General Tools and Instruments DCFM8906 v.1 - Manual (Page 16)

readings on the upper readout—without clearing the meter’s
multi-point memory, press the HOLD button. To clear the
multi-point memory, press and hold the AVERAGE MULTI-
POINT button until the beeper sounds twice.
CONVERTING TO AIRFLOW VOLUME
MEASUREMENTS
The DCFM8906 can make and display real-time, maximum,
minimum and average airflow volume measurements at a
single point or multiple points. To enable the meter to make
these measurements, you must enter the free area
dimensions of the grille or register through which the air
source flows. The meter then multiplies this area by air speed
measurement(s) for that point or points to determine any
airflow volume value (real-time, maximum, minimum, or
average) desired.
As a practical matter, General recommends entering the free
air dimensions of the grille or register whose output you are
measuring before measuring the air speed through it. If you
enter the area ahead of time, you can quickly display the
airflow volume associated with any air speed by pressing one
button, without having to stop to enter the target area.
To enter the free area dimensions of a grille or register, power
the meter on and press the MODE VELOCITY FREE AREA
FLOW button. The lower readout will go blank and the upper
readout will display the value 1.111 ft
2 (with the first digit
flashing) under the indication AREA (Fig. 7).
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