EC155 Closed-Path CO2/H2O Gas Analyzer
Now with Vortex Technology
Use as part of closed-path eddy-covariance system
weather applications supported water applications supported energy applications supported gas flux and turbulence applications supported infrastructure applications supported soil applications supported

Overview

Campbell Scientific's EC155 closed-path analyzer incorporates vortex technology for reduced maintenance, an absolute pressure sensor in the sample cell for more accurate measurements, and a sample cell with improved corrosion protection. The EC155 can be combined with the CSAT3A sonic anemometer, as shown in the main image. The revised CSAT3A has a more aerodynamic and rigid design.

The EC155 is ordered as part of a CPEC300-series system (CPEC300, CPEC306, or CPEC310), which also includes the sample pump, data logger, optional valve module, and optional scrub module to provide a zero air source. The EC155 with anemometer simultaneously measures absolute carbon dioxide and water vapor mixing ratio, sample cell temperature and pressure, and three-dimensional wind speed and sonic air temperature.

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Benefits and Features

  • Vortex Intake (U.S. Pat. No. 9,217,692) greatly reduces maintenance frequency compared to traditional in-line filters
  • Heated inlet increases protection against condensation
  • More accurate pressure measurements with the new sample cell absolute pressure sensor
  • Fully integrated, detachable intake
  • Improved corrosion protection with stainless-steel sample cell
  • Improved sonic temperature from more rigid CSAT3 geometry
  • Stream-lined, aerodynamic CSAT3A mounting
  • Slim aerodynamic shape with minimal wind distortion
  • Analyzer, sample cell, and sonic anemometer measurements have matched bandwidths and are synchronized by a common set of electronics
  • Low power consumption; suitable for solar power applications
  • Low noise
  • Small sample cell for excellent frequency response
  • Integrated zero/span connection for simplified field zero/span
  • Field rugged
  • Field serviceable
  • Factory calibrated over wide range of CO2, H2O, pressure and temperature in all combinations encountered in practice
  • Extensive set of diagnostic parameters
  • Fully compatible with Campbell Scientific data loggers; field setup, configuration, and field zero and span can be accomplished directly from the data logger
  • Rain: innovative signal processing and transducer wicks considerably improve performance of the anemometer during precipitation events

Technical Description

The EC155 has the following outputs:

  • Ux (m/s)*
  • Uy (m/s)*
  • Uz (m/s)*
  • Sonic Temperature (°C)*
  • Sonic Diagnostic*
  • CO2 Mixing Ratio (µmol/mol)
  • H2O Mixing Ratio (mmol/mol)
  • Gas Analyzer Diagnostic
  • Cell Temperature (°C)
  • Cell Pressure (kPa)
  • CO2 Signal Strength
  • H2O Signal Strength
  • Differential Pressure (kPa)
  • Source Temperature (°C)

*Requires a CSAT3A Sonic Anemometer Head.

Images

Specifications

Operating Temperature Range -30° to +50°C
Operating Pressure 70 to 106 kPa
Input Voltage Range 10 to 16 Vdc
Power 5 W (steady state and power up) at 25°C
Measurement Rate 60 Hz
Output Bandwidth 5, 10, 12.5, or 20 Hz (user-programmable)
Output Options SDM, RS-485, USB, analog (CO2 and H2O only)
Auxiliary Inputs Air temperature and pressure
EC100 Barometer Accuracy
  • ±1.5 kPa (> 0°C), increasing linearly to ±.3.7 kPa at -30°C (basic)
  • ±0.15 kPa (-30° to +50°C) (enhanced)
Sample Intake/Sonic Volume Separation 15.6 cm (6.1 in.)
Warranty 3 years or 17,500 hours of operation (whichever comes first)
Cable Length 3 m (10 ft) from EC155/CSAT3A to EC100
Weight
  • 3.9 kg (8.5 lb) for EC155 head and cables
  • 1.7 kg (3.7 lb) for CSAT3A head and cables
  • 0.4 kg (0.9 lb) for mounting hardware
  • 3.2 kg (7 lb) for EC100 electronics

Gas Analyzer
Sample Cell Thermistor Accuracy ± 0.15°C (-30° to +50°C)
Sample Cell Pressure Accuracy ± 1.5 kPa (> 0°C ), increasing linearly to ±3.7 kPa at -30°C

Gas Analyzer - CO2 Performance
Accuracy
  • Assumes the following: the gas analyzer was properly zero and spanned using the appropriate standards; CO2 span concentration was 400 ppm; H2O span dewpoint was at 12°C (16.7 ppt); zero/span temperature was 25°C; zero/span pressure was 84 kPa; subsequent measurements made at or near the span concentration; temperature is not more than ±6°C from the zero/span temperature; and ambient temperature is within the gas analyzer operating temperature range.
  • 1% (Standard deviation of calibration residuals.)
Precision RMS (maximum) 0.15 µmol/mol

