LI-COR LI-7820 User manual

LI-7820 N2O/H2O
Trace Gas Analyzer
Instruction Manual

LI-7820 N2O/H2O
Trace Gas Analyzer
Instruction Manual
LI-COR Biosciences
4647 Superior Street
Lincoln, Nebraska 68504
Phone: [phone]
Toll free: 800-447-3576 (U.S. and Canada)
[e-mail]
Regional Offices
LI-COR Biosciences GmbH
Siemensstraße 25A
61352 Bad Homburg
Germany
Phone: [phone]
[e-mail]
LI-COR Biosciences UK Ltd.
St. John’s Innovation Centre
Cowley Road
Cambridge
CB4 0WS
United Kingdom
Phone: [phone]
[e-mail]
LI-COR Distributor Network:
www.licor.com/env/distributors

Notice
The information in this document is subject to change without notice.
LI-COR MAKES NO WARRANTY OF ANY KIND WITH REGARD TO THIS MATERIAL, INCLUDING BUT NOT
LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
LI-COR shall not be held liable for errors contained herein or for incidental or consequential damages in connection with
the furnishing, performance, or use of this material.
This document contains proprietary information, which is protected by copyright. All rights are reserved. No part of this
document may be photocopied, reproduced, or translated to another language without prior written consent of LI-COR,
Inc.
Microsoft, Windows, and Excel are registered trademarks of the Microsoft Corporation. Wi-Fi is a trademark of the Wi-Fi
Alliance. Swagelok® is a registered trademark of the Swagelok Company. All other trademarks and registered trademarks
are property of their respective owners.
This product is protected by U.S. patents 8,659,758, 8,665,442, 8,885,167, 9,116,047, 9,194,742, 9,304,080, 9,581,492,
9,678,003, 9,759,654, 9,759,655, 9,989,729, and 10,060,942. Additional patents pending in the U.S. and other countries.
Printing History
© Copyright 2020, LI-COR, Inc. All rights reserved.
Publication Number: 984-19432
Created on: Wednesday, March 17, 2021.
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.
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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 can expose you to chemicals including Nickel, which is known to the State of
California to cause cancer. For more information go to www.P65Warnings.ca.gov.
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.
Wi-Fi Warning
When powered on for the first time, this device will broadcast a wireless local area network (WLAN) signal. The use of
WLAN is restricted in some regions and countries, and the illegal use of WLAN may be punishable under these reg-
ulations. Check your local regulations to determine if WLAN is permitted.
If WLAN is not permitted in your area, it is your responsibility to disable the WLAN signal. LI-COR, Inc. cannot be held
liable for any problems arising from the use of WLAN in any countries or regions where it is not permitted. Legal pen-
alties may result from failing to disable or re-enabling the wireless network where it is not permitted, modifying or altering
the product, or removing the certification labels from the product.
Instructions for disabling the WLAN signal are provided in this manual.

Preface
This document provides basic operating instructions for the LI-7820 N2O/H2O
Trace Gas Analyzer.
We have made every effort to ensure that this document accurately represents
the instrument. As with any software-dependent instrument, development con-
tinues after the documentation goes to press. As a result, small inconsistencies
between the documentation and the instrument may be present.
Updates to this document, as well as application notes, technical literature,
videos that support the product, and software updates, will be available from
licor.com/env/support (search for LI-7820).
We appreciate feedback on this manual. Send your comments to
envfeedb[email protected].
For technical support with the product, go to licor.com/env/support or email
[e-mail].
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Contents
Preface iv
Section 1. Introduction to the LI-7820
What's what 1-1
Gas analyzer 1-1
Rechargeable batteries 1-3
Universal power adapter 1-3
Ethernet cable 1-4
Accessory kit 1-5
Optional accessories 1-5
Auxiliary power cable 1-5
Backpack kit 1-5
Section 2. Getting started
Powering on the instrument 2-1
Power options 2-2
Universal power adapter 2-2
Rechargeable batteries 2-2
External power source 2-3
Connecting with the instrument 2-4
Connecting over wireless 2-5
Connecting over a wired network 2-6
Enabling and disabling Wi-Fi 2-7
Instrument display 2-8
Status codes 2-9
Powering off the instrument 2-10
Storing the instrument 2-11
Shipping the instrument 2-11
Section 3. Applications of the LI-7820
Flow schematic 3-1
Soil gas flux measurements 3-2
Connecting the air inlet and outlet 3-2
Plumbing a subsample 3-3
Retrieving data from the instrument 3-4

