E2S STExB2X05, Instruction Manual, Page: 8 / 16

E2S Warning Signals Impress House, Mansell Road, Acton, London W3 7QH www.e2s.com Tel: +44 (0)208 743 8880
Document No. D199-00-201-IS Issue 5 28-11-22 Sheet 8 of 8
Figure 9: Changing of Lens.
Fit the guard back on to the lens and casting, align the holes
of the guard, lens and casting. To reattach the lens, the fixings
MUST be in the order shown in Figure 10.
Figure 10: Lens & Guard Fixings Order.
11) Maintenance, Overhaul and Repair
Maintenance, repair and overhaul of the equipment should
only be carried out by suitably qualified personnel in
accordance with the current relevant standards:
EN60079-19/IEC60079-19 Explosive atmospheres –
Equipment repair, overhaul and reclamation
EN 60079-17/IEC60079-17 Explosive atmospheres –
Electrical installations inspection and maintenance
Units must not be opened while an explosive atmosphere is
present.
If opening the unit during maintenance operations a clean
environment must be maintained and any dust layer removed
prior to opening the unit.
Repair of the flameproof threaded joints and cemented joints
is not permitted.
Potential electrostatic charging hazard - Clean only with a
damp cloth.
12) SIL 2 Reliability Data
Reliability and Functional safety IEC/EN61508 which has
been assessed and is considered suitable for use in low
demand safety function:
1. Random Hardware Failures and Architectural constraints
(route
2
H
).
2. As an unvoted item (i.e. hardware fault tolerance of 0) at
SIL 2.
The product was assessed against failure modes:

Failure respond to an input by lighting a beacon.

Spurious light output despite no input.
3. When employing the device in a SIL2 compliant system
the user should ensure frequent or continuous automatic
monitoring of continuity.
Integrity in respect of failure to
function
SIL2
& SIL1
Total Failure rate
0.
48
pmh
“Hazardous” failure rate (revealed) 0
pmh
“Hazardous” failure rate (unrevealed)
0.
48
pmh
“Safe” failure rate (revealed) 0 pmh
“Safe” failure rate (unrevealed) 0
System type B
Hardware Fault Tolerance 0
Diagnostic Coverage
>
60
%
PFD (hazardous failure) 2.1
x 10
-
3
Proof Test Interval Up to 1 year