Det-Tronics PIRECL Infrared Carbon Dioxide Gas Detector PointWatch Eclipse - Manual (Page 3)

Important
Be sure to read and understand the entire
instruction manual before installing or operating
the gas detection system. This product is intended
to provide early warning of the presence of carbon
dioxide gas. Proper device installation, operation,
and maintenance is required to ensure safe and
effective operation. If this equipment is used
in a manner not specified in this manual, safety
protection may be impaired.
ApplicAtion
NoTe
The normal outdoor level of Co
2
is approximately
370 ppm. Indoor levels are typically less than
1000 ppm, but can be higher depending on the
efficiency of the ventilation system. Keep this in
mind when varied Co
2
levels are detected within
a building.
The PointWatch Eclipse ® Model PIRECL CO
2
Detector is a diffusion-based, point-type infrared
gas detector that provides continuous monitoring
of Carbon Dioxide (CO
2
) gas concentrations in the
range of 0-2%/volume (0-20000 ppm).
Two basic configurations are available:
• 4-20 mA output with HART communication protocol
and RS-485 MODBUS communications.
• 4-20 mA output with HART communication protocol
and RS-485 MODBUS communications, with two
alarm relays and one fault relay.
All units are powered from 24 Vdc, and are furnished with
an onboard "status indication" LED, an internal magnetic
calibration switch and an external calibration line for use
with the optional PIRTB remote calibration termination
box.
The Eclipse CO
2
detector is ideal for use in harsh
outdoor environments and is certified for use in Class I,
Division 1 (CSA), and Zone 1 (ATEX/IECEx) hazardous
areas. It can be used as a stand-alone detector, or as
part of a larger facility protection system.
operAtion overview
Theory of operaTIon
Carbon dioxide gas is diffused through the weather
baffle assembly into the internal measurement chamber,
which is illuminated by an infrared (IR) source. As
the IR passes through the gas within the chamber,
certain IR wavelengths are absorbed by the gas,
while other IR wavelengths are not. The amount of IR
absorption is determined by the concentration of the
carbon dioxide gas. A pair of optical detectors and
associated electronics measure the absorption. The
change in intensity of the absorbed light (active signal)
is measured relative to the intensity of light at a non-
absorbed wavelength (reference signal). See Figure 1.
The microprocessor computes the gas concentration
and converts the value into a 4 to 20 milliampere current
output or digital process variable signal, which is then
communicated to external control and annunciation
systems.
InSTrUCTIonS
Infrared Carbon Dioxide Gas Detector
PointWatch Eclipse ®
Model PIRECL
2.1 © Detector electronics Corporation 2012 Rev: 9/12 95-8676