Siemens SITRANS Probe LU Operating Instructions Manual page 56

Using Sound Velocity Calibration
Ensure a steady level at some low value (P653 and P654 adjusted accordingly).
1. Allow sufficient time for the vapor concentration to stabilize.
2. Press the measurement key
3. Repeat step 2 at least five times to verify repeatability.
4. Measure the actual reading (use tape measure).
5. Enter the actual value.
6. Repeat this procedure if the atmosphere type, concentration, or temperature
conditions are different from when the last sound velocity calibration was
performed.
In gases other than air, the temperature variation may not correspond with the
Note:
speed of sound variation. Use P660 and P661 to select a temperature source, and use a
fixed temperature.
P652 Offset Correction
Stores the fixed offset value determined when an Offset Calibration is performed.
Values
Related
Alternatively, if the amount of Offset Correction required is known, enter the amount to be
added to the Reading before display.
P653 Velocity
Notes:
• P653 can only be accessed by entering the parameter number.
• The user cannot change the value of P653 directly, but can affect it via P654 or by
P660/P661.
Displays the value adjusted based on the Sound Velocity at 20
Temperature (P664) characteristics of air.
Values (view only)
Related
The units used depend on the setting for P005:
• m/s if P005 = 1, 2, or 3
• ft/s if P005 = 4 or 5.
Page 50 SITRANS Probe LU (HART) – OPERATING INSTRUCTIONS
to display the calculated reading.
Range
• P650 Offset Calibration
Range
50.01 to 2001 m/s (164.1 to 6563 ft/s)
• P651 Sound Velocity Calibration
• P654 Sound Velocity at 20
• P660/P661 Temperature setting
–99999 to 99999
o
C (P654) versus
o
C
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