Aalborg Totalizer - Manual (Page 10)

7
f.3 GAIN Adjustment (required only if potentiometer
R12 GAIN was accidentally readjusted)
1. Carefully remove front panel from the Totalizer.
2. Set potentiometer R8 (SCALE) into completely up position
(CW direction).
3. Connect the Totalizer to the transducer (see e.1).
4. Using a digital multimeter connected to the 0 to 5 Vdc signal at
the output of transducer, set the output rate on the transducer to
full scale (5 Vdc). Connect a second digital multimeter with
selected frequency function (resolution of 4-1/2 digit is required)
to pin [T5] on the Totalizer printed circuit board. Maintain full
scale flow (5000 mV output from transducer) and adjust the
potentiometer R12 (GAIN) for frequency reading of 5.000 kHz
+ 10 Hz.
5. Maintain 2% full scale flow (100 mV output from transducer) and
adjust the potentiometer R19 (OFFSET) for frequency reading of
100 Hz
+ 2 Hz.
6. Maintain again full scale flow (5000 mV output from transducer)
and adjust the potentiometer R12 (GAIN) for frequency reading
of 5.000 kHz
+ 10 Hz.
f.4 Re-Scaling of Totalizer (if necessary)
It may be desirable to re-scale the Totalizer for different flow ranges or
engineering units.
To change flow range:
1. Calculate the Fs factor which is flow rate specified in UNIT/SEC.
( i.e. standard liters per second [L/sec.], standard cubic
centimeters per
second [mL/sec], etc.)
Fs = Fm/60;
where:
Fm = Full scale range in [UNIT/MINUTE] for which your transducer
has been calibrated (usually shown on the front label). If engineering
unit is not minute based it has to be converted. For example 300
SCFH has to be converted to 300/60 = 5 cubic feet/minute.