FMT230, FMT250
THERMAL MASS FLOWMETER | CI/FMT230/250-EN REV. B
23
Inlet and outlet sections
The figures below show the recommended inlet and outlet
sections for various installations.
Figure 6: Inlet and outlet sections
Installation
Inlet section
Outlet section
A
Pipe extension
min. 15 × DN
min. 5 x DN
B
Pipe reduction
min. 15 × DN
C
90° Pipe elbow
min. 20 × DN
D
2 × 90° pipe elbow in one
level
min. 25 × DN
E
2 × 90° pipe elbow in two
levels
min. 40 × DN
F
Turn-off device
min. 50 × DN
To achieve the specified measuring accuracy, the indicated inlet
and outlet sections are required.
In case of combinations of several inlet-side errors, e.g. valve and
reduction, a longer inlet section must always be taken into
account.
In case of confined spaces at the installation site, the outlet
section can be shortened to 3 × DN. However, reducing the
specified inlet section will reduce the achievable level of
accuracy.
A high repeatability of the measured value is maintained.
In case of insufficient inlet and outlet sections, a special
calibration may be possible. To do this, a detailed alignment is
necessary for individual cases.
The specified inlet and outlet sections must be doubled for
gases with a very low density (hydrogen, helium).
Installation at high ambient temperatures
Figure 7: Mounting position at high ambient temperatures
Under high but permissible ambient temperatures, avoid
additional thermal stress from heat convection or radiation,
since these sources of heat may exceed the permissible ambient
temperature on the equipment surface.
If the device needs to be installed directly on a hot, horizontal
piping, we recommend installing it on the side. In such cases,
you should avoid installing it in the 12 o'clock position, otherwise
the warm air that rises up will cause additional heating of the
electronics.
Sensor insulation
1
Insulation
Figure 8: Isolation of the sensor
The sensor may be insulated as shown in
Figure 8
.
