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Note Concerning DO9847 Version
AP471, AP472 and AP473 probes can work connected to a DO9847 only if this is provided with
the 2.0 firmware version, or with a later one. Previous versions do not support these probes. To
check which is your firmware version, open the menu and select INFO: VER 2 REV 0 indication
corresponds to version 2.0.
Firmware versions prior to 2.0 can be factory upgraded.
Flow Measurement
The measurement of air flow requires to know the area of the pipe or of the vent perpendicular to
the flow: to set this parameter, DO9847 units are provided with a specific function. Open
DO9847 menu (2.0 version, or superior), select “7) Utility” and then “1) Area calculations”.
See page 24 for a detailed description of this function.
Note:
when measuring flow, use only one anemometric probe at any one time
because the
function allows to configure one only area. On the contrary, several anemometric probes,
as well as other kinds of probes, can be used contemporaneously when measuring air ve-
locity.
Operating
If you move the probe inside a stream, velocity and flow can change both their position through-
out the space (from a point to another) and their performance over the time (in the same position,
but in subsequent moments): this is particularly true when the involved area is quite big and
when some turbulences are generated in front of a ventilating grill or of a diffuser. The DO9847
unit provides some solutions to get a correct measurement even before these elements of distur-
bance.
1) Space Average (Record Function)
It is always suggested to record more measurements in different positions and to consider as
valid data only average values. By means of the
Record
function, the DO9847 can acquire
several measurements and provide, at the end, maximum, minimum and average values.
Press <6/RCD> to activate the Record function. Use the <F3> function key to reset any prior
measurement, then place the probe in the first point to be measured and press F2 (function
key) M(n=00) to acquire the first value. Repeat these steps for each other point to be meas-
ured and press <F2> each time: the M(n=…) indicator, in the middle of the commands bar,
will indicate the number of acquired samples. After acquiring, press <5/DataCall>: press ei-
ther F1, F2 or F3 to read the min, max, and average value of the three quantities: velocity,
temperature and flow.
In general, the bigger the number of acquired measurements is, the higher the accuracy of the
results will be.
