GasSecure GS01
Safety Manual
CERTIFICATIONS
15
8.
CERTIFICATIONS
AND
FAILURE
RATE
DATA
The GS01 gas detector has gone through rigorous reliability and functional safety
assessments and has been certified to IEC 61508:2010 Parts 1, 2, and 3.
The below listed failure rates are valid for operating stress conditions typical of an
industrial field environment similar to IEC 60654-1 with an average temperature of
40
o
C.
Table 8-1: SIL parameters GS01 detector
Parameter
GS01 Config-1, -129,
-65, -193
GS01 Config-2, -130,
-66, -194
Product Life
15 years
Safe Failure Fraction (SFF)
91%
Safe Detected (SD) failure rate [1/h]
0
Safe Undetected (SU) failure rate [1/h]
1.97 E-7
Dangerous Detected (DD) failure rate [1/h]
9.66 E-7
Dangerous Undetected (DU) failure rate [1/h]
1.00 E-7
Safety Integrity Level (SIL)
2
Diagnostic Test Interval
120 min
Safety accuracy
6
Concentration
is
not
underestimated by more
than 15%LEL or 40% of
the true concentration,
whichever is greater.
Concentration
is
not
underestimated by more
than 15%LEL or 40% of
the true concentration,
whichever is greater.
Average Probability of Failure on Demand
(PFD
AVG
) [1/h]
1.61E-3
7
Probability of dangerous Failure per Hour
(PFH) [1/h]
1.08 E-7
8
Worst
case
response
time
incl.
communication
60 sec
Fail safe values (data type Float)
NaN (0x7FC00000)
9
for the process value (PV)
“Bad” (decimal value < 64) for the PV status byte
Fail safe values (data type INT16)
-21846 (0xAAAA) for the process value (PV)
“Bad” (decimal value < 64) for the PV status byte
The calculated “Probability of Failure on Demand” assumes a “Mean Time to
Restoration” (MTTR) of 24 hours and a maintenance capability of 100%.
It is assumed that the field device is installed in a Safety Instrumented System
(SIS) operating in a Low Demand or High Demand environment per IEC 61508.
The GS01 gas detector is regarded as Type B field device per IEC 61508 with a
hardware fault tolerance of 0 (zero).
6
Assumed that the detected gas mixture is either a mixture of methane and air (Config-1 and
Config-129) or a mixture of propane and air (Config-2 and Config-130)
7
For a proof test interval of 2 years.
8
Fault detection and reaction time is 2 hours. Max demand rate is 1/200 hours.
9
Per float definition in IEEE754.
