INSTRUCTION MANUAL EC155 CO2 and H2O Closed-Path Gas Analyzer 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 7.4 Device Configuration Utility ............................................................. 23 8. EC100 Outputs ..........................................................23 8.1 8.2 8.3 SDM Output ...................................................................................... 23 USB or RS-485 Output...................................................................... 24 Analog Outputs.................................................................................. 26 9.
Table of Contents 6-2. 6-3. 6-4. 6-5. 6-6. 7-1. 7-2. 7-3. 8-1. 9-1. 9-2. 9-3. 9-4. 9-5. 9-6. 9-7. 9-8. A-1. A-2. EC100 enclosure mounting bracket mounted on a vertical mast (left) and a tripod leg (right) ........................................................... 10 Exploded view of mounting the EC100 enclosure ............................. 11 End views of the analyzer showing the sample intake (optional heated intake not shown), pump outlet, and zero-and-span intake .....................................
Table of Contents iv
EC155 CO2 and H2O Closed-Path Gas Analyzer 1. Introduction The EC155 is an in-situ, closed-path, mid-infrared absorption gas analyzer that measures molar mixing ratios of carbon dioxide and water vapor, along with sample cell temperature and pressure. The EC155 may be used in conjunction with the CSAT3 sonic anemometer, which measures orthogonal wind components.
EC155 CO2 and H2O Closed-Path Gas Analyzer • 3. CAUTION: o Grounding the EC100 measurement electronics is critical. Proper grounding to earth (chassis) will ensure maximum ESD (electrostatic discharge) protection and improve measurement accuracy. o Do not connect or disconnect the gas analyzer or sonic connectors while the EC100 is powered. o The SDM, USB, and RS-485 output options include EC155 diagnostic data.
EC155 CO2 and H2O Closed-Path Gas Analyzer 5. Specifications 5.
EC155 CO2 and H2O Closed-Path Gas Analyzer Factory calibrated range CO2: H2O: Analyzer temp: Baro pressure: 0 to 1000 µmol·mol-1 0 mmol·mol-1 to 37oC dewpoint -30o to 50oC 70 to 106 kPa CO2 performance Zero max drift3: Gain Drift: Sensitivity to H2O: ±0.55 mg·m-3·°C-1 (±0.3 μmol·mol·°C-1) ±0.1% of reading·°C-1 (maximum) ±5.6 x 10-5 µmol CO2·mol-1 H2O (max) H2O performance Zero max drift3: Gain Drift: Sensitivity to CO2: ±0.037 g·m-3·°C-1 (±0.05 mmol·mol-1·°C-1) ±0.3% of reading·°C-1 (maximum) ±0.
EC155 CO2 and H2O Closed-Path Gas Analyzer 5.2 1 noise rms, assumes: o 25°C o 85 kPa o 19 mmol/mol H2O concentration o 326 mmol/mol CO2 concentration o 25 Hz bandwidth.
EC155 CO2 and H2O Closed-Path Gas Analyzer 5.3 Physical Description Sample cell volume: 5.9 cm3 (0.36 in3) Sample cell length: 12.0 cm (4.72 in) Sample cell diameter: 7.94 mm (0.313 in) Spatial separation between EC155 optional intake and CSAT3A sample volume: 15.6 cm (6.1 in) Length of tubing from tip of optional heated intake to sample cell: 58.4 cm (23 in) Inside diameter of intake tubing: 2.67 mm (0.
EC155 CO2 and H2O Closed-Path Gas Analyzer FIGURE 5-1. Dimensions of EC155 analyzer head with optional heated intake FIGURE 5-2.
EC155 CO2 and H2O Closed-Path Gas Analyzer 5.4 Power Requirements Voltage supply: 10 to 16 Vdc Power at 25oC including CSAT3A: 4.8 W Power at 25oC excluding CSAT3A: 4.0 W 6. Power at 25oC in power-down mode (CSAT3A fully powered and EC155 in stand-by): 3.0 W Power for optional heated intake: set by user, 0 to 0.7 W. Installation 6.1 Mounting The EC155 is supplied with mounting hardware to attach it to the end of a horizontal pipe of 1.
