M&C TechGroup PMA 50 EEX Operator's manual - Manual (Page 36)

36
Gas sampling and gas conditioning technology 9-3.15-ME
Safety handbook according to SIL
Contemplated devices
It was contemplated the PMA 50 EX with part no. 05A1000(a) and the following options:
- Ventilation equipment and enclosure purging (part no. 05A9005 and 05A9000),
- Measuring cell solvant resistant or with glass solder (part no. 90A0009 u. 90A0006)
- Transmitter for measurements of gases from ex-zone 0 II 1/2 G EEx de [ia] IIC T5
Excluded are the
PMA 50 EX/P/PD… with pressure compensation, part no. 05A2500(a) as well
as the options 0-20mA outlet, part no. 05A2505(a) resp. zero suppression, part no. 05A9015.
Device description and safety function
The safety function of the device is the measurement of the oxygen concentration in the measu r-
ing cell which is provided as linear current signal 4-20mA. The status relay as transmission of a
summary fault indication is element of the safety function. Current signals <3,2mA and > 20,5mA
as well as an open status contact have to be evaluated as failure from a downstream device.
The SIL-qualification is valid for all adjustable measuring ranges. It applies for alarm of rising ox-
ygen concentration (dangerous fault: oxygen signal is to small) as well as for alarm of decreasing
oxygen concentration (dangerous fault: oxygen signal is too big).
For one channel and two channel operation of the oxygen analyser PMA 50 Ex the following parame-
ters have been determined.
Single channel 1oo1 Redundant 1oo2 Single channel 1oo1
Redundant
1oo2
Safety function
Mesurement of the oxygen
concentration
Mesurement of the oxygen
concentration
Dangerous error Oxygen signal too low Oxygen signal too big
Measuring range Depending on the measuring task Depending on the measuring task
Device type
B
(but without µP and software)
B
(but without µP and software)
Proof test interval 1 year 1 year
MTTR 24 hr 24 hr
SFF 91,3 % 96,4 %
HFT 0 1 0 1
SIL –ability

2

2


factor
—

5 % —

5 %
PFD 3,83 Ч 10
-4
1,93 Ч 10
-5
1,66 Ч 10
-4
8,34 Ч 10
-6

du
8,44 × 10
-8
(per hr) 3,52 × 10
-8
(per hr)

dd
4,62 × 10
-7
(per hr) 4,62 × 10
-7
(per hr)

su
4,25 × 10
-7
(per hr) 4,74 × 10
-7
(per hr)

sd
5,70 × 10
-11
(per hr) 5,70 × 10
-11
(per hr)