Aalborg AFC - Manual (Page 13)

5. OPERATING INSTRUCTIONS
5.1 Preparation and Warm Up
It is assumed that the Mass Flow Meter or Controller has been correctly installed
and thoroughly leak tested as described in section 2. Make sure the flow source
is OFF. Power up the transducer using your own power supply (or turn the
POWER switch to the ON position at the front panel of your SDPROC Command
Module). Allow the Mass Flow Meter or Controller to warm-up for a minimum of
15 minutes.
During initial powering of the AFM/AFC transducer, the flow output signal will be
indicating a higher than usual output. This is indication that the AFM/AFC trans-
ducer has not yet attained it's minimum operating temperature. This condition will
automatically cancel within a few minutes and the transducer should eventually
zero.
CAUTION: If the valve is left in the AUTO (control) or OPEN mode
for an extended period of time, it may become warm or even hot to
the the touch. Use care in avoiding direct contact with the valve
during operation.
5.2 Flow Signal Output Readings
The flow signal output can be viewed on the panel meter, digital multimeter, or
other display device used as shown in figure 2-1.
When using the accessory SDPROC Command Module the flow rate will appear
on the display at the front panel. The observed reading is a 0 to 100% indication
(direct engineering units are optional). [If using a multichannel readout, be sure
that the CHANNEL selector switch is set to the correct channel.]
Analog output flow signals of 0 to 5 VDC or optional 4 to 20 mA are attained at
the appropriate pins of the 15-pin "D" connector (see Figure 2-3) on the top of the
AFM/AFC transducer. The output flow signal is also available at the DATA con-
nector on the rear panel of the SDPROC Command Module.
The default calibration is performed for 0-5 VDC output signal. If 4-20 mA output
signal is used for flow indication on the AFC, the accuracy of the actual flow rate
will be in the specified range (+1.0%) of full scale, but the total uncertainty of the
output reading may be in the range of +2.0% of full scale. Optional calibration for
4-20 mA output signal is available upon request at time of order.
Meter signal output is linearly proportional to the mass molecular flow rate of the
gas being metered. The full scale range and gas for which your meter has been
calibrated are shown on the flow transducer's front label.
For optional RS232 or IEEE488 interfaces please contact your distributor or
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