HD2114P/HD2134P
- 17 -
V2.3
To set the measurement in inch
2
, select the "SECT m2" menu item, and using the UNIT key, change
the unit of measurement from m
2
to inch
2
. Proceed to enter the data using the arrows: confirm with
ENTER. The area inserted as above remains in the memory so the flow rate measurements can be
repeated on other identical vents, without having to set the area again.
The area comprised must be between 0.0001m
2
(1cm
2
) and 1.9999m
2
.
After input of the duct's section area, select the unit of measurement for the flow rate by using the
UNIT/DuctCALC key: l/s, m
3
/h and ft
3
/min.
The display shows the calculated flow rate on the
section set
with the parameters "SECT m2" and "SECT INC2".
To obtain the correct flow rate measurement, the fact that the air speed is not constant on the section
but varies from point to point needs to be considered, therefore an
average
speed over the entire
section is required. Furthermore, the speed varies through time at the same point.
This is particularly true when the surface considered is wide or when turbulence is generated, near a
grid or diffuser. The anemometers provide some solutions in order to obtain correct measurements
even in presence of these disturbance phenomena.
1) Spatial averaging (
Duct Calc
function)
It is always best to perform the measurements at different points and consider the average value
as the valid data. Using the
Duct Calc
function (sub-function of the UNIT key), these
anemometers can capture more than one measurement and supply the maximum, average, and
minimum value. In particular, the average value (AVG) is the most important as it supplies the
average speed, and therefore the calculated flow rate
along the entire section
and not on a single
measurement point.
Procedure:
Using the UNIT key, select the
speed
or
flow rate
unit of measurement for which you wish to
obtain the average, maximum, and minimum.
Enable the calculation function by pressing simultaneously the UNIT/DuctCALC and
FUNC/Enter keys: the central line of the display shows the instantaneous value of the selected
variable (
speed or calculated flow rate
) while the lower line figure indicates the number of
times the measurement has been logged.
The measurement can be interrupted and there are no time limits to abide by between two
subsequent measurements. The captured values are not erased, so it is possible to get some
samples, turn the instrument off and later turn it back on again to proceed with the logging of
more samples without losing the measurements already carried out. The maximum number of
samples is 99.
To reset the calculation, before enabling the Duct Calc function, press FUNC until the message
"FUNC CLR" appears, then use the arrows to select YES and confirm using ENTER.
Position the probe in the first measurement point and press HOLD/
to capture the first point
value.
Repeat the same procedure with all the other points that you feel it is necessary to capture, by
pressing HOLD/
each time: the indicator will provide the total number of acquired samples.
After recording the first sample or at the end of the capture, press FUNC/ENTER. The MAX,
MIN and average values of the chosen quantity, that is,
the speed or calculated flow rate on
the entire section
will be displayed, according to the variable selected at the beginning of the
measurement.
To end the function, press ESC.
Generally, the greater the number of captured measurements (maximum 99) the greater
the accuracy of the result obtained.
