SICK FLOWSIC600, Technical Information, Page: 74 / 262

74 FLOWSIC600 · Technical Information · 8010125 V 4.0 · © SICK AG
Flow Calibration
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3.2.3.3
Adjustment using piece wise linear error interpolation
With this method the flow rate error E(Q) (deviation as found from meter under test (MUT)
related to the reference meter) will be corrected to zero (

Figure 21 ). Of course, an exact
correction to zero is only possible at the flow test points because only there the real
deviation from the reference meter is known.
Figure 21 Graphical display of results of a piece wise corrected error curve
The MEPAFLOW600 CBM calibration wizard calculates the adjust factors AF(Q
i
) for every
flow test point in a way, that, when you multiply the adjust factor with the Q
act(MUT)
, the
result is the same value as the reading of the reference meter. After the adjustment the
deviation as left is exactly zero. These 'test point' adjust factors are calculated as follows:
The 'test point' errors E(Q
i
) are entered in the column "Dev. as found [%]" (

pg. 89,
Figure 38 ). The error values of the flow test points are stored in the meter in the form of K-
factors according to:
To correct the flow rate errors to zero between two adjacent flow test points i and i+1, a lin-
ear interpolation is used. During normal meter operation a flow rate dependent error of the
meter is calculated according to:
During normal meter operation the error correction is carried out with a flow rate depen-
dant adjust factor according to:
If the actual flow rate is less than the flow rate of the first data point, or greater than the
flow rate of the last data point, the error characteristic will be fixed to the last value and not
interpolated. The meter will indicated an "Adjust range error" (see "Meter status" window).
AF Q
i
 
1
1
E Q
i
 
100
%
-------------- +
------------------------ =
K Q
i
 
1
E Q
i
 
100
%
-------------- +
1
AF Q
i
 
------------------- = =
E Q
 
Err
i
Err
i 1 +
Err
i
–
Q
i 1 +
Q
i
–
---------------------------------
Q Q
i
–
  
+ =
Where Q
i
< Q < Q
i+1
and i the index of the flow test point
closest to the current flow rate.
AF Q
 
1
1
E Q
 
100
%
------------- +
----------------------- =