Ahlborn ALMEMO 710 - 14.5 Volume flow measurement

14. Wizards
Example
M3.1=
M
von M0.0 .. M3.0
14.5 Volume flow measurement
To determine the volume flow in flow channels multiply together the average
flow velocity
v
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
• cross-section area QF:
VS =
v
.
QF
.
0.36 VS = m
3
/h,
v
= m/s, QF = cm
2
To calculate average flow velocity
v
from approximate air volume mea-
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 Flow 0.0
Select Function channel ´Average value´ Function channel ´Average value´ 0.1
Display Average velocity
v
Average value 13.24m/s
Select channel type Channel type Tubular
Enter diameter in mm Diameter 0150 mm
Volume flow, display 0.2 Volume flow 834.m3/h
For the calculation, display, output, and saving of the volume flow the
function channel ´Flow´ is provided. (see 13.2.13).
72 ALMEMO
®
710
M3.1=(
∑
i=M0.0
n=M3.0
M
i
)/N
M=(
∑
i=Bk2
n=Bk1
M
i
)/N
M0 M1 M2 M3 M4...
0.0
0.1
0.2
0.3
3.0
3.1
3.2
3.3
4.0
4.1
4.2
4.3
1.0
1.1
1.2
1.3
2.0
2.1
2.2
2.3
1.chann.
2.chann.
3.chann.
4.chann.
Sensor channels
M9
9.0
9.1
9.2
9.3
