78
10 Supplement
WIKA Operating Instructions - Differential pressure transmitter DPT-20
10.4 Calculation of the total deviation - Practical example
Data
Differential pressure 250 mbar (25 KPa), medium temperature on the measuring cell 60 °C
DPT-20 with measuring range 500 mbar
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 = 500 mbar/250 mbar
TD =
2 : 1
2. Determination temperature error F
T
Measuring range
-10 … +60 °C / +14 … +140 °F
-40 … -10 °C / -40 … +14 °F und
+60 … +85 °C /+140 … +185 °F
10 mbar (1 kPa)/0.145 psi
< ±0.15 % + 0.20 % x TD
< ±0.4 % + 0.3 % x TD
30 mbar (3 kPa)/0.44 psi
< ±0.15 % + 0.10 % x TD
< ±0.2 % + 0.15 % x TD
100 mbar (10 kPa)/1.5 psi
< ±0.15 % + 0.15 % x TD
< ±0.15 % + 0.2 % x TD
500 mbar (50 kPa)/7.3 psi
< ±0.15 % + 0.05 % x TD
< ±0.2 % + 0.06 % x TD
3 bar (300 kPa)/43.51 psi
16 bar (1600 kPa)/232.1 psi
< ±0.15 % + 0.15 % x TD
< ±0.15 % + 0.20 % x TD
F
T
= 0.15 % + 0.05 % x TD
F
T
= 0.15 % + 0.1 %
F
T
= 0.25 %
3. Determination of deviation and long-term stability
Deviation
Measuring range
TD 1 : 1 up to 5 : 1 TD > 5 : 1
TD > 10 : 1
10 mbar (1 kPa)/0.145 psi
< ±0.1 %
< ±0.02 % x TD
30 mbar (3 kPa)/0.44 psi
100 mbar (10 kPa)/1.5 psi
< ±0.065 %
< ±(0.035 % + 0.01 %) x TD
500 mbar (50 kPa)/7.3 psi
3 bar (300 kPa)/43.51 psi
< ±(0.015 % + 0.005 %) x TD
16 bar (1600 kPa)/232.1 psi
< ±(0.035 % + 0.01 %) x TD
Long-term stability
Measured variable
Time range
1 year
5 years
10 years
Differential pressure
23)
< 0.065 % x TD
< 0.1 % x TD
< 0.15 % x TD
23)
Relating to the adjusted span.