Nominal conditions for precision verification test: 25°C, 86 kPa, 400 μmol/mol CO2, 12°C dewpoint, and 20 Hz bandwidth.
Calibrated Range 0 to 1,000 μmol/mol (0 to 3,000 µmol/mol available upon request.)
Zero Drift with Temperature (maximum) ±0.3 μmol/mol/°C
Gain Drift with Temperature (maximum) ±0.1% of reading/°C
Cross Sensitivity (maximum) ±1.1 x 10-4 mol CO2 /mol H2O

Gas Analyzer - H2O Performance
Accuracy
  • Assumes the following: the gas analyzer was properly zero and spanned using the appropriate standards; CO2 span concentration was 400 ppm; H2O span dewpoint was at 12°C (16.7 ppt); zero/span temperature was 25°C; zero/span pressure was 84 kPa; subsequent measurements made at or near the span concentration; temperature is not more than ±6°C from the zero/span temperature; and ambient temperature is within the gas analyzer operating temperature range.
  • 2% (Standard deviation of calibration residuals.)
Precision RMS (maximum) 0.006 mmol/mol

Nominal conditions for precision verification test: 25°C, 86 kPa, 400 μmol/mol CO2, 12°C dewpoint, and 20 Hz bandwidth.
Calibrated Range 0 to 72 mmol/mol (38°C dewpoint)
Zero Drift with Temperature (maximum) ±0.05 mmol/mol/°C
Gain Drift with Temperature (maximum) ±0.3% of reading/°C
Cross Sensitivity (maximum) ±0.1 mol H2O/mol CO2

Sonic Anemometer - Accuracy
-NOTE- The accuracy specification for the sonic anemometer is for wind speeds < 30 m s-1 and wind angles between ±170°.
Offset Error
  • < ±8.0 cm s-1 (for ux, uy)
  • < ±4.0 cm s-1 (for uz)
  • ±0.7° while horizontal wind at 1 m s-1 (for wind direction)
Gain Error
  • < ±2% of reading (for wind vector within ±5° of horizontal)
  • < ±3% of reading (for wind vector within ±10° of horizontal)
  • < ±6% of reading (for wind vector within ±20° of horizontal)
Measurement Precision RMS
  • 1 mm s-1 (for ux, uy)
  • 0.5 mm s-1 (for uz)
  • 0.025°C (for sonic temperature)
  • 0.6° (for wind direction)

Compatibility

Please note: The following shows notable compatibility information. It is not a comprehensive list of all compatible products.

Dataloggers

Product Compatible Note
CR1000 (retired)
CR1000X
CR200X (retired)
CR216X (retired)
CR3000
CR5000 (retired)
CR6
CR800 (retired)
CR850 (retired)
CR9000X (retired)

Downloads

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

EC100-Series Support Software.

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

FAQs for

Number of FAQs related to EC155: 8

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  1. Can molecular sieve be used in the future to replace bottles for gas analyzers sold before July 2017?

    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.

  2. Why does the EC155 require a barometer?

    The EC155 requires a barometer for several reasons. First, the EC155 calculates CO2 as a concentration, and these values must be multiplied by the air density to get the CO2 flux. Second, the closed-path analyzer measures the number of CO2 molecules in the path and converts them to a concentration. This conversion requires a measure of sample cell pressure, which in older EC155 models (serial numbers less than 2000) is the sum of the barometer and differential sensor. In newer EC155 models (serial numbers 2000 or greater), this conversion still requires a measure of sample cell pressure, but it is done with an absolute pressure sensor in the sample cell. Finally, the EC155 has been calibrated at the factory over a range of barometric pressures. 

  3. Which countries can the molecular sieve be shipped to?

    The molecular sieve is a non-hazardous material that can be shipped to any country.

  4. Why did Campbell Scientific start using molecular sieve? Does it have the same effect as the previously used chemicals?

    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. 
  5. How does the EC155 perform during precipitation?

    Precipitation can block the infrared beam of an open-path IRGA—primarily through accumulation on the windows and by falling through the measurement path. The EC155 is a closed-path IRGA that is protected from rainfall by taking its measurements within a sample cell assembly. Older EC155 models (serial numbers less than 2000) have a heated intake assembly with a rain diverter to prevent precipitation from entering the sample cell. Newer EC155 models (serial numbers 2000 and greater) have a heated inlet and vortex intake (U.S. Pat. No. 9,217,692), which significantly improve performance during precipitation events and in conditions of high particulate concentrations, such as dust storms. However, measurements from sonic anemometers can also be affected by rainfall, especially if droplets accumulate on transducer faces. Therefore, it is important to continue monitoring data during rainfall events to ensure quality measurements are included in final calculations of flux.

  6. Why was the EC155 design revised?

    Newer EC155 models (serial numbers 2000 and greater) take advantage of the new vortex intake technology (U.S. Pat. No. 9,217,692), which significantly reduces the frequency of maintenance required, especially in dustier, more polluted conditions. The new models also have an absolute pressure sensor instead of a differential one, which improves the pressure measurements. Finally, the new design uses a stainless-steel sample cell, which provides added protection against corrosion. 

  7. Where is there more information about open-path and closed-path gas analyzers?
  8. To prepare the molecular sieve, how many grams are needed per bottle?

    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).
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