INSTRUCTION MANUAL IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer Revision: 6/14 C o p y r i g h t © 2 0 1 0 - 2 0 1 4 C a m p b e l l S c i e n t i f i c , I n c .
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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.
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 5. Specifications .....
Table of Contents 9. Maintenance ..............................................................25 9.1 9.2 9.3 9.4 9.5 9.6 Routine Maintenance......................................................................... 25 Wick Maintenance............................................................................. 25 9.2.1 Sonic Wicks ............................................................................... 25 9.2.2 Gas Analyzer Wicks ...................................................................
Table of Contents 9-1. 9-2. 9-3. 9-4. 9-5. 9-6. A-1. A-2. Proper location of the sonic top wick (left) and bottom wick (right) .............................................................................................. 26 PN 28902 CSAT3 Sonic Wick Spares Kit contents ........................... 26 Proper location of the gas analyzer top wick (left) and bottom wick (right) .....................................................................................
Table of Contents iv
IRGASON® Integrated CO2/H2O OpenPath Gas Analyzer and 3D Sonic Anemometer 1. Introduction The IRGASON, U.S. Des. Patent No. D680455, is an in-situ, open-path, midinfrared absorption gas analyzer integrated with a three-dimensional sonic anemometer. The gas analyzer provides measurements of absolute densities of carbon dioxide and water vapor, while the sonic anemometer measures orthogonal wind components.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer o o o 3. The SDM, USB, and RS-485 output options include IRGASON diagnostic data. Be aware that the absence of diagnostic data in the analog output option could make troubleshooting difficult and may lead to the user not being aware of potential problems with the instrumentation (see Section 8, EC100 Outputs). Resting the analyzer on its side during the zero-and-span procedure may result in measurement inaccuracy.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer These measurements are required to compute carbon dioxide and water vapor fluxes using the: • Standard outputs: o ux, uy, and uz orthogonal wind components o sonic temperature (based on the measurement of c, the speed of sound) o sonic diagnostic flags o CO2 density, H2O density o gas analyzer diagnostic flags o air temperature, air pressure o CO2 signal strength, H2O signal strength o Air temperature and air pressure are auxiliary
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer Sonic accuracy5 Offset error < ±8 cm·s–1 ux, uy: < 4 cm·s–1 u z: Gain error Wind vector ±5° horizontal: < ±2% of reading Wind vector ±10° horizontal: < ±3% of reading Wind vector ±20° horizontal: < ±6% of reading Sonic reporting range Full scale wind: Sonic temperature: ±65.553 m/s –50° to +60°C Auxiliary sensors6 Barometer Basic barometer Accuracy –30 to 0°C: ±3.7 kPa at –30°C, falling linearly to ±1.5 kPa at 0oC 0° to 50°C: ±1.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer 5.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer FIGURE 5-1. IRGASON dimensions, side view FIGURE 5-2.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer 5.4 Power Requirements During Power-up and Operation Power requirement Source: 10 to 16 Vdc Load 420 mA at 25oC: at 25oC in power-down mode1: 250 mA 1 6. sonic anemometer fully powered and gas analyzer in stand-by Installation 6.1 Orientation During operation, the IRGASON should be leveled and pointed into the prevailing wind to minimize flow distortions from the instrument arms and other supporting structures.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer WARNING 8 Handle the IRGASON carefully. The optical source may be damaged by rough handling, especially while the analyzer is powered. 6. If the assembly is not level, slightly loosen the bolt that holds the mounting bracket on the boom adapter and adjust the assembly until the leveling bubble on top of the IRGASON block is within the bullseye. Retighten the bolt. 7.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer IRGASON IRGASON Mounting Bracket (pn 27496) CM250 Leveling Mount (pn 26559) CM20X (pn 1790X) or equivalent crossarm FIGURE 6-1. Exploded view of mounting the IRGASON WARNING Over-tightening bolts will damage or deform the mounting hardware.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer FIGURE 6-2. EC100-enclosure mounting bracket mounted on a vertical mast (left) and a tripod leg (right) FIGURE 6-3.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer 8. Mount the IRGASON temperature probe so that it measures temperature at the same height as the sample volume of the IRGASON. To do this, first attach the R.M. Young 41303-5A 6-Plate Solar Radiation Shield (pn 4020) to the mast with the included u-bolt. Next, insert the end of the probe into the hole on the bottom of the shield. Tighten the screws to hold the probe in place. See FIGURE 6-4.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer 2. Connect the IRGASON sonic cable. Similar to (a), begin by removing the black- rubber cable-entry plug found on the bottom left of the EC100 enclosure. Insert the cable entry plug on the cable into the slot and connect the male end to the female connector labeled Sonic Anemometer on the EC100 electronics (see FIGURE 6-5). The sonic cable is approximately 3 meters in length. FIGURE 6-5.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer FIGURE 6-6. Base of EC100 enclosure NOTE Unique calibration information is stored in the gas and sonic connectors of the IRGASON rather than in the EC100. This means that any IRGASON may be used with any EC100. FIGURE 6-7.