Appendix C - Elevation And Suppression Corrections; How Adjustment Is Made - Siemens 7MF4033 series User Manual

UMSITRPDS3-1

13.0 APPENDIX C - ELEVATION AND SUPPRESSION CORRECTIONS

When installing a transmitter to measure liquid level, configuration of the Sensor Input Block often must
include an adjustment for one of two conditions introduced by the mounting arrangement:
•
Elevated Span - The Lower Range Value (LRV) of the transmitter needs to be configured
above "0." See Figure C-1.
•
Suppressed Span - The LRV of the transmitter needs to be configured below "0." See
Figure C-2.
Max. Range
Span
Min. Range
Elevated Span: To
calculate maximum
distance, subtract
actual span setting
from range limit given
in specification.
FIGURE 13-1 Elevated Span
A brief discussion of how to make adjustments for elevation and suppression follows. Then two examples
of the calculations needed to determine configuration parameters are given. Finally, a brief procedure that
does not involve calculations is provided.

13.1 HOW ADJUSTMENT IS MADE

Because the transmitter can handle elevation and suppression simply by setting parameters, it is not
necessary to introduce mechanical measures, such as installing piping backwards or adding additional
hardware.
The range of the transmitter can be set anywhere, forward or reverse acting, as long as the following
criteria are met:
LRL ≤ LRV ≤ URL
LRL ≤ URV ≤ URL
Span = [URV - LRV] ≥ Min Span
Note that the URL (Upper Range Limit), LRL (Lower Range Limit), and Min Span are transmitter
dependent.
November 2005
HP Shut-Off
Valve
Vent
Span
MG00363b
Vent
HP LP
Appendix C - Elevation and Suppression Corrections
Fill Connection
LP Shut-Off
Valve
Suppressed
Max. Range Span
Min. Range
HP Shut-Off
Valve
Distance X
FIGURE 13-2 Suppressed Span
See
Section 9
Specifi-
cations
for range
limit.
LP line
filled with
condensate
MG00363b
HP
LP
13-1