AP200 CO2/H2O Atmospheric Profile System
Complete, Integrated System
Preprogrammed and low power
weather applications water applications energy applications gas flux and turbulence applications infrastructure applications soil applications

Overview

The AP200 is a complete, integrated CO2 and H2O atmospheric profile system. It measures carbon dioxide (CO2) and water vapor (H2O) concentration from up to eight intakes, which are normally spaced along the height of a tower to give a vertical profile. The AP200 is often used in conjunction with an eddy-covariance system to measure the storage term and give a more complete measure of the surface gas exchange.


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Benefits and Features

  • Fully integrated system
  • Requires only 13 W (average at 25°C and 12 Vdc)
  • Contains a Campbell Scientific CR1000X Measurement and Control Datalogger
  • Automatically performs CO2 zero and span
  • Automated temperature and pressure control
  • Data logger program included

Images

<dl><dt>Typical AP200 Installation</dt> <dd>1-27693 Heated Sample Intake Assemblies (from 4 up to 8)</dd> <dd>2-9922 20 AWG Power Cable</dd> <dd>3-28547 AP200 System Enclosure</dd> <dd>4-15702 Tubing</dd> <dd>5-Zero/Span Tanks and Regulators (not included)</dd> <dd>6-Instrument Tower (sold separately)</dd></dl>

Detailed Description

Measurements

Primary:

  • CO2 concentration at each intake
  • H2O concentration at each intake
  • System diagnostic word

Secondary:

  • Sample flow rate
  • Sample cell pressure
  • Sample cell temperature
  • Other control variables

Note: Contact the Micromet Group at Campbell Scientific for questions or updates regarding the datalogger program.

Specifications

System Enclosure
Operating Temperature -30° to +45°C
Power Requirements
  • 10 to 16 Vdc (voltage)
  • 13 W (average power at 25°C)
    Average power varies from 12.5 W above +35°C to 22.5 W at -30°C.
  • 3.75 A (45 W) maximum power (cold startup)
Dimensions 52.1 x 44.5 x 29.7 cm (20.5 x 17.5 x 11.7 in.)
Weight
  • 15.9 kg (35 lb) for AP200 base model
  • 1 kg (2.3 lb) for LI-850
  • 272 g (10 oz) for CR1000KD
  • 154 g (5.4 oz) for CFM100/NL116

Pump Module
Pump Type Dual-head diaphragm pump with a brushless dc motor
Mounting Mounted in an insulated, temperature-controlled box inside system enclosure
Control Pumping speed is automatically controlled to maintain the pump inlet pressure at the set point
Maximum Pumping Speed 9.0 liters per minute (LPM)
Pressure Sensor Range 15.0 to 115.0 kPa
Heater 8.0 W (turns on/off at 2°C)
Warm-up Time ~50 min (from -30° to +2°C)
Fan 0.7 W (turns on at 50°C and off at 45°C)

Valve Manifold
Mounting Mounted inside system enclosure
Inlets Eight air sample inlets plus one inlet for zero, one inlet for CO2 span, and one inlet for H2O span
Connections 0.25-in Swagelok
Mass Flow Sensor 0 to 1.0 standard liters per minute (SLPM)
Heater 8.0 W (turns on/off at 5°C)
Warm-up Time ~20 min (from -30° to +4°C)
Fan 0.7 W (turns on at 45°C and off at 43°C)

Intake Assembly
Filter 1.0-in diameter, sintered stainless-steel disk filter, 10-micron pore size
Orifice Heater 2 kohm (0.07 W at 12 Vdc)
Mixing Volume 750 mL
Sample Connection 0.25 in. Swagelok
Number of Connections for Heater Cable Entry Seals 3 (1 in, 2 out)
Cable Diameter for Heater Cable Entry Seals 2.8 to 6.6 mm (0.11 to 0.26 in.)
Wire Diameter for Heater Cable Screw Terminals 26 to 12 AWG
Wire Stripping Length for Heater Cable Screw Terminals 5.0 mm (0.2 in.)
Screw Tightening Torque for Heater Cable Screw Terminals 0.4 N•m
Orifice Inside Diameter 0.178 mm (0.007 in.)
Dimensions 31 x 12.5 x 19 cm (12 x 5 x 7.5 in.)
Weight 1.4 kg (3.1 lb)

Downloads

AP200 CR1000 Program v.2.01 (31.3 KB) 12-01-2021

AP200 CR1000(X) Program.

Compatible with the LI-850.

Note: For those with the LI-840 contact Campbell Scientific for compatible code.

View Revision History

Device Configuration Utility v.2.30 (46.9 MB) 02-10-2024

A software utility used to download operating systems and set up Campbell Scientific hardware. Also will update PakBus Graph and the Network Planner if they have been installed previously by another Campbell Scientific software package.

Supported Operating Systems:

Windows 11 or 10 (Both 32 and 64 bit)

View Revision History

Frequently Asked Questions

Number of FAQs related to AP200: 52

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  1. Do the intake tubes on the AP200 have to be the same length?

    No.

  2. Can bulk cable be purchased and cut to length in the field?
    Yes. Cutting cable to length and preparing the ends in the field is easy because the connections are either spring-loaded or screw terminals.
  3. Are the intake heaters of the AP200 wired in series or in parallel?

    The intake heaters are wired in parallel, so that each heater sees a nominal 12 Vdc.

  4. Why does the AP200 system use so much power at lower temperatures?

    The LI-840A uses a heater to maintain its sample cell at +50°C. Therefore, it consumes a lot more power at lower temperatures. Below 0°C, the valve heater also requires some power to keep the valves warm.

  5. How many intake assemblies are needed on an AP200?

    The number of intakes required at a site depends on the characteristics of the canopy. For example, the canopy’s height and density directly affect the change in CO2 and H2O concentrations. Order enough intakes to accurately profile these concentration changes. The AP200 may be ordered with anywhere from four to eight intake assemblies.

  6. How should the intake assemblies be spaced on a tower?

    The spacing depends on the canopy and atmospheric conditions. It is important to know where the concentration gradients are the steepest.

    For example, in a low agricultural crop canopy, it may be appropriate to use a logarithmic distribution within and near the top of the canopy, and a linear distribution above the canopy: 0.2 m, 0.4 m, 0.8 m, 1.6 m, 3.2 m (logarithmic) and 5 m, 7 m, 9 m (linear).

  7. How often should the intake filters be changed on an AP200?
    This depends on the site. Replace the filters when the sample intake flow is 75% of the flow with clean filters. As an example, long-term testing in Logan, UT, shows that filters need to be changed about once per year. If the air at a site is dirtier, then the filters will need to be replaced more often.
  8. Why should AP200 intakes be numbered from bottom to top?

    Numbering this way helps reduce the time skew between measurements of the intakes. To illustrate this, consider a parcel of air that moves through the intake tubes at approximately 0.5 m/s. If the longest tube is 60 m longer than the shortest tube, its travel time is two minutes longer than the shortest tube. Sampling from the shortest tube first means that the air samples enter each tube at the same time.

  9. The IRGA operates at reduced pressure in the AP200. Is it OK to do a zero/span at ambient pressure?

    Yes. The LI-840A has active pressure compensation that corrects its measurements for sample cell pressures from 15 to 115 kPa.

  10. Can the AP200 be used with chambers?
    It depends on the type of chambers. The AP200 requires a constant flow of sample air for each intake, so it will not work with small chambers that require the air sample to recirculate. However, it might be possible to use the AP200 with chambers that allow a continuous sample flow to be extracted.
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