11
The procedure is the same when working in
metric units, but the velocity readings will be in
m/s. The opening area should be calculated in
m
2
, and the answer will be in m
3
/s.
EXAMPLE:
A rectangular opening measures 600 x 400 mm
(0.6 x 0.4 m) and twelve readings of velocity
have been taken. The readings are added
together and the result is divided by 12. In this
example, the average velocity is 3.025 m/s. The
opening’s cross-sectional area is: 0.6 x 0.4 m =
0.24 m
2
. Therefore, the volume flow rate is 0.24
m
2
x 3.025 m/s = 0.726 m
3
/s. This figure should
be multiplied by 3600 to arrive at cubic meters
per hour, or by 1000 to give the answer in liters
per second. 0.726 x 3600 = 2613.6 m
3
/h or
0.726 x 1000 = 726 l/s.
SECTION 6
Care and Maintenance
•
Remove batteries from instrument if not
used for an extended period of time.
•
Do
not
bend or touch blades, accuracy will
be affected.