Emerson Rosemount 2240S, Reference Manual, Page: 67 / 194

57
Reference Manual
00809-0100-2240, Rev DA
Configuration/Operation
October 2017
Configuration/Operation
Converting from WLS to tank reference system
To convert from the reference system of the water level sensor (WLS) to the reference system of the tank,
the distance
X needs to be calculated by using the following formula:
X = (R-L1) - (L-L2)
X=distance between the Tank Zero Level and the Water Zero Level.
L=distance between Water Zero Level and mark on the upper part of the WLS.
R= Tank Reference Height. This is the distance between the Tank Reference Point and the Tank Zero Level.
L1=distance between the Tank Reference Point and the temperature sensor flange.
L2=distance between the mark on the top of the WLS and the temperature sensor flange.
See Figure 5-5 on page 55 for illustration of the different geometry parameters related to the water level
sensor.
Sensor limits
Conversion from the WLS reference system to the tank reference system is handled by the Rosemount
2240S transmitter. In the tank reference system, the Lower Sensor Limit (0%) and the Upper Sensor Limit
(100%) are given by the following formulas:
Upper Sensor Limit (100%) = L
A
+ X
Lower Sensor Limit (0%) = X
where L
A
is the active length of the Water Level Sensor, and X is the distance between the Water Zero
Level and the Tank Zero Level (Minimum Water Distance) as described above. See Figure 5-5 on page 55
and examples in section “Configuration examples” on page 59 .
Upper and lower measurement limit
In case Upper and Lower Dead Zones are used to reduce the measurement range (see “Upper and lower
dead zone” on page 56 ), the resulting measurement limits are calculated using the following formulas:
Upper Measurement Limit (100%) = (L
A
+ X) - UDZ
Lower Measurement Limit (0%) = X + LDZ,
where
L
A
=active length of the water level sensor
UDZ=Upper Dead Zone
LDZ=Lower Dead Zone
See Figure 5-6 on page 56 for an illustration of how the measurement range is affected by the Upper and
Lower Dead Zones.