Bronkhorst®
Instruction Manual ES-FLOW™ 1xxC
9.17.153A
21
Prerequisites
Zeroing an instrument requires that:
·
the ambient conditions (temperature, pressure) match those of the operating environment of the instrument
·
the instrument is filled homogeneously and pressurized with the operational media, according to the typical process
conditions
·
there is absolutely no flow through the instrument; preferably, this is achieved by closing a valve immediately after the
outlet of the instrument (control valve, shut-off valve)
Blocking the flow through the instrument is essential; zeroing an instrument while there is still a flow will lead to
measurement errors.
Procedure
The zeroing procedure can be performed manually (using the multifunctional switch) or digitally, with RS-232 or fieldbus
communication
Regardless of the chosen method, the zeroing procedure takes approximately 25 seconds to complete.
5.6.1
Manual procedure
To start the autozero function with the multifunctional switch, follow these instructions:
1. Change the setpoint of the instrument to 0 (zero)
2. Press and hold the multifunctional switch. After 4 seconds, the red LED
l
will light up; another 4 seconds later the red
LED will extinguish and the green LED
l
will light up
3. At that moment (which is after 8 to 12 seconds), release the switch
The green LED will start to blink fast, indicating that the autozero function is in progress. After (successful) completion, the
green LED will glow continuously, while the output signal is 0% (parameter
Measure
= 0).
5.6.2
Digital procedure
FlowPlot and FlowSuite provide an easy way to adjust the zero point of an instrument with RS-232 communication; the
Autozero
function automatically performs the procedure described here.
To adjust the zero point using digital communication, set parameter values in the following sequence (see section
for more information about instrument parameters):
Sequence #
Parameter
Value
Action
1
Setpoint
0
stop flow (close control valve)
2
Init Reset
64
unlock secured parameters
3
Control Mode
9
enable calibration mode
4
Calibration Mode
0
reset calibration mode
5
Calibration Mode
9
start zeroing
On completion of the procedure, parameter
Control Mode
returns to its initial value. If the procedure is successful, parameter
Calibration mode
changes to 0 (idle). If the procedure fails,
Calibration Mode
changes to 255.
After performing the procedure, remember to set parameter
Init Reset
to value 0 to lock secured parameters.