EC155 CO2 and H2O Closed-Path Gas Analyzer f. Level the assembly by slightly loosening the bolt in the CM250 leveling mount. Adjust the assembly until the leveling bubble on top of the CSAT3A is in the bullseye. Retighten the bolt. WARNING Over-tightening bolts will damage or deform the mounting hardware. WARNING Use caution when handling the EC155 gas analyzer. The optical source may be damaged by rough handling, especially when the EC155 is powered.
EC155 CO2 and H2O Closed-Path Gas Analyzer NOTE The CSAT3A sonic anemometer is an updated version of the CSAT3, designed to work with the EC100 electronics. An existing CSAT3 may be upgraded to a CSAT3A. Contact Campbell Scientific for details. g. Attach the EC100 electronic enclosure to the mast, tripod leg, or other part of the mounting structure. To do this, attach the EC100 enclosure mounting bracket (pn 26604) to the pipe by loosely tightening the u-bolts around the pipe.
EC155 CO2 and H2O Closed-Path Gas Analyzer FIGURE 6-3. Exploded view of mounting the EC100 enclosure h. 6.2 Remove the EC100 enclosure desiccant from the plastic bag and put it back in the mesh pocket of the enclosure. Adhere the humidity indicator card to the inside of the enclosure. Plumbing 6.2.1 Flow The EC155 has a small sample cell volume (5.9 cm3) to give good frequency response at a relatively low flow rate. The sample cell residence time is 50 ms for a nominal 7 LPM flow.
EC155 CO2 and H2O Closed-Path Gas Analyzer The pressure drop in the optional heated intake assembly is approximately 2.5 kPa at 7 LPM flow with no filter. The filter adds approximately 1 kPa pressure drop when it is clean. This pressure drop will increase as the filter clogs. The filter should be replaced before the differential pressure reaches -7 kPa (unless the user has supplied a pressure sensor with a wider range). See Section 9.2, Intake Filter Replacement for details on replacing the filter.
EC155 CO2 and H2O Closed-Path Gas Analyzer Analyzer Head Cable Sample Cell Cable FIGURE 6-4. End views of the analyzer showing the sample intake (optional heated intake not shown), pump outlet, and zero-and-span intake 6.2.4.1 Sample Intake The EC155 can be ordered with a factory-installed intake assembly, or with a Swagelok fitting to attach a user-supplied intake assembly. If the EC155 is configured with the intake assembly, it is installed at the factory. No further assembly is required.
EC155 CO2 and H2O Closed-Path Gas Analyzer module. During zero and span the zero or span gas can be pushed into this fitting to flow backward through the sample cell and exhausted through the intake assembly. NOTE 6.3 The CPEC200 system includes a valve module controlled by a CR3000 datalogger, which automates the zero gas and CO2 span gas flows during the zero-and-span procedure.
EC155 CO2 and H2O Closed-Path Gas Analyzer FIGURE 6-6. Bottom of EC100 enclosure CAUTION Do not connect or disconnect the EC155 gas analyzer head or CSAT3 sonic head while the EC100 is powered. a. Connect the EC155 gas analyzer head. Begin by removing the black rubber cable entry plug (pn 26224) on the bottom right of the EC100 enclosure. (This plug can be stored in the mesh pocket of the enclosure).
EC155 CO2 and H2O Closed-Path Gas Analyzer NOTE Unlike previous models of the CSAT3 3D sonic anemometer, the CSAT3A sonic head and the EC155 gas analyzer head have embedded calibration information. This means that any CSAT3A and any EC155 may be used with any EC100. d. CAUTION Ground the EC100 by attaching a thick wire (e.g., 12 AWG) to the grounding lug found on the bottom of the EC100 enclosure. The other end of the wire should be connected to earth (chassis) ground (i.e., grounding rod).
EC155 CO2 and H2O Closed-Path Gas Analyzer 7. f. Wire power and ground (i.e., power reference) cable CABLEPCBL-L (pn 21969-L) to the EC100. Feed the cable through one of the cable port openings in the bottom of the EC100 enclosure and attach the ends into the green EC100 power connector (pn 3768). Plug the connector into the female power connector on the EC100 panel. Ensure that the power and ground ends are going to the appropriate terminals labeled 12V and ground, respectively. g.
