Campbell Scientific AP200 User Manual

INSTRUCTION MANUAL

AP200 CO2/H2O

Copyright © 2012- 2014

Campbell Scientific, Inc.

Atmospheric Profile System

Revision: 4/14

Limited Warranty

“Products manufactured by CSI are warranted by CSI to be free from defects in
materials and workmanship under normal use and service for twelve months
from the date of shipment unless otherwise specified in the corresponding
product manual. (Product manuals are available for review online at

www.campbellsci.com.) Products not manufactured by CSI, but that are resold

by CSI, are warranted only to the limits extended by the original manufacturer.
Batteries, fine-wire thermocouples, desiccant, and other consumables have no
warranty. CSI’s obligation under this warranty is limited to repairing or
replacing (at CSI’s option) defective Products, which shall be the sole and
exclusive remedy under this warranty. The Customer assumes all costs of
removing, reinstalling, and shipping defective Products to CSI. CSI will return
such Products by surface carrier prepaid within the continental United States of
America. To all other locations, CSI will return such Products best way CIP
(port of entry) per Incoterms ® 2010. This warranty shall not apply to any
Products which have been subjected to modification, misuse, neglect, improper
service, accidents of nature, or shipping damage. This warranty is in lieu of all
other warranties, expressed or implied. The warranty for installation services
performed by CSI such as programming to customer specifications, electrical
connections to Products manufactured by CSI, and Product specific training, is
part of CSI's product warranty. CSI EXPRESSLY DISCLAIMS AND

EXCLUDES ANY IMPLIED WARRANTIES OF MERCHANTABILITY
OR FITNESS FOR A PARTICULAR PURPOSE. CSI hereby disclaims,
to the fullest extent allowed by applicable law, any and all warranties and
conditions with respect to the Products, whether express, implied or
statutory, other than those expressly provided herein.”

Assistance

Products may not be returned without prior authorization. The following
contact information is for US and international customers residing in countries
served by Campbell Scientific, Inc. directly. Affiliate companies handle
repairs for customers within their territories. Please visit

www.campbellsci.com to determine which Campbell Scientific company serves

your country.

To obtain a Returned Materials Authorization (RMA), contact CAMPBELL
SCIENTIFIC, INC., phone [phone]. After an application engineer
determines the nature of the problem, an RMA number will be issued. Please
write this number clearly on the outside of the shipping container. Campbell
Scientific’s shipping address is:

CAMPBELL SCIENTIFIC, INC.
RMA#_____
815 West 1800 North
Logan, Utah 84321-1784

For all returns, the customer must fill out a “Statement of Product Cleanliness
and Decontamination” form and comply with the requirements specified in it.
The form is available from our web site at www.campbellsci.com/repair. A
completed form must be either emailed to [e-mail] or faxed to
[phone]. Campbell Scientific is unable to process any returns until we
receive this form. If the form is not received within three days of product
receipt or is incomplete, the product will be returned to the customer at the
customer’s expense. Campbell Scientific reserves the right to refuse service on
products that were exposed to contaminants that may cause health or safety
concerns for our employees.

Precautions

DANGER — MANY HAZARDS ARE ASSOCIATED WITH INSTALLING, USING, MAINTAINING, AND WORKING ON OR AROUND

TRIPODS, TOWERS, AND ANY ATTACHMENTS TO TRIPODS AND TOWERS SUCH AS SENSORS, CROSSARMS, ENCLOSURES,
ANTENNAS, ETC. FAILURE TO PROPERLY AND COMPLETELY ASSEMBLE, INSTALL, OPERATE, USE, AND MAINTAIN TRIPODS,

TOWERS, AND ATTACHMENTS, AND FAILURE TO HEED WARNINGS, INCREASES THE RISK OF DEATH, ACCIDENT, SERIOUS
INJURY, PROPERTY DAMAGE, AND PRODUCT FAILURE. TAKE ALL REASONABLE PRECAUTIONS TO AVOID THESE HAZARDS.
CHECK WITH YOUR ORGANIZATION'S SAFETY COORDINATOR (OR POLICY) FOR PROCEDURES AND REQUIRED PROTECTIVE
EQUIPMENT PRIOR TO PERFORMING ANY WORK.

Use tripods, towers, and attachments to tripods and towers only for purposes for which they are designed. Do not exceed design
limits. Be familiar and comply with all instructions provided in product manuals. Manuals are available at www.campbellsci.com or
by telephoning 435-227-9000 (USA). You are responsible for conformance with governing codes and regulations, including safety
regulations, and the integrity and location of structures or land to which towers, tripods, and any attachments are attached. Installation
sites should be evaluated and approved by a qualified engineer. If questions or concerns arise regarding installation, use, or
maintenance of tripods, towers, attachments, or electrical connections, consult with a licensed and qualified engineer or electrician.

General

• Prior to performing site or installation work, obtain required approvals and permits. Comply

with all governing structure-height regulations, such as those of the FAA in the USA.

• Use only qualified personnel for installation, use, and maintenance of tripods and towers, and

any attachments to tripods and towers. The use of licensed and qualified contractors is highly
recommended.

• Read all applicable instructions carefully and understand procedures thoroughly before

beginning work.

• Wear a hardhat and eye protection, and take other appropriate safety precautions while

working on or around tripods and towers.

• Do not climb tripods or towers at any time, and prohibit climbing by other persons. Take

reasonable precautions to secure tripod and tower sites from trespassers.

• Use only manufacturer recommended parts, materials, and tools.

