Sound Velocity - Siemens HydroRanger 200 HMI Operating Instructions Manual

2.7.4. Dimension A
2.7.5. Dimension L
Reading
2.12.4. Decimal Position
2.12.5. Convert Reading
2.12.6. Offset Reading
OCM
2.13.2. Primary Measuring Device
2.13.4. 1 . Flow Exponent
2.13.5. PMD Dimensions
2.13.4.2. Maximum Head
2.13.4.3. Maximum Flow
2.13.4.5. Zero Head
2.13.4.4. Flow Time Units
2.13.4.6. Flowrate Decimal
2.13.4.7. Flowrate Units
2.13.6. 1 . 1 . Head 1
2.13.6. 1 .2. Flow 1
Totalizer
2.7.7. Inflow/discharge Adjust
2.14.4. Totalizer Decimal Position
2.14.5. Totalizer Multiplier

Sound Velocity

The sound velocity of the transmission medium is affected by the type, temperature, and
vapor pressure of the gas or vapor present. As preset, the HydroRanger 200 HMI
assumes the vessel atmosphere is air at 20°C (68°F). Unless altered, the sound velocity
used for the distance calculation is 344.1 m/s (1129 ft/s).
Variable air temperature is automatically compensated when a Siemens ultrasonic/
temperature transducer is used. If the transducer is exposed to direct sunlight, use a
sunshield or a separate TS-3 temperature sensor.
Also, if the temperature varies between the transducer face and the liquid monitored, use
a TS-3 temperature sensor (submerged in the liquid) in combination with an ultrasonic /
temperature transducer. Set
transducer and TS-3 measurements.
Atmosphere composition other than air can pose a challenge for ultrasonic level
measurement. However, excellent results may be obtained by performing a Sound
Velocity Calibration (
mixed), at a fixed temperature, and under consistent vapor pressure.
The HydroRanger 200 HMI automatic temperature compensation is based on the sound
velocity / temperature characteristics of "air" and may not be suitable for the atmosphere
present. If the atmosphere temperature is variable, perform frequent Sound Velocity
Calibrations to optimize measurement accuracy.
Page 242 HydroRanger 200 HMI – OPERATING INSTRUCTIONS
2.11.1.4. Temperature Source
2. 1 1.1.8. Auto Sound Velocity
136
137
172
172
173
174
175
180
176
176
178
177
178
178
180
181
137
184
184
for both, to average the
) if the atmosphere is homogeneous (well
A5E36281317