Schmidt SS 20.600 - Square Cross-Section System Installation

Instructions for Use – SCHMIDT
®
Flow Sensor SS 20.600 Page 15
Thus, it is possible to calculate the standard volume flow of the medium
using the measured standard flow velocity in a pipe with known inner di-
ameter:
AwV
wPFw
DA
NN
NN




2
4

D
Inner diameter of pipe [m]
A
Cross-section area of pipe [m
2
]
N
w
Flow velocity in the middle of the pipe [m/s]
N
w
Average flow velocity in the pipe [m/s]
PF
Profile factor (for pipes with a circular cross-section)
N
V

Standard volume flow [m
3
/s]
SCHMIDT Technology provides a "flow calculator" on its homepage for
the calculation of flow velocity or volume flow in (circular) pipes or (rectan-
gular) shafts for different sensor types:
www.schmidt-sensors.com or www.schmidttechnology.de
Installation in systems with square cross-section
For most applications, two limit cases can be distinguished with regard to
flow conditions:
 Quasi-uniform flow field
The lateral dimensions of the flow-guiding system are approximately as
large as its length in the flow direction and the flow velocity is small so
that a stable trapezoidal
9
speed profile of the flow is formed. The width
of the flow gradient zone at the wall is negligible in relation to the cham-
ber width so that a constant flow velocity can be expected over the
whole chamber cross-section (the profile factor is in this case 1). The
sensor must be mounted here in such a way that its sensor head is far
enough from the wall and it measures in the area with the constant flow
field.
Typical applications are:
o Exhaust ventilation shafts for drying processes
o Chimneys
9
A uniform flow field prevails in the largest part of the space cross-section.