Utility and Electrical

• You can be killed or sustain serious bodily injury if the tripod, tower, or attachments you are

installing, constructing, using, or maintaining, or a tool, stake, or anchor, come in contact with
overhead or underground utility lines.

• Maintain a distance of at least one-and-one-half times structure height, or 20 feet, or the

distance required by applicable law, whichever is greater, between overhead utility lines and
the structure (tripod, tower, attachments, or tools).

• Prior to performing site or installation work, inform all utility companies and have all

underground utilities marked.

• Comply with all electrical codes. Electrical equipment and related grounding devices should

be installed by a licensed and qualified electrician.

Elevated Work and Weather

• Exercise extreme caution when performing elevated work.

• Use appropriate equipment and safety practices.

• During installation and maintenance, keep tower and tripod sites clear of un-trained or non-

essential personnel. Take precautions to prevent elevated tools and objects from dropping.

• Do not perform any work in inclement weather, including wind, rain, snow, lightning, etc.

Maintenance

• Periodically (at least yearly) check for wear and damage, including corrosion, stress cracks,

frayed cables, loose cable clamps, cable tightness, etc. and take necessary corrective actions.

• Periodically (at least yearly) check electrical ground connections.

WHILE EVERY ATTEMPT IS MADE TO EMBODY THE HIGHEST DEGREE OF SAFETY IN ALL CAMPBELL SCIENTIFIC PRODUCTS,
THE CUSTOMER ASSUMES ALL RISK FROM ANY INJURY RESULTING FROM IMPROPER INSTALLATION, USE, OR
MAINTENANCE OF TRIPODS, TOWERS, OR ATTACHMENTS TO TRIPODS AND TOWERS SUCH AS SENSORS, CROSSARMS,
ENCLOSURES, ANTENNAS, ETC.

Table of Contents

PDF viewers: These page numbers refer to the printed version of this document. Use the
PDF reader bookmarks tab for links to specific sections.

1. Introduction ................................................................. 1

2. Cautionary Statements ............................................... 1

3. Initial Inspection ......................................................... 2

4. Overview ...................................................................... 2

4.1 System Components ............................................................................. 2

4.1.1 Standard Components ................................................................... 2

4.1.2 Optional Components ................................................................... 4

4.1.3 Common Accessories .................................................................... 6

4.1.4 Other Accessories ......................................................................... 9

4.1.5 Support Software .......................................................................... 9

4.1.6 Replacement Parts ....................................................................... 10

4.2 Theory of Operation ........................................................................... 11

4.2.1 Intake Assemblies ....................................................................... 13

4.2.2 Valve Manifold ........................................................................... 15

4.2.3 Pump Module .............................................................................. 16

4.3 Specifications ..................................................................................... 18

4.3.1 CO2/H2O Analyzer ...................................................................... 18

4.3.2 System Enclosure ........................................................................ 18

4.3.3 Intake Assembly .......................................................................... 20

5. Installation ................................................................. 20

5.1 Mounting ............................................................................................ 20

5.1.1 Support Structure ........................................................................ 20

5.1.2 AP200 Enclosure ........................................................................ 21

5.1.3 Intake Assemblies ....................................................................... 21

5.2 Plumbing ............................................................................................ 23

5.2.1 Profile Sample Tubes .................................................................. 23

5.2.2 Zero and CO2 Span ..................................................................... 25

5.2.3 H2O Span .................................................................................... 26

5.3 Wiring ................................................................................................ 27

5.3.1 Ground Connection ..................................................................... 27

5.3.2 Intake Heater Cables ................................................................... 28

5.3.3 Power .......................................................................................... 32

5.4 Configure the Program ....................................................................... 34

5.4.1 System Configuration Variables ................................................. 35

5.4.2 Compile Switches ....................................................................... 37

5.5 Starting and Stopping the Sequence ................................................... 37

5.6 Verify Performance ............................................................................ 38

5.6.1 Quick Status Check Using a Keyboard Display .......................... 38

5.6.2 Checking Status Remotely .......................................................... 39

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Table of Contents

5.6.3 On-site System Checks ............................................................... 39

6. Infrared Gas Analyzer (IRGA) Zero and Span ......... 40

6.1 Automatic Zero and Span .................................................................. 40

6.2 Manual Zero and Span ....................................................................... 41

6.2.1 Check Zero and CO2 Span .......................................................... 41

6.2.2 Do CO2 and H2O Zero ................................................................ 42

6.2.3 Do CO2 Span .............................................................................. 43

6.2.4 Do H2O Span .............................................................................. 44

6.2.5 Restart the Sequence .................................................................. 46

6.2.6 Check the System ....................................................................... 46

7. Maintenance and Troubleshooting .......................... 46

7.1 Plumbing Leaks ................................................................................. 46

7.2 Enclosure Desiccant .......................................................................... 47

7.3 Intake Filters ...................................................................................... 47

7.4 LI-840A (IRGA) ................................................................................ 50

7.4.1 Installing and Removing the IRGA ............................................ 50

7.4.2 Configuring the IRGA ................................................................ 51

7.5 Zero/Span Flow ................................................................................. 52

8. Repair ......................................................................... 53

Appendices

A.

