Siemens SITRANS FUS1020, Manual, Page: 149 / 251

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1020NFM-1D
Section 6
Using Actual Zero
NOTE: Flow must be stopped with the line blocked (if possible) before invoking this function.
To invoke Actual Zero:
Access the [Zero Flow Adjust] option list by pressing the <Right Arrow>.
Press <ENTER>. A pop-up window prompts you to set the current flow rate (in selected rate
units) to equal zero (0.000).
NOTE: If a flow offset is desired (i.e., to test analog outputs) then press <Right Arrow> to
enable numeric entry.
Press <ENTER> to start the Actual Zero process.
When you send the command, the flow computer analyzes the current flow rate for up to sixty sec-
onds, integrating (averaging) the data for the best zero correlation. During this time, the menu prompt
at the top of the display screen shows a timer that counts from zero to sixty. You can allow zero
averaging for the entire period, or cancel the process at any time by pressing the <ENTER> key. This
controls the amount of data the meter averages to obtain a zero level.
Using ReversaMatic
If site conditions do not permit stopping the flow rate at the mounting location, and you do not know the
current flow rate, then you can use the ReversaMatic routine to establish the zero flow level. You
should perform the ReversaMatic procedure as quickly as possible to ensure that the flow rate re-
mains constant throughout the procedure.
To invoke ReversaMatic:
z
To access the [Zero Flow Adjust] option list press the <Right Arrow>.
z
Move the cursor to [ReversaMatic]. Press <ENTER> to invoke the routine.
z
The meter begins to measure the positive flow rate. “Positive” flow refers to flow moving from
upstream transducer location to the downstream transducer location. Note top prompt line
shows:
z
Upon completion, the meter beeps and the display screen shows:
z
Now remove then remount the upstream and downstream transducers in their reversed positions.
Mount the Up transducer (without removing its cable) in the Down transducer/cable location. Mount
Down transducer with its cable in the Up transducer/cable location. When remounting the trans-
ducers, couple them to the pipe properly. Press <ENTER> (after re-installing the transducers).
z
The flow computer measures the negative flow rate briefly, then beeps and repeats the prompt:
z
Now remount the transducers for normal operation (in their original orientation). When remounting
transducers, couple them to the pipe properly. Press <ENTER> (after re-installing the transduc-
ers).
Reverse Xdcrs / Press ENT
Reverse Xdcrs / Press ENT
Reversamatic Action