65
9 Supplement
WIKA Operating Instructions - Process pressure transmitter IPT-2x
To provide a better overview, the formula symbols are listed together below:
•
F
total
: Total deviation
•
F
perf
: Basic deviation
•
F
stab
: Long-term stability
•
F
T
: Thermal change of zero signal and output span (temperature error)
•
F
Kl
: Deviation
•
F
a
: Thermal change of the current output
•
FMZ: Additional factor measuring cell version
•
FTD: Additional factor Turn down
9.3
Calculation of the total deviation - Practical example
Data
Pressure measurement in the pipeline 4 bar (400 KPa), product temperature 40 °C
IPT-2x with measuring range 10 bar
, deviation < 0.1 %, process fitting G1 (piezoresistive measuring
cell)
The required values for the temperature error F
T
, deviation F
Kl
and long-term stability F
stab
are avail-
able in the technical data.
1. Calculation of the Turn down
TD = 10 bar/4 bar, TD = 2.5 : 1
2. Determination temperature error F
T
(TD 1:1)
T / °C
50 °C
40 °C
20 °C
10 °C
-40 °C
100 °C
150 °C
0,15
-0,15
-0,3
-0,45
-0,6
-0,75
-0,9
0,3
0,45
0,6
0,75
0,9
F/
%
TBasis
Fig. 35: Determination of the basic temperature error for the above example: F
TBasis
= 0.15 %
Accuracy class
In the compensated temperature range of 10 … +70 °C
0.075 %, 0.1 %
0.2 %
Factor FMZ
1
3
Tab. 28: Determination of the additional factor measuring cell for above example: F
MZ
=
1
Turn Down
TD 1 : 1
TD 2.5 : 1
TD 5 : 1
TD 10 : 1
TD 20 : 1
Factor FTD
1
1.75
3
5.5
10.5
Содержание IPT-2x
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