Keyboard Display Menu ......................................... A-1

B. AP200 Diagnostics .................................................. B-1

C. Public Variables ...................................................... C-1

D. Output Tables .......................................................... D-1

E. Temperature Profile ................................................ E-1

F. Valve Sequence Timing .......................................... F-1

G. AC/DC Adapter Kit .................................................. G-1

H. Using Swagelok® Fittings ....................................... H-1

H.1 Assembly ......................................................................................... H-1

H.2 Common Replacement Parts ........................................................... H-2

I. Useful Equations ...................................................... I-1

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Table of Contents

J. AP200 Pump Replacement ...................................... J-1

J.1 Introduction ....................................................................................... J-1

J.2 Removal ............................................................................................ J-1

J.3 Installation ......................................................................................... J-4

Figures

4-1. Interior of AP200 system enclosure ..................................................... 3

4-2. Side view of AP200 intake assembly ................................................... 3

4-3. Side view of earlier generation AP200 intake assembly ...................... 4

4-4. The IRGA installed in the AP200 system enclosure ............................ 4

4-5. Campbell Scientific NL115 and CFM100 CompactFlash® storage

modules ............................................................................................ 5

4-6. CFMC2G 2GB CompactFlash® memory card ..................................... 5

4-7. AP200 keyboard display mounted in system enclosure ....................... 6

4-8. AC/DC power adapter kit installed in AP200 ...................................... 7

4-9. 17752 USB memory card reader/writer ............................................... 8

4-10. 107-L temperature probe mounted with radiation shield ..................... 8

4-11. CR1000KD handheld keyboard/display ............................................... 9

4-12. Syringe filter of current AP200 intake assembly ............................... 10

4-13. Disk filter of early AP200 intake assembly ........................................ 10

4-14. Single desiccant pack ......................................................................... 10

4-15. Humidity indicator card ..................................................................... 11

4-16. Diaphragm pump used in AP200 ....................................................... 11

4-17. Plumbing diagram of AP200 system .................................................. 12

4-18. AP200 intake assembly shown open .................................................. 13

4-19. Nominal ambient pressure as related to increasing elevation ............. 14

4-20. Nominal sample flow rate as related to increasing ambient

pressure ........................................................................................... 14

4-21. Valve module and Swagelok® feedthrough fittings on bottom

of AP200 enclosure ........................................................................ 15

4-22. Pump module of AP200 system ......................................................... 17

4-23. Average power consumption relative to temperature ......................... 19

5-1. Installation (showing mounting hardware) of AP200 system

enclosure on UT30 tower ............................................................... 21

5-2. Mounting clip orientation for pipe diameters between 1.3 and

3.8 cm ............................................................................................. 22

5-3. Mounting clip orientation for pipe diameters between 3.9 and

5.1 cm ............................................................................................. 23

5-4. Installation of AP200 assembly on a small-diameter pipe (left)

and large-diameter pipe (right) ....................................................... 23

5-5. Tubing connections on bottom of AP200 enclosure .......................... 24

5-6. Labeled inlet connections inside enclosure ........................................ 24

5-7. Tubing connections from four intake assemblies connected to

inlets 1 – 4 ...................................................................................... 25

5-8. AP200 system enclosure configured with cylinders of zero air

and CO

5-9. H2O span inlet configured for a dewpoint generator .......................... 27

5-10. AP200 earth grounded on a UT30 tower ............................................ 27

5-11. Cable feedthrough cap shown removed to admit cables into the

system enclosure ............................................................................. 28

5-12. Proper wiring of heater cable onto DIN bus of AP200 system

enclosure ......................................................................................... 29

5-13. Use AP200 system screwdriver to open contacts for wiring heater

cable ................................................................................................ 29

.......................................................................................... 26

2

iii

Table of Contents

5-14. Tabs for opening intake assembly ..................................................... 30

5-15. Wiring of heater cable on AP200 intake assembly ............................ 30

5-16. Three intake assemblies with heater cables daisy chained to the

AP200 system enclosure ................................................................ 31

5-17. Proper wiring of power cable onto DIN bus of AP200 system

enclosure ........................................................................................ 33

5-18. Power cables secured to cable tie loop on pump module of AP200

enclosure ........................................................................................ 33

5-19. Cut-away view showing proper replacement of feedthrough cap ...... 34

7-1. Releasing rain diverter from intake assembly ................................... 48

7-2. Order of replacement for orifice, filter, and rain diverter .................. 49

7-3. Correct reassembly after filter replacement ....................................... 49

7-4. Installed IRGA in system enclosure .................................................. 50

7-5. Components and fittings of IRGA installation .................................. 51

E-1. 107-L temperature probe mounted with radiation shield .................. E-1

G-1. Installation location of power adapter ............................................. G-1

G-2. Bundled cable of power adapter ...................................................... G-1

G-3. Cable extension connected to AP200 power input terminal ............ G-2

G-4. AC power cord secured within AP200 system enclosure ................ G-3

G-5. Power adapter output cable plugged into cable extension ............... G-3

H-1. Swagelok® insert ............................................................................. H-3

H-2. Front and back Swagelok® ferrules ................................................. H-3

H-3. Swagelok® plug ............................................................................... H-4

H-4. Swagelok® cap ................................................................................. H-4

J-1. Location of pump enclosure inside AP200 system enclosure ...........J-1

J-2. Location of six screws of pump enclosure cover ...............................J-2

J-3. AP200 pump ......................................................................................J-2

J-4. Location of pump connector in AP200 pump electronics .................J-3

J-5. Self-tapping screws attaching pump to metal box .............................J-3

J-6. Location of cuts to remove pump assembly from tubing ..................J-4

J-7. Inlet and outlet tubing reconnected to pump .....................................J-4

J-8. Pump side with inlet and outlet tubing connected .............................J-5

Tables

5-1. Equivalent Resistance for Intake Heaters Connected in Parallel ....... 32

7-1. IRGA Settings ................................................................................... 52

7-2. IRGA Outputs .................................................................................... 52

B-1. Summary of Bit Numbers Indicating Conditions Outside Normal

Operating Range .......................................................................... B-1

