LI-COR LI-870 Guide

Using the LI-870
CO2/H2O Analyzer

Using the LI-870
CO2/H2O Analyzer
LI-COR Biosciences
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The information in this document is subject to change without notice.
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Printing History
© Copyright 2019, LI-COR, Inc. All rights reserved
Publication number: 984-17878
Created on: Monday, February 22, 2021.
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iii
Notes on Safety
This LI-COR product has been designed to be safe when operated in the manner described in this manual. The safety of
this product cannot be assured if the product is used in any other way than is specified in this manual. The product is
intended to be used by qualified personnel. Read this entire manual before using the product.
Equipment markings:
The product is marked with this symbol when it is necessary for you to refer to the manual or
accompanying documents in order to protect against injury or damage to the product.
The product is marked with this symbol when a hazardous voltage may be present.
The product is marked with this symbol if a Chassis Ground connection is required.
The product is marked with this symbol to indicate that a direct current (DC) power supply is
required.
WARNING Warnings must be followed carefully to avoid bodily injury.
CAUTION Cautions must be observed to avoid damage to your equipment.
Manual markings:
Warning Warnings must be followed carefully to avoid bodily injury.
Caution Cautions must be observed to avoid damage to your equipment.
Note Notes contain important information and useful tips on the operation of your equipment.
CE Marking:
This product is a CE-marked product. For conformity information, contact LI-COR Support at [e-mail].
Outside of the U.S., contact your local sales office or distributor.
California Proposition 65 Warning
WARNING: This product contains chemicals known to the State of California to cause cancer and birth defects or other
reproductive harm.
Federal Communications Commission Radio Interference Statement
WARNING: This equipment generates, uses, and can radiate radio frequency energy and if not installed in accordance
with the instruction manual, may cause interference to radio communications. It has been tested and found to comply
with the limits for a Class A computing device pursuant to Subpart J of Part 15 of FCC rules, which are designed to
provide a reasonable protection against such interference when operated in a commercial environment. Operation of this
equipment in a residential area is likely to cause interference in which case the user, at his own expense, will be required
to take whatever measures may be required to correct the interference.

Waste Electronic and Electrical Equipment (WEEE) Notice
This symbol indicates that the product is to be collected separately from unsorted municipal waste. The fol-
lowing applies to users in European countries: This product is designated for separate collection at an
appropriate collection point. Do not dispose of as household waste. For more information, contact your
local distributor or the local authorities in charge of waste management.
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Contents
Section 1. Overview of the LI-870
What's what 1-1
LI-870 CO2/H2O Analyzer 1-1
LI-870 cable and tube assembly 1-2
Shoulder strap 1-2
Split ring assembly 1-2
Spares kit 1-3
Software 1-3
Section 2. Using the LI-870
Connecting the cable assembly 2-1
Powering the analyzer and making measurements 2-3
Identifying the LI-870 serial number 2-3
Storing the LI-870 2-5
Section 3. Troubleshooting
Smart Chamber or LI-8250 software not recognizing LI-870 3-1
Unable to Zero or Span the Instrument 3-2
Instrument Reports -50 ppm CO2 or Measurements Jump Around 3-2
Section 4. Maintenance
Cleaning the optical bench 4-1
Connecting to LI-870 for calibration 4-4
User calibration 4-5
Setting the H2O zero and spans 4-6
Setting the CO2 zero 4-6
Setting the primary CO2 span 4-7
Setting the secondary CO2 span 4-8
Recovering from a bad zero or span 4-8
Appendix A. Specifications

General A-1
CO2 Measurements A-1
H2O Measurements A-1
Appendix B. Equations summary
Appendix C. Warranty
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Section 1.
Overview of the LI-870
The LI-870 is a CO2/H2O Gas Analyzer that is designed for use with the Smart
Chamber and LI-8250 Multiplexer in soil gas flux systems. This document provides
basic operating instructions for the LI-870. Refer to the Smart Chamber and LI-
8250 manuals for additional information.
What's what
If you have just taken delivery of your LI-870, check your packing list to ensure the
following items have been included.
LI-870 CO2/H2O Analyzer
Part number:
870-01.
The LI-870 is a portable gas analyzer designed for use with the Smart Chamber or
LI-8250 Multiplexer for soil CO2flux measurements.
1-1Using the LI-870 CO₂/H₂O Analyzer