EC155 CO2 and H2O Closed-Path Gas Analyzer 7.2 Details This section gives an explanation for each setting. 7.2.1 SDM Address This parameter must be set to use SDM output from the EC100. See Section 8.1, SDM Output for details on using SDM output. Each SDM device on the SDM bus must have a unique address. The EC155 has a factory default SDM address of 1, but may be changed to any integer value between 0 and 14. The value 15 is reserved as an SDM group trigger. 7.2.
EC155 CO2 and H2O Closed-Path Gas Analyzer 7.2.5 RS-485 Baud Rate If the unprompted output mode is set to RS-485, this parameter determines the baud rate. Otherwise this setting is not used. The RS-485 baud rate defaults to 115200 bps, although the user may enter another value. 7.2.6 Analog Output The EC100 has two analog outputs for CO2 and H2O molar mixing ratios (see Section 8.3, Analog Outputs for more information). These outputs may be enabled/disabled with this setting.
EC155 CO2 and H2O Closed-Path Gas Analyzer The final option is to select None for the Pressure Sensor setting. The EC100 will use a fixed (see below) value for pressure. This mode is intended for troubleshooting only. 7.2.10.1 Pressure Gain If the Pressure Sensor is set to User Supplied, this setting gives the gain factor (kPa/V) used to convert measured voltage to pressure. Normally the Pressure Sensor is set to EC100 Basic or EC100 Enhanced, and this setting is not used. 7.2.10.
EC155 CO2 and H2O Closed-Path Gas Analyzer Besides changing settings, ECMon is also a useful tool for other common tasks such as: • • • Monitoring real-time data from the EC155 using the Display window Performing a manual zero and span of the instrument (see Section 9.4, Zero and Span) Troubleshooting and monitoring diagnostics using the Status window (see FIGURE 7-3). FIGURE 7-1.
EC155 CO2 and H2O Closed-Path Gas Analyzer FIGURE 7-2. The Setup window in ECMon FIGURE 7-3.
EC155 CO2 and H2O Closed-Path Gas Analyzer 7.4 Device Configuration Utility The Device Configuration Utility software may also be used to change settings, although ECMon is generally preferred because of its more user-friendly interface. Device Configuration may be downloaded from the EC150 & EC155 Support CD (pn 27007), or may be downloaded free of charge from the Campbell Scientific website in the Support|Downloads section (www.campbellsci.com/downloads).
EC155 CO2 and H2O Closed-Path Gas Analyzer dataloggers, the SDM protocol uses SDM-dedicated ports SDM-C1, SDM-C2, and SDM-C3. Each SDM device on the SDM bus must have a unique address. The EC155 has a factory default SDM address of 1, but may be changed to any integer value between 0 and 14 (see Section 7.2.1, SDM Address). The sample rate for SDM output is determined by the inverse of the datalogger scan interval, as set by the user in the datalogger program.
EC155 CO2 and H2O Closed-Path Gas Analyzer TABLE 8-1. USB and RS-485 Output Elements Data Element 1 2 3 4 5 6 7 8 9 10 11 12 Description Units/comments m/s m/s m/s °C 14 Ux Uy Uz Sonic Temperature Sonic Diagnostic Flag CO2 Concentration H2O Concentration Gas Diagnostic Flag Air Temperature Air Pressure CO2 Signal Strength H2O Signal Strength Sample Cell Pressure Differential Counter 15 Signature 13 µmol/mol mmol/mol °C kPa Nominally 0.0 to 1.0 Nominally 0.0 to 1.
EC155 CO2 and H2O Closed-Path Gas Analyzer The following block of code is an example implementation of Campbell Scientific’s signature algorithm in the programming language C. To generate the signature of an output array of bytes, the seed needs to be initialized to 0xaaaa and a pointer passed to the first byte of the output array. The number of bytes in the output array should be entered in as the swath. The returned value is the computed signature. //signature(), signature algorithm.
EC155 CO2 and H2O Closed-Path Gas Analyzer by heating in an oven. See the manual ENC10/12, ENC12/14, ENC14/16, ENC16/18, available at www.campbellsci.com, for more details on recharging desiccant bags. • 9.2 Make sure the Power and Gas LED status lights on the EC100 panel are green. If not, verify that all sensors are connected securely and that the instruments are powered. Also check the individual diagnostic bits for the specific fault. See TABLE 10-2 and TABLE 10-3.
EC155 CO2 and H2O Closed-Path Gas Analyzer Santoprene Tab FIGURE 9-1. The underside of the optional heated intake 9.3 Cleaning Analyzer Windows The windows of the analyzer should be cleaned if the signal strength of CO2 or H2O drops below 80% of the original value. (These values may be monitored in the output data, or they can be viewed with ECMon.) To clean the windows, follow these steps: 28 a. Stop the air flow through the EC155. b.
EC155 CO2 and H2O Closed-Path Gas Analyzer Thumbscrew Top Shell Thumbscrew Cable Clamp Thumbscrew FIGURE 9-2. The EC155 analyzer with the top shell open FIGURE 9-3. By loosening the thumbscrews above the sample cell, the latches may be spun from position A to position B, thus freeing the struts of the analyzer.
EC155 CO2 and H2O Closed-Path Gas Analyzer FIGURE 9-4. The EC155 analyzer and sample cell with shell top open Optical Window O-ring Optical Window O-ring FIGURE 9-5.
EC155 CO2 and H2O Closed-Path Gas Analyzer 9.4 Zero and Span As is the case with optical instrumentation, the EC155 may drift slightly with exposure to natural elements. Thus, a zero-and-span procedure should be performed occasionally. The first part of the procedure listed below simply measures the CO2 and H2O span and zero, without making any adjustments. This allows the CO2 and H2O gain factors to be calculated.
EC155 CO2 and H2O Closed-Path Gas Analyzer f. 1. Connect the zero-and-span gas to the Sample inlet, and disconnect the pump, leaving the Pump connection open. The zero-and-span gas will be pushed forward through the EC155 sample cell and exhausted out the Pump fitting. In this case the Zero/Span connection may be left plugged. 2. Connect the zero-and-span gas to the Zero/Span inlet, and disconnect the intake tube from the Sample connection. Disconnect the sample pump and plug the Pump connection.
EC155 CO2 and H2O Closed-Path Gas Analyzer i. 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.
EC155 CO2 and H2O Closed-Path Gas Analyzer FIGURE 9-6. ECMon Zero/Span window l. Enter the known concentration of CO2 (in ppm) in the Span Concentration box and press Span. This will cause the analyzer to adjust the value of its CO2 Span parameter, forcing the measured CO2 concentration to the value specified. Verify the CO2 concentration reads the correct value. m. Replace the CO2 span gas with an H2O span gas of known dew point.
EC155 CO2 and H2O Closed-Path Gas Analyzer CAUTION b. Unscrew the large metal plug found at the base of the analyzer next to the analyzer cable; it should only be hand-tight (see FIGURE 9-7). Once the plug is removed, tip the analyzer up so the desiccant/scrubber bottle falls out. Insert a new bottle lid-first into the analyzer. Firmly screw the plug back in place. c. On the other end of the analyzer, remove the two seal-screws from the metal cap (see FIGURE 9-8). Carefully pull the cap off.
EC155 CO2 and H2O Closed-Path Gas Analyzer FIGURE 9-8. Replacing the detector housing desiccant/scrubber bottle 9.6 Factory Recalibration When the EC155 is manufactured, it goes through an extensive calibration process, covering a wide range of temperatures, pressures, and gas concentrations.
EC155 CO2 and H2O Closed-Path Gas Analyzer 10. Datalogger Programming with CRBasic CRBasic supports two instructions to communicate with the EC100 via SDM. The first is the EC100() instruction, which reads measurement data from the EC100. The second is the EC100Configure() instruction, which receives and sends configuration settings. 10.1 EC100() Instruction The EC100() instruction is used to retrieve data from the EC155 via SDM.
EC155 CO2 and H2O Closed-Path Gas Analyzer 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 µmol/mol 7 H2O mmol/mol 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.
EC155 CO2 and H2O Closed-Path Gas Analyzer TABLE 10-3.
EC155 CO2 and H2O Closed-Path Gas Analyzer 10.2 EC100Configure() Instruction This instruction is another way, besides ECMon and Device Configuration, to retrieve and modify settings. ECmon and Device Configuration are userinteractive, while the EC100Configure() instruction allows automated control under CRBasic datalogger programming. EC100Configure() is a processing instruction. Whether running in pipeline mode or sequential mode the datalogger will execute the instruction from processing.
