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Sierra Instruments Instruction Manual
Smart-Trak
®
2 Series 100
24
Smart-Trak 2 Features
Setpoint Adjustment
The setpoint (command) input signal you supply to Smart-Trak 2 must be a direct
linear representation of 0% to 100% of the mass flow full-scale value. Apply the
setpoint signal from pin 8 to any of the analog grounds (see Chapter 2 for wiring
details). A setpoint value of 0 VDC or mA (or 1 VDC or 4 mA) will regulate the
flow to 0% and a setpoint value of 5.00 VDC (or 10 VDC or 20 mA) will adjust the
flow to 100% of the instrument’s full scale range.
When the setpoint (command) signal is applied, the flow controller will reach the
setpoint value within two seconds to within ±2% of the selected flow rate.
CAUTION: DO NOT LEAVE A SETPOINT APPLIED FOR AN
EXTENDED PERIOD OF TIME TO A CONTROLLER WHEN THE
GAS SUPPLY IS SHUT OFF OR BLOCKED.
Damage may result and the
instrument will become hot to the touch. Instead, see below for use of the
“Valve Close” feature which allows you to disable the valve while
maintaining the setpoint signal. This may be set by the Pilot Module, the
Smart-Trak 2 Software, or an external analog signal.
Changing the Output or Setpoint Signals
To modify the analog output or setpoint signals (from 4-20mA to 0-10Vdc, for
example), you must use the Pilot Module or the Smart-Trak 2 Software. The data
label will indicate the form these signals had when the instrument was last
calibrated. We strongly recommend that you adapt the data label if the
configuration is changed for future reference. See Chapter 4 or 5 for the necessary
procedure.
Over-Range Condition
If the mass flow rate exceeds the full-scale range listed on the Smart-Trak 2 data
label (see samples on page 2-1), the output signal will measure above full-scale.
However, the device has not been calibrated for flows in excess of the calibrated
full scale value and the value will be both non-linear and inaccurate if an over-range
condition exists. Please be aware that the analog outputs can exceed full scale by as
much as 20%, or more.
Once the over-range condition has been removed, it may take up to 30 seconds for
the Smart-Trak 2 to recover and resume normal operation. An over-range condition
will not harm the instrument.