Dimensions, Versions Process Component - Vega VEGADIF 85 Operating Instructions Manual

F = 0.25 %
T
3. Determination of deviation and long-term stability
Deviation
Measuring range
10 mbar (1 kPa)/0.145 psi
30 mbar (3 kPa)/0.44 psi
100 mbar (10 kPa)/1.5 psi
500 mbar (50 kPa)/7.3 psi
3 bar (300 kPa)/43.51 psi
16 bar (1600 kPa)/232.1 psi
Long-term stability
Measured variable
Differential pressure
21)
Static pressure
22)
4. Calculation of the total deviation - digital output signal
- 1. step: Basic accuracy F
F = √((F ) + (F ) )
2 2
perf T Kl
F = 0.25 %
T
F = 0.065 %
Kl
F = √(0.25 %) + (0.065 %)
2
perf
F = 0.26 %
perf
- 2. step: Total deviation F
F = F + F
total perf stab
F = 0.26 % (result of step 1)
perf
F = 0.065 % x TD
stab
F = 0.065 % x 2
stab
F = 0.13 %
stab
F = 0.26 % + 0.13 % = 0.39 %
total
The total percentage deviation of the measurement is thus 0. 39%. The absolute total deviation is
0. 39% of 250 mbar = 1 mbar
The example shows that in practice the error of use can be significantly higher than the actual
measurement error. The causes are temperature influence and turn down.

12.5 Dimensions, versions process component

The following dimensional drawings represent only an extract of the possible versions. Detailed
Relating to the adjusted span.
21)
Relating to the measuring range end value.
22)
VEGADIF 85 • Profibus PA
TD 1 : 1 up to 5 : 1 TD > 5 : 1
< ±0.1 %
< ±0.065 %
1 year
< 0.065 % x TD
< ±0.065 %
perf
)
2
total
TD > 10 : 1
< ±0.02 % x TD
< ±(0.035 % + 0.01 %) x TD
< ±(0.015 % + 0.005 %) x TD
< ±(0.035 % + 0.01 %) x TD
Time range
5 years
< 0.1 % x TD
< ±0.1 %
12 Supplement
10 years
< 0.15 % x TD
< ±0.15 %
87