DURAG D-LX 721 User Manual

4 | Functional safety
28
D-LX 201/721
4.3 General applicable parameters for the flame monitor
Independent of its operating mode, the compact flame monitor possesses the follow-
ing general parameters:
Evaluated as per
DIN EN 61508 1-7
Type as per DIN EN 61508-2
Type B
Suitable for use at up to
SIL3
4.4 Operation with low and high demand modes
A safety-relevant system can be designed for low or high demand mode.
●
Operation with low demand mode
The rate of demand for the safety-related system does not exceed once per year.
●
Operation with high demand mode
The rate of demand for the safety-related system does exceed once per year.
The decision between the two operating modes is made based on the selected applic-
ation. The flame monitors being considered here can be used for both operating
modes.
4.5 Operation with low demand mode
If the flame monitor is used in the low demand mode, the following parameters apply:
Mode
Low demand mode
MTTR
24 hours
MRT
24 hours
λ
sd
+ λ
su
1748 FIT
λ
dd
1848 FIT
λ
du
33 FIT
SFF
99.1 %
DC
AVG
98.23 %
Depending on the selected interval (in years) for the proof test, the probability of a fail-
ure on demand occurring (Probability of Failure on Demand, PFD) is as follows:
Proof test interval in years PFD
AVG
1 7.01 * 10
-6
2 1.18 * 10
-5
3 1.66 * 10
-5
4 2.14 * 10
-5
5 2.63 * 10
-5
10 5.07 * 10
-5
15 7.54 * 10
-5

DURAG D-LX 721 Specifications

General

Brand	DURAG
Model	D-LX 721
Category	Measuring Instruments
Language	English