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer 3. Connect the IRGASON temperature probe. Unscrew the temperature connector cover, which is found on the base of the EC100 enclosure (see FIGURE 6-6). Insert the 3-prong probe connector into the female connector on the enclosure and screw it firmly in place. The IRGASON temperature probe cable is approximately 3 meters in length. 4. Ground the EC100 by attaching a thick wire (e.g.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer o 7. Analog output: use cable CABLE4CBL-L (pn 21972) or CABLE2TP-L (pn 26986-L). Once again, the customer specifies the length of this cable at time of order. The connector labeled Analog Outputs on the EC100 panel indicates where each wire should be connected (CO2 voltage signal, H2O voltage signal, and two ground connections). 6. Wire power and ground (i.e., power reference) cable CABLEPCBL-L (pn 21969-L) to the EC100.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer 7.1 Factory Defaults TABLE 7-1 shows the default value for each setting described in the following sections. TABLE 7-1. Factory Default Settings 7.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer any integer value between 0 and 14. The value 15 is reserved as an SDM-group trigger. 7.4 Unprompted Output If the EC100 is to output data as USB or RS-485 (see Section 8.2, USB or RS-485 Output), this setting must be set to USB Port or RS485, respectively. The factory default is to disable the unprompted output and assume data are to be logged via SDM (see Section 8.1, SDM Output). Only one unprompted-output type (i.e.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer 7.11 Pressure Sensor This setting identifies which barometric pressure sensor is used. The EC100 always includes the basic barometer, but it may be ordered with the optional enhanced barometer (model CS106). This setting defaults to EC100 Enhanced if the CS106 is ordered and to EC100 Basic otherwise. There are two other possible settings for Pressure Sensor. First, the user may supply a different pressure sensor.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer The algorithm uses the internal heaters to maintain a temperature that is a couple of degrees above the ambient dewpoint (or frost point) to prevent condensation and icing from forming on the surface of the optical windows.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer Besides changing settings, ECMon is a useful tool for common tasks such as: • • • Monitoring real-time data from the IRGASON from the main window Performing manual zero and span of the instrument (see Section 9.4, Zero and Span) Troubleshooting and monitoring diagnostics using the Status window. FIGURE 7-1.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer FIGURE 7-2. Setup window in ECMon 7.15 Device Configuration Utility DevConfig software (Device Configuration Utility) may also be used to change settings, although ECMon is generally preferred because of its more user-friendly interface. DevConfig may be downloaded from the IRGASON, EC150 & EC155 Support CD (pn 27007), or may be downloaded free of charge from the Campbell Scientific website www.campbellsci.com).
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer 8. EC100 Outputs The EC100 is the IRGASON electronics module that measures the sensors and controls the system. It outputs data in one of four types: SDM, USB, RS-485, or analog. In general, Campbell Scientific recommends that SDM be used if a Campbell Scientific datalogger is responsible for data collection. However, RS-485 output is recommended if cable lengths exceed 100 meters.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer To use USB or RS-485 output, connect a USB or RS-485 cable from the EC100 to the receiving device (see Section 6.3, Wiring and Connections), and configure the settings (see Section 7, Settings). The Unprompted Output setting must be set to USB or RS-485. If RS-485 is selected, the RS485 Baud Rate must be set. The Unprompted Output Rate must be set to the desired output rate. All output data are formatted as comma delimited ASCII.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer The final data element in each row or output array is the signature. The signature is a four character hexadecimal value that is a function of the sequence and number of bytes in the output array. The recording device (i.e., PC or datalogger) calculates its own signature using each transmitted byte until encountering the transmitted signature. The computed signature and the transmitted signature are compared.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer TABLE 8-2. Multipliers and Offsets for Analog Outputs 9. Density (mg m-3) Voltage Output Multiplier (mg m-3 V-1) Offset (mg m-3) CO2 386.32 -102.59 H2O 8.65 -2.26 Maintenance IRGASON operation requires six maintenance tasks: • • • • • • 9.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer Wick Spares Kit (pn 28902) consists of three top wicks, three bottom wicks, adhesive, and an installation tool (see FIGURE 9-2). The installation tool is used by placing a wick over the angled end of the tool, placing the straight end of the tool gently against the transducer face, and sliding the wick down the tool onto the transducer. When installing wicks, be sure they are located in the proper position.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer 9.2.2 Gas Analyzer Wicks IRGASON gas analyzer windows are polished and slanted at an angle to prevent water from collecting on their surfaces. However, due to increased surface tension at the interface with the snout, water can pool at the edges and partially block the optical path and attenuate the signal. To minimize the occurrence of such events and the resulting data loss, consider using wicks.