Downloading a data file 3-4
Components of the data file 3-5
Installing the instrument in a rack mount 3-7
Section 4. Software overview
Home page 4-1
Indicators and buttons 4-1
Remarks 4-2
Graphs 4-3
Settings 4-4
Software 4-4
Time 4-6
Network 4-7
Wi-Fi 4-8
LI-8100/A 4-9
Calibration 4-10
Diagnostics 4-11
Power 4-11
Performance status indicators 4-11
Diagnostic log 4-12
Performance monitor 4-12
Operating information 4-13
Layouts 4-14
Thresholds 4-15
Export 4-15
Section 5. Troubleshooting
Connection problems 5-1
Request to connect to instrument network rejected by Android OS 5-1
Unable to connect with the instrument over a wired connection 5-1
Unable to connect with the instrument over a wireless connection 5-3
Measurement problems 5-4
Readings drift or step change unexpectedly 5-4
Pressure readings are questionable or unstable 5-4
Gas density measurements appear to have oscillations 5-4
Interface issues 5-4
The interface is in a language that I don't understand 5-5
Graphed data overlaps in time or has gaps 5-5
Status and warning messages 5-5
Code 128 triggered 5-6
Section 6. Maintenance
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Instrument calibration 6-1
Setting the N2O span and zero 6-2
Recovering from a bad calibration 6-3
Replacing the air inlet filter 6-4
Replacing the purge dry-down chemical 6-5
Software updates 6-7
Section 7. Communication with the MQTT protocol
Terminology 7-1
Basic commands in a terminal program 7-2
Streaming data into the interface 7-3
Setting the zero calibration 7-4
Setting the span calibration 7-5
Rebooting the instrument 7-6
Powering off the instrument 7-6
Basic commands with a Python script 7-7
Configuring paho-mqtt in Windows 7-7
Configuring paho-mqtt in Mac or Linux 7-7
Streaming data into the Terminal Program 7-8
Downloading data in a date and time range 7-9
Additional commands 7-10
Appendix A. Measurement overview
Appendix B. Additional safety information
Appendix C. Specifications
Appendix D. Warranty
Appendix E. Index

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Section 1.
Introduction to the LI-7820
The LI-7820 N2O/H2O Trace Gas Analyzer is a high-precision, high-stability, laser-
based gas analyzer that uses Optical Feedback — Cavity-Enhanced Absorption Spec-
troscopy (OF-CEAS) to measure gases in air. OF-CEAS is a well-established spec-
troscopic technique that is described in published literature. The analyzer reports
and stores in its internal memory N2O dry mole fractions in air corrected for both
the spectroscopic interferences and dilution due to H2O. See Measurement overview
on pageA-1 for a brief summary of OF-CEAS.
What's what
If you have just taken delivery of the instrument, check your packing list to be sure
you received everything that you ordered. The LI-7820 includes some or all of the
following components.
Gas analyzer
The gas analyzer is in a gray enclosure. It is designed for indoor and outdoor use
but it is not waterproof.
1-1LI-7820 N₂O/H₂O Gas Analyzer

Section 1. Introduction to the LI-7820
The analyzer should not be allowed to sit in standing water, exposed to driving
rain, or deployed outdoors without weather protection. Use caution to avoid draw-
ing water into the analyzer air inlet! Although equipped with software protection
that disables the pump if a clog is detected (such as the filter becoming wet and
stopping air flow), if water is drawn into the inlet the instrument will have to be
repaired at the factory.
Power button
The power button is used to power the instrument on and off and enter and exit
sleep mode. It has an indicator light that will be illuminated when the instrument
is powered on and dark when it is powered off. Functions of the button are
described in Powering on the instrument on page2-1 and Powering off the instrument on
page2-10.
Power cable connector
The power cable connector on the instrument is compatible with the universal
power adapter (part number 9968-232) and the optional DC power cable (part num-
ber 9968-242). See Power options on page2-2.
Warning: Use the safety-approved power cord supplied with the instrument. The instru-
ment power supply is equipped with a 3-wire grounding plug. This plug will only fit into
a grounded outlet. Do not defeat the purpose of the grounding-type plug. Do not place
the instrument where the power cord will be walked on or exposed to water or chem-
ical spills.
Avertissement: Utilisez le cordon d'alimentation approuvé pour la sécurité fourni avec
l’instrument. L'alimentation de l'instrument est équipée d’une fiche de terre à 3 fils.
Cette fiche ne rentrera que dans une prise de terre. N’allez pas à l’envers de la fonction
de la fiche de mise à la terre. Ne placez pas l’instrument où le cordon d'alimentation
sera piétiné ou exposé à l'eau ou aux déversements de produits chimiques.
Network cable connector
The network cable connector is compatible with standard RJ-45 Ethernet cables.
Air inlet
The instrument draws air in through the inlet using the internal pump. The inlet
connector is a compression fitting, which is compatible with ¼" outside diameter
1-2 LI-7820 N₂O/H₂O Gas Analyzer

tubes. Additional nuts and ferrule sets are include in the accessories kit.
Warning: Do not exceed the maximum absolute pressure rating of 110 kPa.
Advertissement: Ne dépassez pas la pression nominale absolue maximale de 110 kPa.
Air outlet
The instrument exhausts sample air through the outlet. Do not substantially restrict
or apply a vacuum to the outlet.
Rechargeable batteries
Part Number
442-11807
Two batteries are provided with the instrument. We recommend leaving at least
one battery in the instrument when you are using it. The batteries are 14.4 V lith-
ium ion battery packs with 6.8 amp-hour capacity. Two batteries can provide up to
8 hours of operation under most conditions. Batteries are shipped in a partially dis-
charged state. They should be fully charged prior to the first use. Storing the bat-
teries in a discharged state can result in damage to the batteries. Batteries that are
installed in the instrument will be charged when the instrument is powered
though the universal power adapter.
Warning: Lithium ion batteries may cause environmental damage or damage to human
health if they are disposed of improperly. Do not dispose of the batteries in unsorted
municipal waste or an incinerator. Many localities have battery recycling facilities that
will accept lithium ion batteries. Check your local regulations to determine how to
safely dispose of the batteries.
Advertissment: Les batteries lithium ion peuvent causer des dommages à
l'environnement ou endommager la santé humaine si l’on se débarrasse d’elles de man-
ière inappropriée. Ne vous débarrassez pas des batteries dans des déchets municipaux
non triés ou dans un incinérateur. Plusieurs localités ont des installations de recyclage
de batteries qui accepteront les batteries lithium ion. Vérifiez vos réglementations loc-
ales pour déterminer comment se débarrasser des batteries en toute sécurité.
Universal power adapter
Part Number
9968-232
The universal power adapter is an AC-to-DC adapter that powers the instrument
and charges the batteries when it is plugged into an AC power outlet. The power
adapter provides 24 VDC (9.17 amps maximum; 220 watts maximum). It is
Section 1. Introduction to the LI-7820
1-3Rechargeable batteries

Section 1. Introduction to the LI-7820
compatible with 100 to 240 VAC, 50 to 60 Hz. The instrument will include one of
the cords listed in Table 1-1 below. The power adapter and cord are for indoor use;
they are not rated for outdoor deployment.
Description Part Number
For USA, Canada, Mexico, and Japan; NEMA 5-15; Type B 390-00787
For Europe, South America, and Asia; CEE 7/7; Type C 390-01486
For United Kingdom; Type G 390-03089
For Israel; SI32; Type H 390-03059
For Australia; Type I 390-03095
Table 1-1. Power cables for the power adapter.
Warning: Use the safety-approved power cord supplied with the instrument. The instru-
ment power supply is equipped with a 3-wire grounding plug. This plug will only fit into
a grounded outlet. Do not defeat the purpose of the grounding-type plug. Do not place
the instrument where the power cord will be walked on or exposed to water or chem-
ical spills.
Avertissement: Utilisez le cordon d'alimentation approuvé pour la sécurité fourni avec
l’instrument. L'alimentation de l'instrument est équipée d’une fiche de terre à 3 fils.
Cette fiche ne rentrera que dans une prise de terre. N’allez pas à l’envers de la fonction
de la fiche de mise à la terre. Ne placez pas l’instrument où le cordon d'alimentation
sera piétiné ou exposé à l'eau ou aux déversements de produits chimiques.
Ethernet cable
Part Number
616-06116
Network cable with RJ-45 connectors (Cat5e); to connect the instrument to a com-
puter or network. Length of 2.1 meters (7 feet).
Note: Do not use cables other than the one provided. Other cables may result in
improper electrical performance.
1-4 LI-7820 N₂O/H₂O Gas Analyzer

