Det-Tronics OPECL Infrared Hydrocarbon Gas Detector SAFETY MANUAL - Manual (Page 2)

1.2 95-8665 2
DESIGN
The Model OPECL Open Path Eclipse Gas Detector is
an infrared hydrocarbon gas detector that is classified
as Type B smart device according to IEC61508. It
provides an isolated 4-wire 4-20 mA output that is
proportional to hydrocarbon vapor concentrations from
0-5 LFL-meters. The OPECL contains extensive self-
diagnostics and is programmed to send the current
output to a specified failure state upon internal detection
of a failure (see OPECL instruction manual for fault
output level details). Optional Alarm and Fault relay
contact outputs are available in addition to the analog
signal output, and can be programmed in the field by
the user. The Safety Certification for the OPECL Open
Path Eclipse Gas Detector includes both the standard
version with analog output only and the version with
optional relay outputs. The relay output and analog
output are not to be used in combination for the safety
function.
Safety-Certification of the OPECL Open Path Eclipse
includes:
• the 4-20 mA output
• the Fault and High Alarm Relay outputs
RS-485 Modbus signal output is not part of the SIL
certification.
The HART communication protocol is non-interfering
and is to be used for diagnostics within the SIL 2
safety loop in the Safety operation mode. Diagnostics
are defined as read only information. Local HART
communication with the OPECL IR Gas Detector via the
onboard intrinsically-safe communication port using a
handheld HART field communicator, or AMS program
connected to the 4-20 mA output, is acceptable. Proper
analog signal loop resistance must be installed as
documented in the instruction manual to enable local
HART communication.
VALID INPUT RANGE
OPECL fault annunciation is provided on the 4-20 mA
signal output loop by signaling to a specific mA current
output level. The receiving device must be programmed
to indicate a fault condition when current levels reach
overcurrent (> 20.5 mA) or undercurrent (< 3.8 mA).
NOTE
The OPECL analog signal and relay outputs
are not safety-rated during detector warm-up,
alignment mode, calibration mode, or during
signal output loop testing. Alternative means
should be used at the job site to ensure facility
safety during these activities.
DIAGNOSTIC RESPONSE TIME
The OPECL Infrared Gas Detector will perform all
critical diagnostic functions within 58 minutes, worst
case diagnostic detection time.
CERTIFICATION
The OPECL Safety-Certified version is certified by
exida ® to IEC61508 for single input use in low demand,
SIL 2 Safety Instrumented Systems.
SAFETY-CERTIFIED PRODUCT IDENTIFICATION
The model number printed on the label will include the
character “T” in the model number string “Approval
Agency Type” section, indicating exida ® approval for
SIL 2 standard. Example: Model OPECLS2M00T1S.
INSTALLATION
NOTE
For complete information regarding performance,
installation, operation, maintenance and
specifications of Model OPECL, refer to
instruction manual 95-8556.
No special or additional detector installation
requirements exist above and beyond the standard
installation practices documented in the Model OPECL
instruction manual.
The operating temperature range for the Safety Certified
OPECL is –40°C to +60°C. Other environmental
operating specifications are applicable as published in
the general specifications section in the Model OPECL
instruction manual.
The OPECL operating power distribution system should
be designed and installed so the terminal voltage does
not drop below 18 Vdc when measured at any specific
location. The maximum current limit per transmitter or
receiver must be less than 2 amperes. The external
system providing power to the OPECL must have over-
voltage protection that ensures supply voltage does not
exceed 30 Vdc.