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer FIGURE 9-3. Proper location of the gas analyzer top wick (left) and bottom wick (right) 9.3 Gas-Analyzer Window Cleaning The windows of the analyzer should be cleaned if the signal strength for CO2 or H2O drops below 0.7 or 70% of the original value. These values may be monitored in the output data, or they can be viewed with ECMon.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer The first part of the following procedure simply measures the CO2 and H2O zero and span, without making adjustments. This allows the CO2 and H2O gain factors to be calculated. These gain factors quantify the state of the analyzer before the zero-and-span procedure, and in theory could be used to correct recent measurements for drift.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer Intake Thermistor Cable Exhaust FIGURE 9-4. The zero-and-span shroud mounted on the zero-andspan stand. The top tube is the gas intake, the black cable is the temperature thermistor, and the short bottom tube is the gas exhaust. 30 4. Disconnect the IRGASON temperature sensor from the EC100 and connect the shroud temperature sensor in its place. 5. Connect the EC100 to a PC with the EC100 USB cable (pn 26563). 6.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer NOTE Use mixtures of CO2 and ambient air for the CO2 span gas. The use of reference CO2 gas mixtures in pure nitrogen will lead to errors due to a carrier gas effect on pressure-broadening of the CO2 absorption lines since oxygen gas has a smaller line-broadening coefficient than nitrogen. FIGURE 9-5. ECMon zero-and-span window 9.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer 11. Examine the measurements that were written down for span CO2, span H2O, and zero air. Compute the drift in instrument gain using the following equation: gain = spanactual spanmeas − zeromeas where, • • • spanactual = known concentration of the span gas spanmeas = measured concentration of the span gas zeromeas = measured concentration in zero gas.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer excessively (see Section 9.4, Zero and Span), the bottles should be replaced. To do this, twist the scrubber-bottle covers of the upper and lower arms counter-clockwise until they detach (they should loosen by hand). Remove the IRGASON chemical bottles (pn 26510) from inside the covers, and replace them with new bottles lid-first (see FIGURE 9-6). Once this is done, firmly screw the covers back on the arms.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer Monitoring Division / National Oceanographic and Atmospheric Administration in Boulder, CO, USA. After an extended period of time in the field, the IRGASON gas analyzer may need to undergo this factory calibration again to ensure valid measurements. When recalibration is deemed necessary, contact Campbell Scientific. The IRGASON sonic anemometer also undergoes an initial factory calibration.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer TABLE 10-1. Output Modes for EC100 Instruction Output Mode 0, 1, 2, 1, 2 Data Field Description Units 1 Ux m/s 2 Uy m/s 3 Uz m/s 4 Sonic Temperature ºC 5 Sonic Diagnostic Flag 6 CO2 Density mg/m3 7 H2O Density g/m3 8 Gas Diagnostic Flag 9 Air Temperature ºC 10 Air Pressure kPa CO2 Signal Strength nominally 0.0 ≤ strength ≤1.0 H2O Signal Strength nominally 0.0 ≤ strength ≤1.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer TABLE 10-3.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer 10.2 EC100Configure() Instruction EC100Configure() provides a third option, beside the ECMon software and DevConfig utility, for retrieving and modifying settings. ECmon and Device Configuration are user-interactive, whereas the EC100Configure() instruction allows automated control under CRBasic datalogger programming. EC100Configure() is a processing instruction.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer TABLE 10-4. ConfigCmd Values for Setting and Retrieving Settings ConfigCmd Variable Set Retrieve Setting Description (some settings list possible values for the DestSource variable) 0 100 Bandwidth: 5 = 5 Hz, 10 = 10 Hz, 12 = 12.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer 10.2.1 ConfigCmd 11 Zero-and-span Control To perform zeroing of CO2 and H2O , ConfigCmd 11 is set to 1. After the IRGASON completes the zero, it will write the value to -1. The datalogger program can poll this value or simply wait for a period of time to allow the zeroing to complete.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer output indicates moisture is present, the datalogger can send the EC100Configure() instruction to the IRGASON and enable the heaters. 10.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer 11. Theory of Operation 11.1 IRGASON Sonic Anemometer The CSAT3 measures wind speeds and the speed of sound by determining the time of flight of sound between pairs of transducers. However, unlike many other commercial anemometers, it does not use simple threshold detection to determine the ultrasonic times of flight.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer 11.1.2 Temperature The sonically determined speed of sound can be found from the sum of the inverses of Eq. (1) and (2). The CSAT3 corrects online for the effect of wind blowing perpendicular to the sonic path. No additional off-line corrections are required as suggested by Liu et al., 2001.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer The sonic virtual temperature, in degrees Celsius, is given by Eq. (9), where γd = 1.4 and Rd = 287.04 J·K-1·kg-1. Ts = c 2 γ dRd − 273.15 (9) 11.2 IRGASON Gas Analyzer The IRGASON gas analyzer is a non-dispersive mid-infrared absorption analyzer. Infrared radiation is generated in the upper arm of the analyzer head before propagating along a 15 cm optical path.
