ultrasonic/
Temperature Transducer, and select Average of Sensors (Transducer and
TS-3).
In gasses other than air, the temperature variation may not correspond
with the speed of sound variation. In these cases, turn off the temperature
sensor, select value Fixed Temperature, and set a fixed temperature [see
Fixed Temperature (2.12.1.4.)].
If Ultrasonic/Temperature Transducer, TS-3 Temperature Sensor, or
Average of Sensors value is selected, faults on the temperature sensors
will be displayed if the sensor appears open or short.
When a transducer temperature sensor fault occurs, Temperature Source
can be set to FIXED. This allows the device to continue measuring (and no
cable fault will display), until the transducer is replaced. Once replaced, set
Temperature Source back to its original setting.
2.12.1.4. Fixed Temperature
Use this feature if a temperature sensing device is not used.
Values
Enter the temperature (in °C) of the atmosphere within the transducer
acoustic beam. If the temperature varies with distance from the
transducer, enter the average temperature.
2.12.1.5. Sound Velocity at 20 degrees C
This value is used to automatically calculate sound velocity.
Values
If the acoustic beam atmosphere sound velocity at 20°C (68 °F) is known,
and the sound velocity vs. temperature characteristics are similar to that
of air (344. 1 m/s), enter the sound velocity. Units displayed in meters per
second (m/s).
A5E33329501 SITRANS LUT400 (HART) – OPERATING INSTRUCTIONS
* TRANSDUCER
FIXED TEMPERATURE
EXTERNAL TS-3
AVERAGE OF SENSORS (Transducer and TS-3)
Range: -100.0 to +150.0 °C
Default: +20.0 °C
Range: 125.000 to 20000.000 m/s
Default: 344 13 m/s
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