Detcon IR-700 SIL 2 Safety Manual - Manual (Page 2)

3 DESIGN
The Model IR-700 is a NDIR non-dispersive infrared type combustible hydrocarbon gas detector that is classified as a
Type B smart device according to IEC61508. The IR-700 sensor provides a 4-20 mA output that is proportional to
combustible gas vapor concentrations in the ranges of 0-100% LEL The IR-700 contains extensive self-diagnostics and
is programmed to send the current output to a specified failure state (0 mA) upon internal detection of a failure. A Modbus
RS485 serial output is available in addition to the analog signal output. The Safety Certification for the IR-700 Gas
Detector only covers the use of the standard analog 4-20 mA output.
Safety-Certification of the IR-700 includes the 4-20 mA output. The RS-485 Modbus signal output is not part of the
SIL Certification.
Note: Proper analog signal loop resistance must be installed as documented in the instruction manual to enable proper
4-20 mA signal function. The end user must perform zero and span calibrations after any significant configuration
changes or repair events. These include: restore defaults, change of range, replacing plug-in NDIR sensor, and replacing
ITM module.
4 VALID INPUT RANGE
IR-700 fault annunciation is provided on the 4-20mA signal output loop by signaling to 0mA current output level for at
least 5 seconds. The receiving device must be programmed to indicate an out-of-range condition when current levels reach
overcurrent (>21.5 mA) or undercurrent (< 1.3 mA).
Note: The IR-700 analog signal output is not safety-rated during detector warm-up, configuration mode, calibration
mode, and during signal output loop testing. Alternative means should be used at the jobsite to ensure facility safety
during these activities.
5 DIAGNOSTIC RESPONSE TIME
The IR-700 will perform all critical diagnostic functions within 2 hours. This is the worst case diagnostic detection time.
6 CERTIFICATION
The IR-700 Safety-Certified version is certified by exida® to IEC 61508 for single input use in low and high demand, SIL
2 Safety Instrumented Systems. The IR-700 sensor is SIL2 certified as an individual component, but it can be used as
part of a larger Safety Instrumented Systems as long as it is applied per the guidelines of this Safety Manual.
The IR-700 is SIL2 certified per IEC 61508-2010 with an HFT=0.
The revision levels of this SIL 2 certified IR-700 sensor is noted as Main PCB Rev 1, Amplifier PCB Rev 1, and
Firmware V8.01N.
7 SAFETY – CERTIFIED PRODUCT IDENTIFICATION
The model number printed on the label will include the character “S” in the model number string, indicating exida®
approval for SIL 2 standard. Example: Model IR-700 S.
8 CONSTRAINTS
The safety function of the Detcon Model IR-700 Combustible Gas Sensor is limited by the following constraints:
- Shall not be used in continuous mode applications
- The maximum load on the 4-20mA output of the IR-700 is 1KΩ with 24VDC input power and 500Ω with 12VDC
input power. The minimum load on the 4-20mA output is 10Ω.