IRGASON® Integrated CO2/H2O Open-Path Gas Analyzer and 3D Sonic Anemometer 11.3 Theory References Kaimal, J. C. and Businger, J. A.: 1963, “A Continuous Wave Sonic Anemometer-Thermometer”, J. Applied Meteorol., 2, 156-164. Kaimal, J. C. and Gaynor, J. E.: 1991, “Another Look at Sonic Thermometry”, Boundary-Layer Meteorol., 56, 401-410. Fleagle, R. G. and Businger, J. A.: 1980, An Introduction to Atmospheric Physics, Academic Press, Inc., New York. Liu, H., Peters, G., and Foken, T.
Appendix A. Filter Bandwidth and Time Delay The EC100 measures CO2, H2O, 3-D wind components, and sonic temperature from the IRGASON at 100 Hz and then applies a user-selectable low-pass filter. The available filter bandwidths are 5, 10, 12.5, 20, and 25 Hz. FIGURE A-1 shows the amplitude response of these filters. The EC100 filters provide a flat pass band, a steep transition from pass band to stop band, and a wellattenuated stop band.
Appendix A. Filter Bandwidth and Time Delay The EC100 measures gas and wind data at 100 Hz, and 100 Hz data are downsampled to the datalogger scan rate through SDM communications (see Section 8, EC100 Outputs). This process synchronizes EC100 gas and wind data with other signals measured by the datalogger to within ±5 ms (plus or minus onehalf of the inverse of 100 Hz).
Appendix A. Filter Bandwidth and Time Delay EC100 10-Hz Filter Compared to 20-msec Moving Average (Amplitude Responses) 10 1 No Units 0.1 EC100 10-Hz Bandwidth Filter 10-Hz Bandwidth from a 50-msec Moving Average 0.01 0.001 0.0001 1 10 70 Hertz FIGURE A-2. Frequency response comparison of the EC100 10 Hz bandwidth and a 50 ms moving average TABLE A-1. Filter Time Delays for Various Bandwidths Bandwidth (Hz) Time Delay (ms) 5 800 10 400 12.
Appendix A.
Appendix B. Equations TABLE B-1 lists variables and constants used in the following equations. TABLE B-1. Table of Equation Variables and Constants Variable or Constant Description Units ρc CO2 Mass Density mg·m-3 ρv H2O Mass Density g·m-3 ρd Mass Density of Dry Air g·m-3 Xc Xv CO2 Molar Mixing Ratio (concentration relative to dry air) H2O Molar Mixing Ratio (concentration relative to dry air) Mc Molecular Weight of CO2 44 mg·mmol-1 Md Molecular weight of dry air 0.
Appendix B. Equations PM X d v 1 − ρ d = ( ) + + R T 273 . 15 1000 X v (B-5) Dew Point from Molar Mixing Ratio Td = 240.97 Td _ tmp (B-62) 17.502 − Td _ tmp XvP Td _ tmp = ln 0.61121 ⋅ f (1000 + X v ) ( (B-72) ) ) ( f = 1.00072 + 3.2 ×10 −5 P + 5.9 ×10 −9 PT 2 (B-82) Water Vapor Molar Mixing Ratio from Dew Point Xv = e 1000 P−e (B-9) 17.502Td e = 0.61121 ⋅ f ⋅ EXP 240.
Appendix C. Material Safety Data Sheets (MSDS) MSDS are available for chemicals used in IRGASON filters. The MSDS samples below are made available for convenience. However, chemical manufacturers may change MSDS at any time. Up-to-date MSDS are available at www.campbellsci.com. C.
Appendix C. Material Safety Data Sheets (MSDS) C.
Appendix C.
Appendix C.
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