EC150 CO2/H2O Open-Path Gas Analyser
Innovative Design
Use as part of open-path eddy-covariance systems or as a stand-alone IRGA
weather applications supported water applications supported energy applications supported gas flux & turbulence applications supported infrastructure applications supported soil applications supported

Overview

Campbell Scientific’s EC150 is an open-path analyser specifically designed for eddy-covariance flux measurements. As a stand-alone analyser, it simultaneously measures absolute carbon-dioxide and water-vapour densities, air temperature, and barometric pressure. With the optional CSAT3A sonic anemometer head, the EC150 also measures three-dimensional wind speed and sonic air temperature.

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Benefits and Features

  • Unique optical configuration gives a slim aerodynamic shape with minimal wind distortion
  • Analyzer and sonic anemometer measurements are synchronized by a common set of electronics
  • Maximum output rate of 60 Hz with 20 Hz bandwidth
  • Low power consumption; suitable for solar power applications
  • Low noise
  • Measurements are temperature compensated without active heat control
  • Angled windows to shed water and are tolerant to window contamination
  • 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 dataloggers; field setup, configuration, and field zero and span can be accomplished directly from the datalogger
  • Speed of sound determined from three acoustic paths; corrected for crosswind effects
  • Innovative signal processing and transducer wicks considerably improve performance of the anemometer during precipitation events

Images

EC150 gas analyzer head with updated CSAT3A (serial numbers 2000 or greater)
EC150 gas analyzer head with updated CSAT3A (serial numbers 2000 or greater)
EC150 gas analyzer head with updated CSAT3A (serial numbers 2000 or greater)
EC150 gas analyzer head with original CSAT3A (serial numbers less than 2000)
EC150 gas analyzer head
CM250 Boom Adapter
Example open-path eddy-covariance system based on an EC150; large enclosure holds a datalogger and power supply
EC150 gas analyzer head, CSAT3A (serial numbers less than 2000), and EC100 electronics mounted to a mast
Cable ports on bottom of EC100 enclosure
EC150 with CSAT3A (original design, serial numbers less than 2000) and mounting bracket
EC100 enclosure mounting, exploded view
EC150 gas analyzer head and IRGASON & EC150 Zero & Span Shroud mounted on IRGASON & EC150 Lab Stand
EC100 electronics panel
Angled, hydrophobic windows on the EC150 improved performance in rain

Technical Description

The CSAT3A has the following outputs:

  • Ux (m/s)*
  • Uy (m/s)*
  • Uz (m/s)*
  • Sonic Temperature (°C)*
  • Sonic Diagnostic*

The EC150 has the following outputs:

  • CO2 Density (mg/m3)
  • H2O Density (g/m3)
  • Gas Analyzer Diagnostic
  • Ambient Temperature (°C)
  • Atmospheric Pressure (kPa)
  • CO2 Signal Strength
  • H2O Signal Strength
  • Source Temperature (°C)

*The first five outputs require the CSAT3A Sonic Anemometer Head.

Specifications

Operating Temperature Range -30° to +50°C
Calibrated Pressure Range 70 to 106 kPa
Input Voltage Range 10 to 16 Vdc
Power 5 W (steady state and power up) at 25⁰C
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
Gas Analyzer/Sonic Volume Separation 5.0 cm (2.0 in.)
Warranty 3 years or 17,500 hours of operation (whichever comes first)
Cable Length 3 m (10 ft) from EC150 and CSAT3A to EC100
Weight
  • 2.0 kg (4.4 lb) for EC150 head and cables
  • 1.7 kg (3.7 lb) for CSAT3A head and cables
  • 3.2 kg (7.1 lb) for EC100 electronics

Gas Analyzer

Path Length 15.37 cm (6.05 in.)
A temperature of 20°C and pressure of 101.325 kPa was used to convert mass density to concentration.

Gas Analyzer - CO2 Performance

-NOTE- A temperature of 20°C and pressure of 101.325 kPa was used to convert mass density to concentration.
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) 0.2 mg/m3 (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/mole available upon request.)
Zero Drift with Temperature (maximum) ±0.55 mg/m3/°C (±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

-NOTE- A temperature of 20°C and pressure of 101.325 kPa was used to convert mass density to concentration.
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) 0.004 g/m3 mmol/mol (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) ±0.037 g/m3/°C (±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

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)
Speed of Sound Determined from 3 acoustic paths (corrected for crosswind effects)
Rain Innovative ultrasonic signal processing and user-installable wicks considerably improve the performance of the anemometer under all rain events.

Ambient Temperature

Manufacturer BetaTherm 100K6A1IA
Total Accuracy ±0.15°C (-30°C to +50°C)
EC100 ingress protection IP65

Compatibility

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

Dataloggers

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

Downloads

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

EC100-Series Support Software.

FAQs for

Number of FAQs related to EC150: 21

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

  2. 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.

  3. 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. 
  4. 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).
  5. The factory calibration accounts for CO2 and H2O signal strengths down to 0.7. Therefore, to ensure quality data, windows should be cleaned before signal strengths drop below 0.7. 

  6. Yes. A fine-wire thermocouple, such as a FW05, can be used.

  7. The power requirement for the IRGASON® or EC150 with CSAT3A is 5 W at room temperature regardless of whether it is powering up or under steady-state operation.  At extreme cold or hot temperatures, the power requirement reaches 6 W.

  8. The barometer and temperature sensor are needed because the IRGASON® and EC150 have been calibrated at the factory over a range of temperatures (-30° to +50°C) and barometric pressures (70 to 106 kPa). 

  9. The EC150 and IRGASON® can report a negative water concentration if enough liquid water accumulates on the optical windows. This is because the absorption spectrum of liquid water differs from that of water vapor. Typically, large rain droplets do not cause this phenomenon. Rather, misty or condensing conditions, which create a water film across the entire optical window, can cause this phenomenon. After the water film evaporates, the former measurement accuracy will be restored.  

    The IRGASON® and EC150 may also experience some amount of drift over time. If conditions are relatively dry and it has been a long time since a zero and span has been performed on the analyzer, it is possible to report a negative water vapor concentration. In this situation, perform a zero and span of the analyzer.  

  10. The minimum height for the IRGASON® or EC150 should be approximately 2 m. Sensor placement below that height may result in a significant loss in frequency response. The maximum height depends on the available upwind fetch or footprint area.  As a general guideline for unstable boundary layer conditions, the height of the sensor should be less than the distance from the sensor to the outermost edge of the footprint area divided by one hundred. For example, if there is 500 m of available upwind fetch, the IRGASON® or EC150 should not exceed a height of 5 m.  Note that for neutral and stable conditions, the footprint area will grow.


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