C-1. Public Variables .............................................................................. C-1

D-1. Variables of the IntAvg Table ......................................................... D-1

D-2. Variables of the CalAvg Table ........................................................ D-4

D-3. Variables of the SiteAvg Table ....................................................... D-6

D-4. Variables of the RawDataTable ....................................................... D-8

D-5. Variables of the TimeInfo Table ................................................... D-10

D-6. Variables of the message_log Table .............................................. D-12

F-1. Profile Sequence-timing Variables ................................................... F-1

F-2. System Configuration Variables of Zero/Span ................................. F-3

F-3. Timing for Zero/Span Sequence (check only) .................................. F-4

F-4. Timing for Zero/Span Sequence (setting the IRGA) ........................ F-5

H-1. Available Plastic Tubing Sizes, Construction, and Usage

Guidelines .................................................................................... H-2

H-2. Dimensions and Part Numbers for Swagelok® Inserts .................... H-3

H-3. Dimensions and Part Numbers for Swagelok® Ferrules .................. H-3

iv

Table of Contents

H-4. Dimensions and Part Numbers for Swagelok® Plugs ...................... H-4

H-5. Dimensions and Part Numbers for Swagelok® Caps ....................... H-5

v

Table of Contents

vi

AP200 CO2/H2O Atmospheric Profile
System

1. Introduction

The AP200 CO2/H2O Atmospheric Profile System (AP200) measures
atmospheric carbon dioxide and water vapor at up to eight positions. Intake
assemblies are normally spaced along the height of a tower to enable
measurement of a vertical profile. The AP200 is commonly used in
conjunction with an eddy-covariance system to measure the storage term to
give a more complete measurement of the surface exchange.

Before using the AP200, please study:

• Section 2, Cautionary Statements

• Section 3, Initial Inspection

• Section 5, Installation

Operational instructions critical to preserving accurate measurements of the
system are found throughout this manual. Before using the AP200, please
study the entire manual. Several other user manuals provide additional
information and should be consulted before using the AP200. These include:

• CR1000 Measurement and Control System Operator’s Manual

• CFM100 CompactFlash

• NL115 Ethernet and CompactFlash

• Application Note 3SM-F, CF Card Information

• ENC10/12, ENC12/14, ENC14/16, ENC16/18 Instruction Manual

• CM106 Tripod Instruction Manual

• Tripod Installation Manual Models CM110, CM115, CM120

• Model 107 Temperature Probe Instruction Manual

®

Module Instruction Manual

®

Module Instruction Manual

all available at www.campbellsci.com, and

• LI-840A CO

available at www.licor.com

2/H2

2. Cautionary Statements

• WARNING:

o The AP200 can be damaged by unfiltered air being pulled into the

sampling sub system. To avoid this, each inlet must be capped or
have a particulate filter installed before applying power to the
system. Use care when connecting and disconnecting intake
assembly tubes, and zero and span tubes (see Section 5.2,
Plumbing) to avoid introducing dust or other contaminates.

o Do not overtighten the Swagelok

or intake assemblies. See Appendix H, Using Swagelok
for information on proper connection.

O Gas Analyzer Instruction Manual

®

fittings on the sampling system

®

Fittings,

1

AP200 CO2/H2O Atmospheric Profile System

o Careful design of the power source for the AP200 should be

o Retain all spare caps and plugs as these are required when

3. Initial Inspection

Upon receipt of the AP200, inspect the packaging and contents for damage.
File damage claims with the shipping company.

Model numbers are found on each product. On cables, the model number is
often found at the connection end of the cable. Check this information against
the enclosed shipping documents to verify the expected products and the
correct lengths of cable are included.

4. Overview

The AP200 measures atmospheric carbon dioxide and water vapor at up to
eight positions. Intake assemblies are generally spaced along the height of a
tower to enable measurement of the vertical profile. The AP200 is commonly
used in conjunction with an eddy-covariance system to measure the storage
term to give a more complete measurement of the surface exchange.

undertaken to ensure uninterrupted power. If needed, contact a
Campbell Scientific applications engineer for assistance.

shipping or storing the AP200 system.

4.1 System Components

The AP200 consists of several components, some of which are optional. Some
additional accessories are required to complete a fully functioning AP200
system and are described and illustrated in the sections that follow.

4.1.1 Standard Components

Standard with the AP200 are the AP200 system enclosure and four to eight
intake assemblies.

The AP200 system enclosure always includes a sample pump, valve manifold,
CR1000 datalogger, and other electronics to control and monitor the system.
The components within the AP200 are shown in FIGURE 4-1. The CR1000
records data, selects valves, adjusts pumping speed to control system pressure,
and controls the temperatures of the pump and valve manifold.

2

AP200 CO2/H2O Atmospheric Profile System

FIGURE 4-1. Interior of AP200 system enclosure

The AP200 intake assembly (pn 27693) includes an orifice to set the flow rate,
a filter that removes particulates, and a rain diverter to admit a sample of
ambient air without allowing precipitation to enter. The rain diverter is heated
to prevent condensation. The intake assembly includes a mixing volume to
dampen fluctuations in ambient concentrations of CO

and H2O. The closed

2

intake assembly is shown in FIGURE 4-2.

FIGURE 4-2. Side view of AP200 intake assembly

3

AP200 CO2/H2O Atmospheric Profile System

NOTE

Rain Diverter

Intake assemblies shipped prior to August 2013 had the rain
diverter located at the end of the assembly rather than below, as
shown in

FIGURE 4-3. This assembly also uses a different filter,
which is shown in FIGURE 4-13
as pn 27809.

FIGURE 4-3. Side view of earlier generation AP200 intake assembly

, and available for replacement

4.1.2 Optional Components

The AP200 requires an LI-840A analyzer (manufactured by LI-COR®, Inc,
Lincoln, NE) to measure CO
analyzer (herein referred to as the IRGA) can be provided as a factory-installed
option or it can be provided by the user. The AP200 is designed for easy
installation of the LI-COR
enclosure is shown in FIGURE 4-4. For complete details, see the LI-840A
instruction manual, available at www.licor.com.

and H2O concentrations. This infrared gas

2

®

IRGA. The IRGA installed in the AP200

4

FIGURE 4-4. The IRGA installed in the AP200 system enclosure

AP200 CO2/H2O Atmospheric Profile System

To store data on a CompactFlash® (CF) memory card, the AP200 requires
either an NL115 or a CFM100 (FIGURE 4-5) both available from Campbell
Scientific. Either storage module will provide data storage. The NL115 has the
added capabilities provided by an Ethernet interface.

FIGURE 4-5. Campbell Scientific NL115 and CFM100 CompactFlash

®

storage modules

The AP200 can be ordered with either the NL115 or the CFM100 module
factory installed or it can be ordered with neither. If the AP200 is ordered
without a storage module, the user must provide one. The CF card (FIGURE
4-6) for the storage module can be ordered separately from

www.campbellsci.com (see Section 4.1.3, Common Accessories). For details,

see the CFM100 CompactFlash Module Instruction Manual or the NL115
Ethernet and CompactFlash Module Instruction Manual, and the Application
Note 3SM-F, CF Card Information. All manuals are available at

www.campbellsci.com.

®

FIGURE 4-6. CFMC2G 2GB CompactFlash

memory card

The AP200 can be ordered with an optional keyboard display factory mounted
in the system enclosure (FIGURE 4-7). This keyboard display provides a
convenient user interface to change settings or view status and data in the field.

5

AP200 CO2/H2O Atmospheric Profile System

NOTE

FIGURE 4-7. AP200 keyboard display mounted in system enclosure

This user interface is also available using a hand-held,
detachable keyboard display, the CR1000KD, as described in
Section

4.1.4, Other Accessories. The CR1000KD may be
preferred when multiple AP200s are to be maintained. The
factory-mounted keyboard display is permanently attached, so it
cannot be forgotten or misplaced. For more detail on the
keyboard display, see the CR1000 Measurement and Control
System Operator’s Manual.

The AP200 can be configured with one of several mounting options for the
system enclosure. The AP200 system enclosure is similar to the Campbell
Scientific ENC16/18 enclosure. The same mounting options are available and
outlined below:

• Triangular tower (UT10, UT20, or UT30)

• Tripod mast (1.5 in to 1.9 in diameter)

• Tripod leg (CM106 or CM106K tripod only)

• Large pole (4.0 in to 10.0 in diameter)

• No mounting bracket

Consult the ENC10/12, ENC12/14, ENC14/16, ENC16/18 Instruction Manual,
available at www.campbellsci.com, for details on mounting bracket options.

4.1.3 Common Accessories

Additional accessories are required to conduct sampling with the AP200.
Some of the most common accessories are described here.

Tubing for Sampling: A sample tube must be used to bring the air sample
from each intake assembly to the AP200 system enclosure. Normally bulk
tubing is cut to length and installed on site. Campbell Scientific pn 15702 or
its equivalent is recommended. This tubing has a 0.25-in outer diameter to fit
the Swagelok

®

fittings on the intake assemblies and the system enclosure. The

6

AP200 CO2/H2O Atmospheric Profile System

tubing has an aluminum core to minimize diffusion through the tubing wall and
a UV-resistant, black, high-density polyethylene jacket. Maximum tubing
length available is a 500-ft roll.

Intake Heater Cabling: The intake assemblies have a small heater in the rain
diverter to prevent condensation. For normal applications, bulk cable is cut to
length and installed on site to provide power to the intake assemblies. Heater
cables may be daisy-chained from one intake assembly to the next. Campbell
Scientific pn 9922 cable or its equivalent is recommended for this connection.
This cable consists of a twisted red/black pair of wire gauge (AWG) 20 within
a rugged Santoprene jacket.

System Power Cable: The AP200 requires a cable to connect it to the user’s
battery or other power source. The same cable may be used for the system
power as for the heaters (pn 9922) if the length is short (less than 3 m, or 10 ft).
The AP200 requires a current from 1.0 A to 3.0 A, which will cause a voltage
drop in the power cable of 0.2 V to 0.6 V for a 10-ft length of pn 9922 cable.
The corresponding power loss is 0.2 W to 1.8 W. For most applications the
preferred power cable is CABLEPCBL-L. This cable consists of a twisted
red/black pair of wire gauge (AWG) 16 within a rugged Santoprene jacket. It
is cut to the specified length and the end finished for easy installation. The
voltage and power losses will be a factor of 2.5 smaller than for the pn 9922
cable. If the power cable must be longer than 8 m (25 ft), contact Campbell
Scientific.

AC/DC Power Adapter Kit: A power adapter kit can be configured within
the AP200 system enclosure to allow the AP200 to be powered from AC mains
power. The AC/DC Power Adapter Kit (pn 28549) is shown in FIGURE 4-8
and instructions for installing the adapter kit are given in Appendix G, AC/DC
Power Adapter Kit.

FIGURE 4-8. AC/DC power adapter kit installed in AP200

®

CF Card: The AP200 stores data on a CompactFlash

memory card. There
are two types of CF cards available today: Industrial Grade and Standard or
Commercial Grade. Industrial Grade PC/CF cards are certified to a higher
standard in that they are designed to operate over a wider temperature range,
offer better vibration and shock resistance, and have faster read/write times

7

AP200 CO2/H2O Atmospheric Profile System

than their commercial counterparts. Campbell Scientific recommends the use
of industrial-grade cards, such as the CFMC2G (FIGURE 4-6) available from
Campbell Scientific. For more details about this card, see Application Note
3SM-F, CF Card Information, available from www.campbellsci.com.

USB Memory Card Reader/Writer: The 17752 USB memory card
reader/writer, shown in FIGURE 4-9, is a single-slot, high-speed reader/writer
that allows a computer to read a memory card. When used with Campbell
Scientific equipment, the 17752 typically reads data stored on CompactFlash
cards, but it can read many different types of memory cards. The 17752
connects to the computer's USB port.

®

FIGURE 4-9. 17752 USB memory card reader/writer

Temperature Probes: The AP200 system can measure a temperature profile
at up to eight levels, using 107-L temperature probes. The 107 is a rugged,
accurate probe that measures air temperature from –35°C to +50°C. The "-L"
denotes that the cable length is specified at the time of order.

Radiation Shield: Each 107-L temperature probe is normally mounted with a
41303-5A radiation shield. The 41303-5A is a naturally aspirated, six-plate
radiation shield. Its louvered construction allows air to pass freely through the
shield, serving to keep the probe at or near ambient temperature. The shield's
white color reflects solar radiation.

The temperature probe with its accompanying radiation shield is shown in
FIGURE 4-10.

8

FIGURE 4-10. 107-L temperature probe mounted with radiation shield

4.1.4 Other Accessories

Portable Keyboard: The CR1000KD, shown in FIGURE 4-11, is a portable
keyboard and display screen for the CR1000 datalogger. The CR1000KD can
check the datalogger's status, display or plot sensor readings and stored values,
and allows the user to enter numeric data. It is similar to the hard-mounted
keyboard/display option for the AP200, but the CR1000KD may be carried
from station to station and is useful when multiple AP200s are being
maintained.

AP200 CO2/H2O Atmospheric Profile System

FIGURE 4-11. CR1000KD handheld keyboard/display

4.1.5 Support Software

There are several software products available from Campbell Scientific to
allow the user to connect a PC to the AP200’s datalogger.

PC200W: PC200W is a free, starter software package that provides basic
tools (clock set, program download, monitor data, retrieve data, etc.). The
PC200W supports direct connections between PC and datalogger but has no
telecommunications or scheduled data-collection support.

PC400: PC400 is a mid-level software package that supports a variety of
telecommunication options, manual data collection, data display, and includes
a full-featured CRBasic program editor. PC400 does not support combined
communication options (for example, phone-to-RF), PakBus® routing, or
scheduled data collection.

LoggerNet: LoggerNet is a full-featured software package that supports
programming, communication, and data collection and display. LoggerNet
consists of a server application and several client applications integrated into a
single product. This package is recommended for applications that require
telecommunications support or scheduled data retrieval, or for large datalogger
networks.

LoggerLink Mobile Apps: The LoggerLink Mobile Apps allows an iOS or
Android device to communicate with an IP-enabled datalogger such as the

9

AP200 CO2/H2O Atmospheric Profile System

CR1000 in the AP200. The apps support field maintenance tasks such as
viewing and collecting data, setting the clock, and downloading programs.

4.1.6 Replacement Parts

Syringe Filter: Intake assemblies shipped after August 2013 use a syringe
filter with Luer lock connections. The filter is an in-line 2.5-cm (1.0-in)
diameter, PTFE membrane filter (FIGURE 4-12) of 3-micron pore size. It is
used to replace dirty filter elements in the AP200 intake assembly and is
available as pn 29998.

FIGURE 4-12. Syringe filter of current AP200 intake assembly

Disk Filter: Intake assemblies shipped prior to August 2013 used a different
filter, pn 27809. This filter is a 2.5-cm (1.0-in) diameter, sintered stainless
steel disk filter (FIGURE 4-13) of 10-micron pore size. It is used to replace
dirty filter elements in the AP200 intake assembly.

FIGURE 4-13. Disk filter of early AP200 intake assembly

Silica Desiccant Bags: The 4905 Single 4-unit Silica Desiccant Bag (FIGURE
4-14) is used to desiccate the AP200 system enclosure and should be
periodically replaced. The 4905 can be purchased in quantities of 20 as pn

6714.

10

FIGURE 4-14. Single desiccant pack

AP200 CO2/H2O Atmospheric Profile System

Humidity Indicator Card: The replacement humidity indicator (FIGURE
4-15) card is pn 28878.

FIGURE 4-15. Humidity indicator card

Diaphragm Pump: The pump module for the AP200 includes a small double­head diaphragm pump with a brushless DC motor. The pump includes a speed­control input and a tachometer to measure actual pumping speed. It is mounted
in an insulated, temperature-controlled box inside the AP200 system enclosure.
If the pump fails, the replacement pump (FIGURE 4-16) is available as pn

26402. See Appendix J, AP200 Pump Replacement, for instructions on
replacing the pump. The part includes the connector for easy installation.

FIGURE 4-16. Diaphragm pump used in AP200

4.2 Theory of Operation

The AP200 system measures CO2 and H2O concentrations at multiple locations
by pulling a continuous sample flow from each of several (four to eight) intake
assemblies. Solenoid valves direct sample flow from one intake assembly at a
time, through a CO

O IRGA. A CR1000 datalogger records data, selects

2/H2

11

AP200 CO2/H2O Atmospheric Profile System

valves, adjusts pumping speed to control system pressure, and controls the
temperatures of the pump and valve manifold. FIGURE 4-17 is a plumbing
diagram showing the various parts of the AP200 system connected. Details for
each part of the system are given in this section.

12

FIGURE 4-17. Plumbing diagram of AP200 system

4.2.1 Intake Assemblies

The AP200 intake assembly (pn 27693) includes a heated rain diverter, an
inline filter, an orifice, and a mixing volume on a common mounting bracket
with rain cover, shown opened in FIGURE 4-18. The inline filter element, pn
29998, is a 2.5-cm (1.0-in) diameter, PTFE membrane with a 3-micron pore
size. It removes particulates from the air sample that could clog the orifice or
valve.

AP200 CO2/H2O Atmospheric Profile System

FIGURE 4-18. AP200 intake assembly shown open

The orifice has a diameter of 0.18 mm (0.007 in) to restrict flow to a

-1

maximum of approximately 247 standard ml•min

at sea level. The flow will
be reduced at higher elevations due to the lower atmospheric pressure. The
nominal ambient pressure as a function of elevation is shown in FIGURE 4-19.

13

AP200 CO2/H2O Atmospheric Profile System

65

70

75

80

85

90

95

100

105

0 500 1000 1500 2000 2500 3000

Elevation (m)

Ambient Pressure ( kPa)

180

190

200

210

220

230

240

250

70 75 80 85 90 95 100

Ambient Pressure (kPa)

Sample Flow (ml/min)

FIGURE 4-19. Nominal ambient pressure as related to increasing

elevation

FIGURE 4-20 shows the nominal sample flow as a function of ambient
pressure, assuming a 35-kPa pressure drop across the orifice.

14

FIGURE 4-20. Nominal sample flow rate as related to increasing

ambient pressure

Taken together, these two graphs show that the nominal flow varies from 247
ml/min at sea level to 180 ml/min at 3000 m. The flow rate is reported in
public variable sample_flow. Some variation in flow (approximately 10%) is
to be expected due to variation in the actual size of the orifices and in the
calibration of the flow sensor. For example, at an elevation of 1000 m, the
nominal ambient pressure is 90 kPa, which gives a nominal flow of 225
ml/min. The normal expected range for the flow would be from ~200 to ~250
ml/min.

AP200 CO2/H2O Atmospheric Profile System

The flow will also vary with ambient temperature due to the corresponding
change in air density. Higher-temperature air has lower density, which will
have lower flow (approximately 2% lower flow for a 10°C temperature
change).

The sample flow will decrease over time as particulates clog the filters.
Eventually, the flow will be reduced to the extent that it will degrade the
equilibration time after an intake is selected. As a general guideline, the filters
should be replaced when the flow decreases by 25%. The filters will normally
last a few months, but will require more frequent changes in dirty conditions.

The intake assembly has been designed with two separate elements intended to
prevent condensation. First, the rain diverter has a small heater (0.25 W at 12
Vdc) to warm the air sample to approximately 10°C above ambient
temperature before reaching the filter and orifice. This prevents condensation
on surfaces upstream of the orifice. Second, the flow path downstream of the
orifice is kept at reduced pressure (typically 35 kPa below ambient pressure) to
prevent condensation.

The intake assembly includes a mixing volume to dampen fluctuations in the

and H2O concentrations. Assuming the nominal dependence of pressure

CO

2

and flow on elevation, and a 35-kPa pressure drop at the orifice, the mixing
volume residence time will vary from 2.0 min at sea level to 1.5 min at 3000
m. This residence time is similar to the time to cycle through all of the intakes
(1 to 2 min, depending on the number of intakes used). This ensures that a
transient change in atmospheric CO

or H2O concentration will be measured by

2

each of the intakes, regardless of when it occurs during the valve-switching
cycle.

4.2.2 Valve Manifold

The valve manifold is mounted on the bottom of the AP200 system enclosure.
It has LEDs to show which valve is active and the state of the heater and fan.
It has stainless steel tubes that connect the manifold to Swagelok
fittings on the bottom of the enclosure as shown in FIGURE 4-21.

FIGURE 4-21. Valve module and Swagelok

bottom of AP200 enclosure

®

feedthrough

®

feedthrough fittings on

15

AP200 CO2/H2O Atmospheric Profile System

The valve manifold has eleven inlets (eight for air samples and three for
zero/span) and two outlets (sample and bypass). Each air sample inlet has a
three-way solenoid valve that connects it to one of the two outlets. This valve
connects its corresponding inlet to the bypass outlet when it is off and to the
sample outlet when it is energized. The sample outlet connects to the IRGA
and the bypass outlet connects directly to the pump. Therefore, the sample
inlets will have a continuous flow, regardless of which inlet is sampled by the
IRGA. This continuous flow stores an air-sample history in the intake
assembly mixing volumes, keeps the mixing volumes and sample tubes at low
pressure to prevent condensation, and minimizes flow and pressure transients
caused by valve switching.

The zero/span inlets are not bypassed, thereby allowing flow only when they
are selected. These inlets have flow restriction tubes connecting the bulkhead
fittings to the valve manifold to set the flow. These tubes have the same outer
diameter (0.062 in) as the ones for the air sample inlets, but they have a smaller
inner diameter (0.015 in, compared to 0.040 in). This provides a flow
restriction similar to the orifices in the AP200 intake assemblies. The flow for
the zero and CO

The valve manifold has a mass flow sensor on the sample outlet. This sensor’s
measurements are reported in public variable sample_flow.

span cylinders is affected by the pressure regulator setting.

