LI-820 OEM CO2 Gas Analyser Brochure (PDF) - John Morris Scientific

LI-820 CO 2 Analyzer
For OEM Applications
Introducing the LI-820
Long recognized as a market leader in high
quality, portable infrared gas analyzers for
environmental research, LI-COR, Inc. now
introduces the LI-820 CO 2 Analyzer, a low
cost, low maintenance CO 2 analyzer for OEM
applications.
Choose Your Measurement
Range
The LI-820 is a single path, dual wavelength,
non-dispersive infrared (NDIR) gas analyzer
with ± 1 ppm resolution. This compact,
lightweight analyzer features interchangeable
optical benches; your choice of a 5.5" (14 cm)
bench with CO 2 measurement ranges of 0-
1000 or 0-2000 ppm, and a 2" (5 cm) bench
with measurement ranges of 0-5000 or 0-
20000 ppm.
Sophisticated Measurement
Technology
A built-in pressure sensor and a thermostatically
controlled optical path provide excellent
stability over time, temperature and pressure
changes. This reduces the need for frequent
zero and span adjustments.
Choose Your Application
The LI-820 is well suited for industrial and
other continuous CO 2 monitoring applications.
High/low alarms can be used to control CO 2
levels or to notify operators of abnormally
high or low CO 2 conditions. Activated alarms
are also indicated by LED lights on the
instrument top panel. The LI-820 is perfect for
incorporating into larger complex or multi-gas
instruments requiring a reliable OEM CO 2
analyzer.
Multiple Data Outputs
For complete and easy integration of the
LI-820 into other equipment controls for OEM
applications, the LI-820 features a communication
protocol based on a subset of the
eXtensible Markup Language (XML). XML
is a simple text-based language allowing
communication with the LI-820 using simple
text strings sent bi-directionally between a data
acquisition system and the LI-820 over the RS-
232 port. As an example, sending this
command:
?
instructs the LI-820 to send the most recent set
of data values. In this manner, the LI-820 can
be polled for data at user-defined intervals,
globally reconfigured, or configured to
perform automatic calibration routines.
A choice of parameters (CO 2 , cell pressure, or
cell temperature) can be output as linearized
voltage or current signals. In addition, 0-5V
alarm relay outputs can be connected to
audible alarms, relay switches, automatic
dialers, pumps, or valves in industrial settings.
The LI-820 also comes with Windows®compatible
interface software for instrument
configuration, control, data collection, and
display.
Simple Maintenance
The optical bench can be easily cleaned with
the cleaning kit provided; simply remove the
source and detector housings and swab out the
optical path. This reduces down-time due to
contamination, and eliminates the need for
factory recalibration.
●
●
●
●
●
●
●
●
Safety monitoring
Leak detectors
Indoor air quality
TOC analyzers
Greenhouse control systems
Growth chambers
Fruit storage
Meteorological studies

LI-820 Operating Principle
The LI-820 analyzer is a single beam, dual
wavelength NDIR sensor. The CO 2 measurement
is a function of the absorption of IR
energy as it travels through the optical path.
Source
Gold Plated
Parabolic Reflector
Gold Plated
Optical Path
Pressure Transducer
Filters
3.95 & 4.26 µm
Detector
The IR source emits radiation into the optical
path, where CO 2 absorbs photons of a certain
wavelength. The CO 2 sampling channel uses
an optical filter centered at 4.26 micrometers,
corresponding to the absorption band for CO 2 ,
while the reference channel uses a nonabsorbing
band at 3.95 micrometers. The
detector measures the absorption of the
infrared beam passing through the optical
path; the ratio of the sample and reference
signals indicates the amount of light absorption
by CO 2 , and thus, the gas concentration.
Thermistor
Ribbon Cable
Connector
Gas Inlet
Heating Element
Broad Band IR Source
Gas Outlet
Heating Element
14 cm and 5 cm
optical benches
Thermistor
Interchangeable optical benches swap out
easily by means of two source connectors on
the main circuit board; swapping the benches
takes only a few minutes.
Ordering Information
LI-820 CO 2 Analyzer:
Includes LI-820 CO 2 Analyzer with choice of 5.5” (14 cm) or 2” (5 cm) optical bench, spare parts kit, 2 disposable air filters, cleaning kit, Windows®
communications software, and a 9-pin RS-232 communications cable. A power source is required.
800-401 AC Power Supply (110 VAC):
18 VDC output, 800 mA, for indoor use only. The AC power supply is required if the LI-820 will not be wired directly to an external source. See
Power Requirements in the specifications.
Specifications
Measurement Range: 0 – 1000 ppm, 0 – 2000 ppm with 14 cm optical bench
0 – 5000 ppm, 0 – 20000 ppm with 5 cm optical bench
Measurement Principle: Non-Dispersive Infrared
Accuracy: