Why the LI-7000? A Comparison Between LI-7000 and LI-6262 A Comparison Between LI-7000 and LI-6262 First introduced in 1990, the LI-6262 CO2/H2O Analyzer quickly became a favorite of researchers worldwide for a variety of applications (e.g. eddy covariance measurements) where high speed and precision were required. The LI-7000 CO2/H2O Analyzer was introduced in 2000 and expanded on the capabilities of the LI-6262 based on feedback we received from you, our customers. The LI-6262 is now discontinued. This document is intended to show why we believe the LI-7000 remains a superior solution for all of your CO2/H2O measurement needs, and in particular, for those users familiar with or currently using the LI-6262. LI-7000 DIFFERENTIAL/ABSOLUTE MODE OPERATION Reference cell concentration can be estimated. LI-6262 Accuracy depends on reference cell concentration being known. ________________________________________________________________________________________________________ OPTICAL BENCH One optical bench. Sample cell size: 9.53 mm D x 152.4 mm L (0.375" x 6"). Volume: 10.86 cm3 One optical bench. Sample cell size: 6 mm H x 13 mm D x 152 mm L (0.25" x 0.5" x 6"). Volume: 11.9 cm3 ________________________________________________________________________________________________________ OPTICAL CELL CLEANING Optical cells can be cleaned in the field without affecting instrument calibration. Optical cells can be cleaned only at the factory, and the instrument requires recalibration. ________________________________________________________________________________________________________ AUXILIARY PUMP Software controlled internal air pump is standard. The chopper housing is scrubbed by internal chemicals and does not need a pump for scrubbing. The pump can be used for other purposes such as scrubbing the reference cell during absolute mode operation. Optional auxiliary pump attaches to the back of the instrument, required for scrubbing water vapor from the chopper housing when making water vapor measurements, and used for scrubbing the reference cell during absolute mode operation. ________________________________________________________________________________________________________ HEAT EXCHANGERS Heat exchangers equilibrate incoming air to cell temperature. Not Available ________________________________________________________________________________________________________ PRESSURE SENSOR Standard 0.1% accuracy pressure sensor Optional 0.1% accuracy pressure sensor ________________________________________________________________________________________________________ MAXIMUM FLOW RATE Internal diameter of the standard IRGA inlet and outlet ports is 4.7 mm. A flow rate of 10 liters/min produces a cell pressure of about 0.01 kPa. Internal diameter of the standard IRGA inlet and outlet ports is 2.5 mm. A flow rate of 10 liters/min produces a cell pressure of about 0.2 kPa. ________________________________________________________________________________________________________ From total vacuum to 115 kPa (17 psi) Max allowable pressure is 115 kPa (17 psi) with pressure sensor connected and 200 kPa (29 psi) without pressure sensor connected. ________________________________________________________________________________________________________ GAS PRESSURE IN OPTICAL CELL INTERNAL HUMIDITY SENSOR Detector housing humidity sensor warns when to replace internal chemicals. Not Available ________________________________________________________________________________________________________ OPERATING TEMP. RANGE 0–55 °C optical bench 0–50 °C optical bench ________________________________________________________________________________________________________ MICROPROCESSOR 400 MHz 9 MHz ________________________________________________________________________________________________________ LI-7000 SUPPORT SOFTWARE LI-6262 Windows® based software for setup, control and data logging DOS based software for command line interrogation and data collection 4 user-scalable DACs, 600 Hz update frequency (±5v maximum, 14-bit D/A conversion) 2 user-scalable DACs, update rates of 5 Hz for CO2 and 3 Hz for H2O (0-100 mV, 0-5V, or 0-20mA full scale, 12-bit D/A conversion). Raw, non-linearized output for CO2 and H2O at 5 Hz bandwidth. BACK PANEL CONNECTIONS Analog Output Channels 1 dedicated presure output (0-115 kPa = 0-3V) Auxiliary Input Channels Two, -2.5 to +2.5V. One, 0 to +4.096V. RS-232 9600 to 115,200 baud, 8, N, 1. Supports XON/XOFF Baud rates up to 9600, 8, N, 1. Supports XON/XOFF USB Data output rate up to 50 Hz. USB 2.0 compliant. None DATA CHECKSUM USB or RS-232 Yes. Used to ensure integrity of transmitted data. No DISPLAY 8 line by 40 character backlit LCD with enlarged characters. Real-time graphing activated by a single keystroke. 2 line by 16 character backlit LCD with enlarged characters. POWER REQUIREMENTS 100–240 VAC, 50–60 Hz or 10.5–16 VDC, 1.5–4 amp max depending on temperature and pump usage 100–130 VAC or 200–260 VAC (47–65 Hz) or 10.5–16 VDC, 1.5 amp max DIMENSIONS 36.8 cm L x 12.7 cm H x 25 cm D (14.5" L x 5" H x 9.875" D) 33.5 cm L x 13 cm H x 24 cm D (13" L x 5" H x 9.5" D) WEIGHT 8.8 kg (19.4 lbs) 3.5 kg (7.7 lbs) WARM UP TIME 2 minutes to operation, 2 hours to temperature equilibration 5 minutes to operation, 1/2 hour to temperature equilibration CO2 OPERATING RANGE The factory calibration polynomial is valid in the range of 0–3,000 ppm; however, the instrument’s A/D does not over range even at 50,000 ppm, although sensitivity is reduced at high concentrations. A/D converter over ranges at about 10,000 ppm when detector output exceeds 7.5 volts. CO2 NOISE Typically 0.14 ppm peak-to-peak at 370 ppm with 1 second signal averaging Typically 0.3 ppm peak-to-peak, at 370 ppm with 1 second signal averaging CO2 ZERO DRIFT WITH TEMP. Typically 0.3 ppm/°C Typically 0.18 ppm/°C H2O NOISE 0.01 mmol/mol peak-to-peak at 10 mmol/mol, with 1 second signal averaging 0.015 mmol/mol peak-to-peak at 10 mmol/mol, with 1 second signal averaging H2O ZERO DRIFT WITH TEMP. Typically 0.02 mmol/°C Typically 0.008 mmol/°C continued on back LI-7000 and LI-6262 Similarities ANALYZER TYPE Differential, NDIR (non-dispersive infrared) gas analyzer DETECTOR TYPE Lead Selenide, solid state (no sensitivity to motion) CO2 detection wavelength: 4.26 microns H2O detection wavelength: 2.59 microns INFRARED SOURCE Single element source with blackbody radiation characteristic; life >20,000 hours CHOPPER MOTOR LIFE Chopper motor life is typically >20,000 hours. DIFFERENTIAL/ABSOLUTE MODE OPERATION Operates in absolute or differential mode. AMBIENT OPERATING TEMP. RANGE 0-50 °C ambient POWER INPUT Accepts either AC or DC input. CO2 CALIBRATION RANGE Factory calibrated from 0–3,000 ppm using 13 working standard gases which have been calibrated with WMO standards. CO2 ACCURACY Absolute accuracy largely depends on the accuracy of the span gas used to set the analyzer response. The factory calibrated polynomial fits the 13 calibration gases to which the typical accuracy is about 1% of reading. DIRECT SENSITIVITY OF CO2 READING TO WATER VAPOR Software algorithm corrects for band broadening effects. H2O CALIBRATION RANGE 0–60 mmol/mol (dry air to 40 °C dew point) H2O ACCURACY Absolute accuracy largely depends on the accuracy of the H2O span gas used to set the analyzer response. The H2O calibration accuracy is typically about 1% of reading. DIRECT SENSITIVITY OF H2O READING TO CO2 None Specifications are subject to change without notice. 4421 Superior Street • P.O. Box 4425 • Lincoln, Nebraska 68504 USA North America: 800-447-3576 • International: 402-467-3576 • FAX: 402-467-2819 In Germany - LI-COR GmbH: +49 (0) 6172 17 17 771 [email protected] • [email protected] • www.licor.com LI-COR is an ISO 9001 registered company. © 2005 LI-COR, inc. LI-COR Gas Analyzers are covered by U.S. Patents and foreign equivalents, and patents pending. LI-COR is a trademark of LI-COR, Inc. PN980-06623 Rev. 1 10/05