NT INTEGRATED FLOW CONTROLLER WITH DEVICENET COMMUNICATION
19
Entegris, Inc. | User Guide
Maintenance
NORMAL OPERATION
—
During normal operation, the stan-
dard NT Integrated Flow Controller
with DeviceNet communication
requires no maintenance, other than
a periodic re-zero of the unit.
RE-ZERO FUNCTION
—
The no flow calibration of the flow
controller can be re-zeroed, meaning
that the flow output that corresponds
to zero flow may be reset.
NOTE: When executing the re-zero
function, there must be at least 7 kPa
(1 psig) of static pressure. Optimum
pressure for re-zero is the operation
pressure, typically greater than 69 kPa
(10 psig).
NOTE: The following procedure must
be followed precisely to ensure proper
flow controller re-zero.
The no flow calibration of the flow
controller can be re-zeroed, meaning
that the flow output that corresponds
to zero flow may be internally reset.
This is done with DeviceNet service
requests. The ‘Zero_Adjust’ service
command in the Analog Sensor
Object is sent to begin a re-zero
process. The ‘Stop_Zero_Adjust’
service command in the Analog
Sensor Object is sent to stop the
re-zero process.
When the re-zero function is
activated, the flow controller valve
module will close fully to ensure that
fluid is not flowing. The unit will verify
the no-flow condition, and then re-
zero the flow module. The entire
re-zero function is completed in
10 seconds.
In order to obtain best performance,
the re-zero function should be
performed, at minimum if possible,
every day of service when operating
at ambient temperature conditions.
The re-zero function should be per-
formed more often if operating at
higher temperature. It is also recom-
mended to perform a re-zero after
start-up and after fluid temperature
changes of greater than 5°C (41°F).
Best performance will be achieved
by re-zeroing between each dis-
pense cycle.
Autozero Function
The no flow calibration of the flow
controller can be autozeroed,
meaning that the flow output that
corresponds to zero flow may be
automatically, internally reset when-
ever the setpoint is zero. Selecting
the ‘enabled’ setting of the ‘Autozero
Enable’ attribute in the Analog Sensor
Object does this. This is the default
setting.
