Instructions for Use
– SCHMIDT
®
Flow Sensor SS 20.700
Page 4
2 Application range
The
SCHMIDT
®
Flow Sensor SS 20.700
(art. no.: 562 140) is designed
for stationary measurement of the flow velocity as well as the temperature
of air and gas with operating temperature from -
20 … +120 °C and working
pressure
1
up to 16 bar.
The sensor is based on the measuring principle of a thermal anemometer
and measures the mass flow of the measuring medium as flow velocity
which is output in a linear way as standard velocity
2
w
N
(unit: m/s), based
on standard conditions of 1013.25 hPa and 20 °C. Thus, the resulting out-
put signal is independent of the pressure and temperature of the medium
to be measured.
When using the sensor outdoors, it must be protected against di-
rect exposure to the weather.
Versions
„Oxygen (O
2
) > 21 %
“ and
„ Grease-free and Oxygen (O
2
) > 21 % (PWIS-free)
“
The variant "
Oxygen (O
2
) > 21 %
", which is suitable for use in concen-
trated oxygen, differs constructively from the standard version only by
the use of a special compression fitting. Its sealing O-ring consists of
BAM
3
-approved FKM which is coated with an oxygen-suitable lubri-
cant.
The
variant “
Grease-free and Oxygen (O
2
) > 21 % (PWIS-free)
” is also
suitable for the use in concentrated oxygen but in addition its com-
pletely free of any lubricant. Aside from that the seal of the compres-
sion fitting is realized with a clamping ring made of stainless steel thus
there are no synthetics which comes in contact with the medium. The
sensor can also be used in applications where paint-wetting impair-
ment substances (PWIS) are not acceptable.
The sensor, its accessories and the packaging have been cleaned espe-
cially according to the standard IEC/TR 60877:1999.
This standard restricts the use of the sensor to biatomic oxygen O
2
(small
residual amounts of ozone are acceptable nevertheless).
Improper handling of gas mixtures with an oxygen content of more
than 21 % or pure oxygen can lead to fires or explosions.
1
Overpressure
2
Corresponds to the actual velocity under standard conditions
3
BAM: Bundesanstalt für Materialforschung und
–prüfung (german federal authority)