Section 1. Overview of the LI-870
The LI-870 measures CO2in air at concentrations from 0 to 20,000 ppm using
non-dispersive infrared gas analysis technology. This technology is well-established
in other LI-COR products, including the widely-published LI-8100A Automated
Soil CO2Flux System, LI-830 and LI-850 CO2and CO2/H2O Gas Analyzers, and
LI-COR eddy covariance analyzers. Water vapor measurements are used in cor-
rections to report CO2concentrations with high accuracy. Power to the LI-870 is
supplied from the Smart Chamber or LI-8250 Multiplexer. The LI-870, in turn,
provides CO2data to the Smart Chamber or LI-8250 Multiplexer for storage and
processing.
LI-870 cable and tube assembly
Part number:
9982-010.
A 1.2 meter cable and tubing assembly is included with the LI-870 to connect the
LI-870 with the Smart Chamber or LI-8250 Multiplexer. This assembly includes:
lSealed USB-A to USB-B cable (part number 392-17654).
lSealed 2.5 × 5 mm IP68 power cable (part number9982-008).
lTwo lengths 1.2 meter 1/4" Bev-A-Line® tubing (part number 222-01824) with
quick-connect fittings (part numbers 300-07124 (male) and 300-07125
(female)).
The assembly components are zip tied in plastic conduit.
Shoulder strap
Part numbers:
604-18146
The shoulder strap is to carry the LI-870.
Split ring assembly
Part number
9882-019
The LI-870 ships with a split ring and standoff assembled for attaching the
shoulder strap. The rings are attached near the clasps of the case. Each assembly
consists of a machined standoff (part number 9882-019), screw (part number 122-
07715), split ring (part number 610-10353), and two washers (part number 167-
00154).
1-2 Using the LI-870 CO₂/H₂O Analyzer

Spares kit
Part number:
9982-020.
A spares kit is shipped with the LI-870 and contains the following.
Description Quantity Part Number
1/4" Bev-A-Line® IV Plastic Tubing (12 meters) 1 8150-250a
1/4" Quick-connect Straight Union 2 300-03123
Quick Connect Plug 0.165 with Hose Barb (Male) 1 300-07124
Quick Connect Plug 0.165 with Hose Barb (Female) 1 300-07125
Optical Bench Cleaning Kit 1 9980-066
USB-A to USB-B, Unsealed, 6 meter 1 392-06652
Software
The LI-870 can be calibrated using the LI-830/LI-850 user interface software, which
is available from the LI-COR support site at licor.com/830-850-support. Select soft-
ware, and find the installer appropriate for your operating system. This software is
available for both Windows® and macOS® operating systems and is used to cal-
ibrate your LI-870 and view live data.
aAdditional tubing can be repurchased as a 15 meter roll.
Section 1. Overview of the LI-870
1-3Spares kit

Section 1. Overview of the LI-870
1-4 Using the LI-870 CO₂/H₂O Analyzer

Section 2.
Using the LI-870
The basic operation of the LI-870 involves connecting the USB data cable, con-
necting the tubing, and connecting the power cable between the LI-870 and Smart
Chamber or LI-8250 Multiplexer, as described here.
Connecting the cable assembly
Connecting the LI-870 to the Smart Chamber or LI-8250 Multiplexer is simple,
only requiring a few steps.
First, attach each end of the cable assembly to the LI-870. The USB-B end of the
USB-A to USB-B cable is attached to the LI-870, while the USB-A end is attached to
the Smart Chamber or LI-8250.
Note: Only use the supplied USB-A to USB-B cable from the LI-870 to cable
assembly (part number 9982-010).
Next, attach the cable assembly to the Smart Chamber or LI-8250. Connect the
steel quick connect fittings for the air tubing, and thread the power cable on to the
power-in and power-out connectors on each panel. Tighten snugly to ensure a
2-1Using the LI-870 CO₂/H₂O Analyzer

Section 2. Using the LI-870
water-tight seal. Follow the detailed instructions in the Smart Chamber or LI-8250
instruction manual for additional details.
Warning: The power output is 10-17 VDC with a center positive pin .
The output has a 2 amp maximum and is designed to only power the LI-870 CO2/H2O
Analyzer Accessory. Only use the power cable supplied with the LI-870 cable assembly
(P/N 9982-010), and do not attempt to power any other devices with the Smart Cham-
ber or LI-8250. Drawing a current in excess of 2 amps will trip the self-resetting
breaker. If you trip the self-resetting breaker, you will need to wait for a few minutes
before attempting to re-power the LI-870.
2-2 Using the LI-870 CO₂/H₂O Analyzer

Powering the analyzer and making measurements
After connecting the power cable, you should power on your Smart Chamber or
LI-8250 and launch the user interface software. Power to the LI-870 is supplied dir-
ectly from the Smart Chamber or LI-8250.
Identifying the LI-870 serial number
In the Settings page of the Smart Chamber or LI-8250 interface, you will need to
connect to your LI-870 using the serial number. The label is on the bottom of the
case.
Warm up time
The LI-870 will boot up as soon as power is supplied from the chamber. The
optical bench should be allowed to warm up prior to taking measurements. The LI-
870 optical bench is temperature- and pressure-controlled, so a sudden influx of
ambient air into an optical bench that has not been allowed to warm up and sta-
bilize will likely produce noisy data. For this reason, it is critical that your analyzer
is allowed to warm up prior to taking measurements. In most cases, 10 to 15
minutes of warm up time will allow the optical bench to stabilize, but warmup
time depends largely on ambient temperature.
Section 2. Using the LI-870
2-3Powering the analyzer and making measurements

