CPEC306 Expandable Closed-Path Eddy-Covariance System with EC155 and Pump Module
For Various Trace Gas Applications
Provides additional ports without automatic zero and span
weather applications water applications energy applications gas flux & turbulence applications infrastructure applications soil applications


The CPEC306 is a turn-key, closed-path eddy-covariance (EC) flux system for long-term monitoring of atmospheric-biosphere exchanges of carbon dioxide, water vapor, heat, and momentum. A complete system consists of a closed-path gas analyzer (EC155 closed-path gas analyzer), sonic anemometer (CSAT3A sonic anemometer), data logger (CR6 datalogger), sample pump, and accommodations for a CDM-A116 allowing for additional sensors.

The gas analyzer’s intake design and small sample cell volume (5.9 mL) provide excellent frequency response (4.3 Hz cutoff frequency) with low total system power (12 W). Additionally, the vortex intake (United States Patent No. 9,217,692) greatly reduces maintenance and maintains frequency response compared to traditional inline filters.

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Benefits and Features

  • Expandable, mid-level system with CR6 datalogger processing power
  • Suitable for sites with many sensors and either a short or tall tower
  • Simple design for easier troubleshooting


Main enclosure for the CPEC306
CPEC306 plumbing

Detailed Description

The gas analyzer’s small sample cell volume (5.9 mL) minimizes the sample residence time (50 ms at the system’s nominal flow rate, 7 LPM). This gives excellent frequency response (5.8 Hz half-power bandwidth) with low total system power (12 W).

Eddy-Covariance Measurements

CO2 and H2O are measured with an EC155 Closed-Path Gas Analyzer. Three-dimensional wind speed and sonic air temperature are measured with a CSAT3A sonic anemometer head.

CPEC306 System Enclosure

The CPEC306 has two enclosures: a fiberglass enclosure that houses the CR6 datalogger, pump module, and optional CDM-A116, and the EC100 enclosure for data processing.

CPEC306 Pump Module

The pump module, a standard component of the CPEC306 system, consists of a small dual-head diaphragm pump with a brushless dc motor mounted inside a fiberglass enclosure. An integral cable connects the pump module to the CPEC306 system enclosure, which provides power, temperature measurement and control, pressure measurement, and pumping speed measurement and control.


Operating Temperature Range -30° to +50°C
Input Voltage Range 10.5 to 16.0 Vdc
  • 12 W (typical)
  • 35 W (maximum, at cold startup)

System Enclosure

Dimensions 54 x 44.5 x 29.7 cm (21.3 x 17.5 x 11.7 in.)
  • 13.72 kg (30.25 lb)
  • 14.6 kg (32.2 lb) with optional CDM-A116 module

Pump Module

Inlet Connection 3/8-in. Swagelok
Pressure Sensor Range 15 to 115 kPa
Pumping Speed 3 to 9 LPM (automatically controlled at the set point, typically 7 LPM)


CR6 OS v.8.00 (6.87 MB) 06-27-2018

(WARNING) If updating the dataloggers operating system from a version prior to 7.0, the user will need to install updated USB drivers for the CR6. The new drivers are available in Device Configuration Utility version 2.16 (or greater) which is available on the Campbell Scientific website.

Execution of this download installs the Operating Systems for the CR6 and all integrated communication options to your computer. It also updates the CRBasic Editor compiler and support files. The Device Configuration Utility is used to upload the Operating Systems to the CR6.

Note: Upgrading the Operating System will reset all the CR6’s settings back to the factory defaults.  Sending this OS remotely is not recommended.  To restore settings after the update, it is recommended that a backup be made of the current logger settings or take programmatic measures to ensure your settings can be restored. This can be done using the DevConfig backup utility or CRBasic instruction SetSetting.

Watch the Video Tutorial: Sending an OS to a Local Datalogger.

View Update History

EC100 OS v.8.01 (561 KB) 05-07-2018

EC100 Operating System.

Watch the Video Tutorial: Updating the EC100 Operating System.

View Update History

ECMon v.1.6 (10.7 MB) 03-29-2016

EC100-Series Support Software.

Device Configuration Utility v.2.19 (33.2 MB) 12-06-2018

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 10, 8.1, 8, and 7 (Both 32 and 64 bit)

View Update History

EasyFlux DL for CR6CP v.1.01 (105 KB) 09-19-2018

CR6 datalogger program for Campbell closed-path eddy-covariance systems.

Frequently Asked Questions

Number of FAQs related to CPEC306: 5

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  1. No. A valve module is required to use the Scrub Module. Only the CPEC310 comes with a valve module.

  2. The bottles of sieve for drop-in replacement contain the pellets and a membrane on top. The membrane is necessary to keep the pellets contained while allowing gas to pass over the zeolite. The bottle has the same footprint as the old magnesium perchlorate bottles. The amount in each bottle is listed on the bottle. The amount of sieve needed for each analyzer is the following:

    • The EC150 needs 22 g (drop-in bottle).
    • The IRGASON® needs 22 g (drop-in bottle).
    • The EC155 needs 22 g (drop-in bottle).
    • The AP200 needs 500 g (refill).
    • The 27423 needs 1000 g (refill).
    • The 31022 needs 500 g (refill).
  3. The molecular sieve is a non-hazardous material that can be shipped to any country.

  4. The molecular sieve is a direct replacement for the old magnesium perchlorate bottles. The molecular sieve may be used for any Campbell Scientific analyzer that used the old bottles.

  5. The molecular sieve has been demonstrated here by our engineering department to be effective at removing CO2 and H2O from the air sample. The change was made for two reasons:

    1. It was a safer alternative than using the previous chemicals.
    2. Increased shipping regulations for the chemicals limited the number of suppliers. 

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