Schmidt SS 20.261, Инструкция по эксплуатации

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Instructions for Use SS 20.261 Page 8
This table lists the minimum values required in each case. If the listed
straight conduit lengths cannot be achieved, measurement accuracy
may be impaired
4
.
Calculation of volume flow
If the cross section area of the pipe is known, the output signal of the
flow speed can be used to calculate the standard volumetric flow of the
medium. By means of a correction factor PF
5
, which depends on the
pipe diameter the measured value can be converted to an averaged flow
w
N
which is constant over the whole pipe cross-section.
Thus, it is possible to calculate the standard volumetric flow of the
medium using the measured standard flow velocity in a pipe with known
inner diameter:
EF A w V
w PF w
D A
N N
N N
  
 
 

2
4

The measuring unit factor EF serves only for convenient conversion to
non-SI measuring units, for example m
3
/h (see Table 2).
SCHMIDT Technology provides a convenient calculation tool to
compute flow velocity or volume flow in pipes for all its sensor types and
measuring ranges. This “Flow Calculator” can be directly used on or
downloaded from SCHMIDT homepage:
http://www.schmidttechnology.de/de/sensorik/download/FlowCalculator.zip
Measuring unit of diameter D
EF m cm mm
Mea
s
u
ring
u
n
it
v
o
lume
tr
ic
f
low
m
3
/s 1 1,0E-04 1,0E-06
m
3
/min 60 6,0E-03 6,0E-05
m
3
/h
3600 3,6E-01 3,6E-03
l/s 1000 1,0E-01 1,0E-03
l/min 6,0E+04 6 0,06
l/h 3,6E+06 360 3,6
Table 2
4
Alternatively flow rectifier could be used, e.g. honeycomb ceramics.
5
Considers the parabolic flow profile and the sensor obstruction.
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 circular cross-sections)
EF
Measuring unit factor (conversion to non-SI units)
N
V

Standard volumetric flow [m³/s]