Emerson Rosemount 1199, Reference Manual, Page: 82 / 104

4.2 DP Level transmitter installation best practices
Pressure transmitters have a sensor module with a primary fill fluid. Therefore, the
mounting position of a standard transmitter with silicon fill could read approx ±1.25 inH
2
O
worst case after installation. This is simply zeroed out using a Field Communicator after
installation so that it will read zero pressure. With a remote seal attached you have
additional components that will create additive pressure that would increase the amount
of potential shift. This would include the secondary fill fluid in the remote seal assembly
along with the potential of torqueing effects when the assembly is bolted to the process.
For these reasons, the transmitter’s digital output will most likely not match the exact
values calculated on paper. Even a redundant transmitter would most likely not read the
exact digital values after being installed. For these reasons, a re-range function is common
practice after all installations.
Figure 4-8: Installation Example
Pressure transmitter Pressure transmitter with remote seals
A. Primary fill
B. Secondary fill
What is important is the calculated span (level height × specific gravity of the process).
After the transmitter is mounted, it is common and best practice to re-range the
transmitter so that the 4 mA point will be the installed digital value. The 20 mA point
would then be set based on the calculated span value setting it above the installed digital
value.
The procedure would be based on mounting configuration (zero based) 4 mA = 0 inH
2
O or
(non-zero based) 4 mA exceeds the ±3% of the upper sensor limit (USL).
4.2.1 Open tank (zero based)
With open tank level applications this value can typically be zeroed out using a HART
device as long as it is < 3% USL. The maximum value that can be zeroed out is 3% of the USL
or 7.5 inH
2
O for a range 2 (250 inH
2
O) sensor.
Configuration Reference Manual
May 2020 00809-0100-4002
82 Rosemount DP Level