Accessory kit
Part Number
9978-195
The accessory kit includes some accessories and replacement components that may
be useful to you. Additional replacement parts are available from LI-COR or your
local distributor.
Description Quantity Part Number
Replacement dry-down chemical pack (17 grams each) 3 622-17627
Stainless Steel Screws ; M3×0.5; 8 mm 6 150-14419
O-ring; 27×1.5 mm 2 192-16956
O-ring; 22×2.5 mm 4 192-17345
Stainless Steel 1/4" Ferrule and Nut Set 5 300-15025
Filter support disks 2 9878-280
Filter pack; 2-micron (10 filters) 1 9978-234
Optional accessories
In addition to the items already mentioned, the analyzer may include the following
accessories.
Auxiliary power cable
Part Number
9968-242
This optional component allows you to power the instrument from an external DC
power supply, such as a deep cycle battery. It has a connector for the instrument
power connection and bare leads for a power source. Power requirements are given
in External power source on page2-3.
Backpack kit
Part Number
6578-380
The backpack kit is an optional accessory that can be used to carry the instrument.
It features a padded back and padded shoulder straps with a padded waist strap and
chest strap to help support the instrument as you carry it.
Section 1. Introduction to the LI-7820
1-5Accessory kit

Section 1. Introduction to the LI-7820
The analyzer is secured in the backpack with several straps. The bottom of the
instrument will be against your back. The tubes can face up or down. Use caution
with the backpack kit:
lClose the clasps and tighten the straps so that the instrument is secure.
lDo not block the vents or set the instrument in standing water.
lIf you are unable to lift the backpack kit comfortably or tighten the straps, con-
sider enlisting the help of a "strapping" assistant.
lClip the chest and waist straps. Tighten all of the straps snugly.
1-6 LI-7820 N₂O/H₂O Gas Analyzer

Section 2.
Getting started
This section provides basic operating instructions for the instrument.
Powering on the instrument
To power on the instrument, either install a battery and push the power button or
connect the instrument to an external power supply. The instrument will power on
any time power is supplied through the AC power adapter or the auxiliary power
cable. See Power options on the next page for more details.
If main power is lost, the instrument will run until the batteries are depleted and
then it will power off. When the main power is restored, the instrument will power
up and the batteries will resume charging (only if powered through the universal
power adapter). When powered by batteries only, you must press the power button
to turn on the instrument.
Upon powering on, the instrument will issue a series of status codes as it completes
the start up cycle. The pump will start running when the optical bench approaches
55 °C. If starting from room temperature, it will take about 20 minutes before you
can connect and another 10 or 15 minutes before it provides accurate meas-
urements. If the instrument is very cold, it will take longer to warm up.
The instrument cannot be powered on from afar. You can restart the instrument
through the software interface, but if you power it off through the software inter-
face or the power button, you must press the button or reconnect the main power
supply to turn it back on. See Powering off the instrument on page2-10 for additional
details.
2-1LI-7820 N₂O/H₂O Gas Analyzer

