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14. Wizards
Sensor channels
4.chann.
0.3
1.3
2.3
3.chann.
0.2
1.2
2.2
2.chann.
0.1
1.1
2.1
1.chann.
0.0
1.0
2.0
M0 M1 M2 M3
14.5 Volume flow measurement
To determine the volume flow in flow channels multiply together the average
v
flow velocity
and the cross-section area
The ´Volume flow´ wizard contains all the necessary functions.
1. An average value has been obtained using a flow probe (units m/s)
based on a previous averaging process. (see 14.4)
2. Functions for calculating the cross-section, i.e. ´diameter´, ´length´, ´width´
3. A function channel for the volume flow (see 13.2.13.1).
4. Calculation of the standard volume flow at 20 °C ambient temperature
and 1013 mbar atmospheric pressure
Volume flow VS = average flow velocity
v
VS =
To calculate average flow velocity
surements at air vents and gratings the time-based averaging mode can be
used (see 14.4.2 and Manual 3.5.5). Apply the rotating vane at one end, start
averaging, and proceed uniformly over the whole cross-section; when you
reach the other end of the cross-section stop averaging.
With Pitot tubes, in order to calculate actual velocity, both temperature com-
pensation and atmospheric pressure compensation are required. (see
12.2.5, 12.2.6).
Select Measuring channel
Select Function channel ´Average value´
Display Average velocity
Select channel type
Enter diameter in mm
Volume flow, display
For the calculation, display, output, and saving of the volume flow the
function channel ´Flow´ is provided. (see 13.2.13).
72
ALMEMO
3.3
4.3
9.3
3.2
4.2
9.2
3.1
4.1
9.1
3.0
4.0
9.0
M4...
M9
. QF . 0.36
v
®
710
M=(
Example
M3.1=(
M3.1=
v
• cross-section area QF:
v
3
VS = m
/h,
v
from approximate air volume mea-
Flow
Function channel ´Average value´
Average value
Channel type
Diameter
0.2 Volume flow
n=Bk1
∑
M
)/ N
i
i=Bk2
n=M3.0
∑
M
)/N
i
i=M0.0
M
von M0.0 .. M3.0
2
= m/s, QF = cm
13.24m/s
0150 mm
834.m3/h
0.0
0.1
Tubular
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