EC155 CO2 and H2O Closed-Path Gas Analyzer 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.
EC155 CO2 and H2O Closed-Path Gas Analyzer 10.2.1 ConfigCmd 11 Zero-and-Span Control To perform zeroing of CO2 and H2O, ConfigCmd 11 is set to 1. After the EC155 completes the zero, it will write the value to -1. The datalogger can poll this value or simply wait for a period of time to allow the zeroing to complete. To perform CO2 span, the CO2 Span Concentration setting (ConfigCmd 12) must be written to the proper value in ppm CO2 prior to setting the Span/Zero Control setting (ConfigCmd 11) to 2.
EC155 CO2 and H2O Closed-Path Gas Analyzer 10.
EC155 CO2 and H2O Closed-Path Gas Analyzer 11. Theory of Operation The EC155 is a non-dispersive mid-infrared absorption analyzer. Infrared radiation is generated in the larger block of the analyzer before propagating through a 12 cm sample cell. Chemical species located within the sample cell will absorb radiation at characteristic frequencies.
Appendix A. Filter Bandwidth and Time Delay The EC100 measures CO2 and H2O from the EC155 gas analyzer head (as well as wind velocity and sonic temperature from the optional CSAT3A sonic head) 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 well-attenuated stop band.
Appendix A. Filter Bandwidth and Time Delay the non-EC100 data by two datalogger scans to match the EC100 data. For the best synchronicity, choose a datalogger scan interval that is an integer multiple of the EC100 filter delay. The EC100 measures the gas and wind data at 100 Hz, and the 100-Hz data are down-sampled to the datalogger’s scan rate through SDM communications (see Section 8, EC100 Outputs).
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-msec 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. Useful Equations The following table lists all the variables and constants used in the equations below: Variable or Constant Table of Variables and Constants 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. Useful Equations PM d Xv 1 − ρ d = R(T + 273.15) 1000 + X v (B-5) Dew Point from Molar Mixing Ratio Td = 240.97 Td _ tmp (B-6) 17.502 − Td _ tmp XvP Td _ tmp = ln 0.61121 ⋅ f (1000 + X v ) ( ) ( (B-7) ) f = 1.00072 + 3.2 × 10 −5 P + 5.9 × 10 −9 PT 2 (B-8) Water Vapor Molar Mixing Ratio from Dew Point Xv = e 1000 P−e (B-9) 17.502Td e = 0.61121⋅ f ⋅ EXP 240.97 + Td (B-10) Water Vapor Mass Density from Dew Point ρv = (0.
Appendix C. EC155 Sample Cell and Intake Maintenance The following steps can be undertaken when the sample cell and intake tube becomes dirty, or as part of routine maintenance of the EC155. Refer to Section 9.3, Cleaning Analyzer Windows, for figures and instructions for accessing and removing the analyzer from the sample cell. C.1 Cleaning Sample Cell NOTE 1. Turn off the pump. 2. Power down the analyzer. 3. Remove the analyzer from the sample cell. 4.
Appendix C. EC155 Sample Cell and Intake Maintenance NOTE 3. Plug the hole in the inlet with your finger. The pump will pull a vacuum on its internal filter/buffer volume, the pump tube, analyzer, and intake tube. 4. After approximately one minute, unplug the hole. During these steps, ambient air will rush in and blow dust from the inner walls of the intake tube, which is likely be deposited on the analyzer windows.
Appendix D. Material Safety Data Sheets (MSDS) D.
Appendix D. Material Safety Data Sheets (MSDS) D.
Appendix D.
Appendix D.
Appendix E.
Appendix E.
Campbell Scientific Companies Campbell Scientific, Inc. (CSI) 815 West 1800 North Logan, Utah 84321 UNITED STATES www.campbellsci.com • info@campbellsci.com Campbell Scientific Centro Caribe S.A. (CSCC) 300 N Cementerio, Edificio Breller Santo Domingo, Heredia 40305 COSTA RICA www.campbellsci.cc • info@campbellsci.cc Campbell Scientific Africa Pty. Ltd. (CSAf) PO Box 2450 Somerset West 7129 SOUTH AFRICA www.csafrica.co.za • cleroux@csafrica.co.za Campbell Scientific Ltd.