Section 2. Getting started
Power options
The instrument can be powered using the universal AC power adapter,
rechargeable batteries, or an external power source using the optional auxiliary
power cable. We recommend leaving one battery in the instrument when in use to
ensure proper shut down if main power is lost unexpectedly.
Universal power adapter
The universal power adapter is com-
patible with 100 to 240 VAC power
sources, both 50 and 60 Hz. It outputs
24 VDC to power the analyzer and
charge the batteries that are installed.
The instrument will power on when the
universal power adapter is connected to a
power source.
Rechargeable batteries
Two batteries can be installed behind the battery cover. When not using the AC
power adapter, a single battery is required to power the instrument. The instrument
supports hot-swapping, meaning that you can remove a partially depleted battery
and replace it with a charged one and measurements will not be disrupted — as
long as the instrument is powered by a charged battery or the AC power adapter.
The batteries are not user serviceable. If a battery exceeds a tem-
perature or load threshold, a non-resettable fuse will open, ren-
dering the battery non-functional. If the batteries become
excessively discharged in storage, the charger will supply a 3-
minute wake-up charge in an attempt to activate the elec-
tronics.
Charging batteries in the instrument
Batteries in the instrument are charged any time the instru-
ment is powered by the universal power adapter. The 10.5 to 33 VDC power ter-
minals (pins 3 and 4; Table 2-1 on page2-4) do not charge the batteries. The charge
status is given in the web interface, the instrument display, and on the battery.
2-2 LI-7820 N₂O/H₂O Gas Analyzer

Charging batteries with an external charger
The optional single-bay charger (part number 590-11830; Inspired Energy
CH7000A) can charge one battery at a time. To use the charger, plug it into a wall
socket and place a battery in the dock. The charger is compatible with 100 to 240
VAC power at 50 to 60 Hz. A blinking LED indicates charging; a solid green LED
indicates a full charge.
Note: An optional automobile adapter kit is available to charge the battery from
an automobile. Leave the automobile running when charging the battery to pre-
vent excessive discharge of the automobile battery.
Warning: Charge batteries only with a SMBUS compliant level 2 or 3 charger. Do not
heat above 80 °C. Do not open battery, dispose of in fire, or short circuit—may ignite,
explode, leak, or get hot, causing personal injury. Replace battery with same part num-
ber only. Use of another battery may present a risk of fire or explosion. Keep away from
children.
Avertissement: Ne rechargez les batteries qu’avec un chargeur conforme au SMBUS
niveau 2 ou 3. Ne chauffez pas au-dessus de 80 °C. Ne pas ouvrir la batterie, ni ne la
jeter au feu ou court-circuiter—elle peut mettre à feu, exploser, couler, ou s’échauffer,
causant des blessures personnelles. Remplacez les batteries seulement avec le même
numéro de pièce. L’utilisation d’une autre batterie peut presenter un risque, ou un incen-
die ou une explosion. A garder hors de portee des enfants.
External power source
Figure 2-1. The auxiliary power cable
has bare leads that connect to a power
supply.
You can power the instrument with any
10.5 to 33 VDC power source, such as a
deep-cycle marine battery with >20 amp-
hour capacity. The external power source
should be connected with the auxiliary
power cable (optional; part number 9968-
242). Attach both red leads to positive (+)
and both black leads to negative (-).
Section 2. Getting started
2-3External power source

Section 2. Getting started
Pin Assignment Color Description
1 Power (+) n/a 24 VDC; 6 Amps from the LI-COR power adapter.
These pins, when paired to ground (2 and 6), will
power the device and charge the batteries. Not
powered through the auxiliary power cable (9968-
242).
5 Power (+) n/a
3 Power (+) Red 10.5 to 33 VDC; Up to 9 Amps. Draws up to 2.3
watts when powered off. These pins, when paired to
ground (2 and 6), will power the device but will not
charge the batteries. Not powered through the
universal power adapter (9968-232).
4 Power (+) Red
2 Power (-) Black Ground
6 Power (-) Black
Table 2-1. Pin assignments for the connector and power cable.
Figure 2-2. Pins for the power cable (left) and instrument power connector (right).
Connecting with the instrument
Connect with the instrument using a web browser on a computer, tablet, or smart
phone that is on the same network as the instrument. Windows, macOS, Linux,
iOS, and Android OS are supported operating systems. Chrome, Firefox, and Safari
are supported browsers, but others may work as well.
2-4 LI-7820 N₂O/H₂O Gas Analyzer