SFAM
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Festo – SFAM – 2017-09c English
±0.1 %FS/K x 17 K = ±1.7 %FS. (
è
Fig. 14)
x = measured variable (flow rate)
y = measurement value (display)
z = display value error sought
x
y
z
Fig. 14
Temperature fault
The maximum temperature error is calculated as follows:
±1.7 %FS = ±1.7 % x 1000 l/min =±1.7/100 x 1000 l/min = ±17.00 l/min
If a measured value of 600 l/min is displayed, the maximum temperature error range is thus calculated
as follows:
±17 l/min x (600 l/min)/(1000 l/min)= ±10.2 l/min
With a display of 600 l/min at the sensor and an ambient temperature of 40 °C, due to the temperature
error range the actual flow rate through the sensor values can have values in the range
589.8 … 610.2 l/min.
The total error of the sensor at 6 bar/0.6 MPa and 40 °C is calculated as follows:
Total error = (±precision error range) + (± precision error zero point) + (±temperature error range
at40 °C)
= (±18 l/min) + (±3 l/min) + (±10.2 l/min)
= ±31.2 l/min
With a display of 600 l/min at the sensor and an ambient temperature of 40 C, the actual flow rate
through the sensor can have values in the range 568.8 … 631.2 l/min.
e) Error cause by pressure influence
If the sensor is also not operated in the pressure range at nominal conditions (6 bar, 23 °C), a
pressure-dependent range must also be taken into account in determining the overall error. In
determining the error as a result of the pressure dependency, the same approach should be used as
when determining the temperature error.