2

The valve manifold temperature is reported in public variable valve_tmpr. The
operating range of the valves is 4°C to 49°C. If the valve temperature is outside
this range, the AP200 will disable the valves and pump.

The valve module has a heater (8 W) that turns on if the valve temperature falls
below 5°C. If the AP200 is started at cold temperature it may take up to 20
minutes to warm the valve module (from –30°C to +4°C). When it reaches 5°C
the heater will cycle on/off as needed to maintain this temperature. The fraction
of time the valve heater is on is reported in the output tables (IntAvg, CalAvg,
and SiteAvg) as valve_heat_Avg. This will typically increase from zero at 0°C
ambient temperature to 0.5 (4 W average power) at –30°C.

The valve module has a fan (0.7 W) that turns on if the valve temperature rises
above 45°C. The fan will stay on until the valve temperature falls below 43°C.
The fraction of time the valve fan is on is reported in the output tables (IntAvg,
CalAvg, and SiteAvg) as valve_fan_Avg. This will typically increase from
zero at 35°C ambient temperature to 1.0 (0.7 W average power) at 45°C.

4.2.3 Pump Module

The AP200 pump module is mounted on the left side of the AP200 system
enclosure as shown in FIGURE 4-22.

16

AP200 CO2/H2O Atmospheric Profile System

FIGURE 4-22. Pump module of AP200 system

The AP200 pump module pulls air through the system and exhausts it through
the Exhaust fitting on the bottom of the system enclosure. It uses a small
double-head diaphragm pump with a brushless DC motor. This pump includes
a speed control input and a tachometer to measure the actual pumping speed. It
is mounted in an insulated, temperature-controlled box inside the AP200
system enclosure. The following sections describe the monitored pump
operating parameters.

Pump Inlet Pressure: The measured inlet pressure of the pump is reported in
public variable pump_press. The AP200 sets the value of public variable
pump_control to a value between 0 (off) and 1 (full speed) to adjust the
pump’s speed as needed to match the measured pressure to the setpoint
pressure PUMP_P_SETPT. PUMP_P_SETPT is a system configuration
variable (see Section 5.4.1, System Configuration Variables). This pressure
setting affects the power required for the pump (lower pressure requires more
power), the possibility of water condensing in the tubing (lower pressure helps
to prevent condensation), and the flow rate (lower pressure will increase the
flow rate). The pump can achieve a maximum of approximately 60 kPa
pressure drop from ambient pressure at zero flow. The recommended setting
for the pump is 35 kPa below ambient pressure.

The pump module includes two buffer volumes to dampen the pressure
fluctuations from the pump. The sample flow from the IRGA flows through
these volumes in series on the way to the pump. The bypass flow (from non­selected inlets) connects directly to the pump.

Pump Speed: The measured pumping speed is reported in public variable
pump_speed. This is the rotational speed of the pump, given in Hz. The

pumping speed will typically be 25 Hz to 40 Hz. The actual value is not
critical, however, as long as the pressure can be maintained at the setpoint.

17

AP200 CO2/H2O Atmospheric Profile System

Pump Temperature: The temperature of the pump module is reported in
public variable pump_tmpr. The operating range of the pump is 0°C to 55°C.
If the pump temperature is outside this range, the AP200 will disable the pump.

The pump module has a heater (8 W) that turns on if the pump temperature
falls below 2°C. If the AP200 is started at cold temperature, it may take up to
50 minutes to warm the pump module (from –30°C to 0°C). When it reaches
2°C the heater will cycle on/off as needed to maintain this temperature. The
fraction of time the pump heater is on is reported in the output tables (IntAvg,
CalAvg, and SiteAvg) as pump_heat_Avg. Once the pump is warmed up and
starts running, it will normally keep itself warm without additional heat to
approximately –30°C ambient.

The pump module has a fan (0.7 W) that turns on if the pump temperature rises
above 50°C. The fan will stay on until the pump temperature falls below 45°C.
The fraction of time the pump fan is on is reported in the output tables
(IntAvg, CalAvg, and SiteAvg) as pump_fan_Avg. This will typically
increase from zero at 20°C ambient temperature to 0.5 (0.4 W average power)
at 45°C.

The outlet of the pump connects to a small volume to reduce noise, and then to
the Exhaust fitting on the bottom of the system enclosure. This fitting has a
screen to prevent insects or debris from entering when the pump is off. If
exhausting the air samples at this location is a problem (for example, if it is
close enough to an inlet to affect its measurement), this screen may be removed
and a tube may be attached to divert the pump exhaust to another location. The
screen may be attached to the end of the tube with a Swagelok
cases the screen may simply be left in place.

®

union. In most

4.3 Specifications

4.3.1 CO2/H2O Analyzer

CO2 and H2O are measured with an LI-840A IRGA. See the LI-840A manual
(available at www.licor.com) for specifications.

4.3.2 System Enclosure

Dimensions: 52.1 cm x 44.5 cm x 29.7 cm

Weight

AP200 base model: 15.9 kg (35.0 lb)

Options

IRGA: 1.0 kg (2.3 lb)
CR1000KD: 0.3 kg (0.7 lb)
CFM100/NL115: 0.2 kg (0.4 lb)

Operating Temperature: –30°C to 45°C

Power Requirement

Voltage: 10 Vdc to 16 Vdc
Power
Maximum (cold start up): 3.75 A at 12 V dc (45.0 W)

(20.5 in x 17.5 in x 11.7 in)

18