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

11 Supplement
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
22)
Static pressure
23)
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.

11.9 Dimensions, versions process component

The following dimensional drawings represent only an extract of the possible versions. Detailed
dimensional drawings can be downloaded at www.vega.com under " Downloads" and " Drawings".
Relating to the adjusted span.
22)
Relating to the measuring range end value.
23)
90
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 %
VEGADIF 85 • Modbus and Levelmaster protocol
10 years
< 0.15 % x TD
< ±0.15 %