Section 2. Using the LI-870
In the Smart Chamber and LI-8250 interface, you can see when your LI-870 optical
bench has stabilized when the dot in the upper-left portion of any screen by the
time stamp is green. If the bench is not stabilized, this dot will be red.
You can also visualize the optical bench temperature and pressure from the Home
Page of the Smart Chamber or LI-8250 interface to assess whether they have sta-
bilized. After connecting to the Smart Chamber or LI-8250, from the Home Page,
select Click to Set. In the Select a variable... window that opens, open the LI-870
list, and you can select Cell Temperature and Cell Pressure.
These variables will now be in the grid on the Home Page. Click them again to
graph the values live.
2-4 Using the LI-870 CO₂/H₂O Analyzer

The axes auto-scale, so pay close attention to the axis labels to assess stability. In the
example graph above, the bench temperature, for example, is stabilized within
roughly ± 0.1 °C from the median value/middle of the graph. Once the values have
stabilized like this, you can begin taking measurements following the instructions
in the Smart Chamber or LI-8250 manual.
Storing the LI-870
The post-purge function of the Smart Chamber is designed to allow for ambient air
to flush CO2- and water vapor-rich air from the cable assembly tubing and analyzer
after each measurement. When you are performing your last measurement(s) of
the season, or when you return to the lab or desk after taking your last meas-
urements, you should perform a measurement or two with the Smart Chamber to
allow dry ambient air to flow through your chamber. This will help to remove
humidity before storage.
Note: For more information on post-purge, consult the Smart Chamber manual
or find resources online at licor.com/env/support.
The LI-870 should be stored in non-condensing conditions. If the instrument is
stored in high humidity or moderate humidity for a long time while powered off,
some optical components may temporarily become saturated with humidity. If this
occurs, the instrument may need to run for several days before readings return to
normal. If possible, store the instrument in an air conditioned environment.
Section 2. Using the LI-870
2-5Storing the LI-870

Section 2. Using the LI-870
2-6 Using the LI-870 CO₂/H₂O Analyzer

Section 3.
Troubleshooting
In this section, we describe how to identify some potential problems with the LI-
870 and how to resolve them. If you can't find a solution here, if you need further
assistance performing maintenance, or if you have other questions, contact your
local distributor or LI-COR technical support for more help.
Smart Chamber or LI-8250 software not recognizing LI-870
Power is supplied from the Smart Chamber or LI-8250, and assuming your con-
nection is completed correctly, the gas analyzer is always powered on when the
Smart Chamber or LI-8250 is powered on. The Smart Chamber or LI-8250 will
automatically recognize your device with no further steps needed. Simply expand
the LI-870 drop-down in the Connections menu of the Measurement Settings page
of the Smart Chamber or LI-8250 software, select your instrument serial number,
and press Update.
If you open the drop-down menu and your instrument does not appear,
lIs your power cable fully connected to both devices? Make sure the cable is fully
inserted and the threaded nut is snugly fastened.
lIs your USB cable fully connected to both devices? Ensure that the connectors
on both sealed cables are clipped to the prongs on each device.
If your cables are fully connected but you still cannot identify your device, you can
open your device to see if power is being supplied. Next to the connection panel
inside the case, a red LED light will be blinking if power is being supplied.
3-1Using the LI-870 CO₂/H₂O Analyzer

Section 3. Troubleshooting
Note: Do not open the LI-870 enclosure in the field. This can cause the tem-
perature and pressure of the optics to become destabilized. More importantly, this
can allow dust and debris into your analyzer. If possible, you should confirm
whether your analyzer is working properly and troubleshoot any issues before tak-
ing it out to the field.
If your Smart Chamber or LI-8250 is on and your cables are properly connected,
the light should be blinking. If it is not blinking, something could be wrong with
your power cable, the chamber power-out connector, analyzer power-in connector,
or other electronics inside the case. Check for dust and debris in the connectors
and for damage to the cable itself. For power-related issues, it is recommended that
you call LI-COR technical support for further instructions.
If the light is blinking but you still cannot identify your device through the Smart
Chamber or LI-8250 software, check your USB cable for damage. Is there dust or
debris in the cable heads or the connectors? Try refreshing the interface software,
clearing your browser cache, and rebooting your Smart Chamber or LI-8250. If you
still cannot connect, contact LI-COR technical support.
Unable to Zero or Span the Instrument
Is there dirt in the optics? If the optical cell becomes contaminated, the instrument
will drift in either the zero or span. See Troubleshooting on the previous page for
details on cleaning your optical bench.
Instrument Reports -50 ppm CO2or Measurements Jump Around
If the instrument measures -50 ppm or the measurements are going between neg-
ative and positive values, or just simply not making any sense, the optical source
may have failed or be in the midst of failure. Contact technical support for addi-
tional troubleshooting help.
3-2 Using the LI-870 CO₂/H₂O Analyzer