Emerson Rosemount 935, Reference Manual

Page: 71 / 76

E SIL-2 features
This appendix details the special conditions to comply with the requirements of EN 61508
for SIL-2.
The Rosemount 935 open path combustible gas detector can be used in low and high
demand mode applications. See IEC 61508-4:2010, Chapter 3.5.16.
E.1 Safety relevant parameters
Type: B
Structure: 1oo1
HFT: 0
Mean time to repair: 72 hours
Ambient temperature: maximum 149 °F (65 °C)
Proof test interval: 52 weeks (1 year)
λ
S
= 2056.1 fit
λ
D
= 1976.1 fit
λ
DU
= 114.8 fit
λ
SD
= 1933.4 fit
λ
DD
= 1861.4 fit
SFF = 97% DC = 94%
PFD
avg
= 6.45 x 10
-4
PFD
%_SIL2
= 6.4%
PFH = 1.15 x 10
-7
1/h PFH
%_SIL2
- 11.5%
E.2 General conditions for safe use
• The Rosemount 935 should consist only of the approved hardware and software
models.
• Consider the application advice and limitations of the Manual. For calibration and
maintenance, consider the regional and national regulations.
• The 24 V power supply must fulfill the requirements for PELV/SELV of EN 60950.
• The HART
®
and RS-485 interfaces are not allowed to be used for the transmission of
safety related data.
• The alert conditions according to SIL-2 can be implemented by an alert signal via the
20 mA current loop.
• After installation and configuration, the operator must verify the set-up parameters
and check the function of the Rosemount 935.
Reference Manual SIL-2 features
00809-0100-4035 May 2022
Rosemount 935 71