2
95-8676
3.1
DETECTABLE GASES
The model PIRECL detector is capable of detecting
CO
2
(Carbon Dioxide).
OUTPUTS
Standard
The standard version provides an isolated/non-isolated
4-20 mA current loop for connection to analog input
devices.
Optional Relays
An optional relay output board providing two
programmable alarm relay outputs and one fault
relay output can be factory installed with the standard
version. All relays are sealed and provide form C (NO/
NC) contacts. The high and low alarm relay settings
are programmable and can be set for latching or non-
latching operation. The low alarm cannot be set above
the high alarm threshold. Alarm configuration can be
done with the HART or MODBUS interface.
The onboard tri-color LED indicates a LOW alarm
condition via a flashing red color, and a HIGH alarm
condition via a steady red color. The Eclipse internal
magnetic switch or HART Field Communicator can be
used to reset latched alarms. A short-duration magnetic
switch activation of 1 second will reset latched alarms.
Holding the magnetic switch closed for 2 seconds will
start the calibration sequence. The external calibration
line will not reset latched alarm relays.
When the optional relay output board is specified, the
PIRECL’s approval rating is Ex d only.
NOTE
Refer to “Alarm Relays” in the Specifications
section of this manual for important information
regarding alarm relays.
DATA LOGGING CAPABILITY
Non-volatile memory is provided to save the 10 most
recent calibrations, alarm/fault events, and minimum/
maximum operating temperature history. An hour meter
(running operational hours since startup) is provided to
record operating service time and to give an indication
of the relative time between events. This information is
accessible using HART or MODBUS communication.
OPTIONAL THIRD PARTY ADDRESSABLE MODULES
The PIRECL is electrically compatible with third party
addressable modules, provided the module fits within
the PIRECL wiring compartment. Whenever a third party
addressable module is installed, the PIRECL’s Ex e rating
is void, and only the Ex d rating is valid. Installation of
a third party addressable module requires a specially
labeled PIRECL model to ensure valid product approvals.
SIGNAL PROCESSING
ELECTRONICS
GAS
CONCENTRATION
(%/Volume or PPM)
IR SOURCE
IR TRANSPARENT
WINDOW
OPTICAL
BEAM SPLITTER
MEASUREMENT
SIGNAL DETECTOR
REFERENCE
SIGNAL DETECTOR
OPTICAL
FILTERS
PERMEABLE
GAS CELL
SAPPHIRE
MIRROR
Figure 1—Measurement Scheme for Infrared Gas Detector
