Measuring Accuracy - Siemens SITRANS F Additional Operating Instructions

TECHNICAL DATA
5

5.5 Measuring accuracy

The flowmeter measures with the same accuracy in both operation modes, in the non-SIL mode
as well as in the SIL mode, as long as the device is intact.
But diagnostic measures need a reasonable gap between the states intact and defect for
availability reasons. Therefore, a safety engineer integrating the flowmeter into the overall
system must take the higher measurement inaccuracy into consideration.
The following figure illustrates the logical coherences.
- 0.75%
Figure 5-1: Measuring accuracy vs. flow
x: Flow
y: Measuring accuracy
1 Bounds for non-SIL, device intact (designed, tested)
2 SIL bounds (supervised)
3 Actual inaccuracy, noise etc.
28
y
4%
0.75%
- 4%
www.siemens.com/flow
SITRANS FX330
x
10/2017 - A5E40875009-AB EN