.Magee Scientific The Aethalometer ™ 2005.07 A.D.A. Hansen Magee Scientific Company Berkeley, California, USA Copyright © 2005 Magee Scientific Company, Berkeley, CA The Aethalometer ™ - 19-inch rack mount chassis version Magee Scientific i www.mageesci.com The Aethalometer ™ - ‘Portable’ chassis version Magee Scientific ii www.mageesci.com TABLE OF CONTENTS 1. INTRODUCTION ............................................................................................................ 8 2. “QUICK-START” SUMMARY...................................................................................... 9 2.1 WHAT DOES IT MEASURE? ................................................................................................................. 9 2.2 HOW DOES IT WORK?....................................................................................................................... 10 2.3 USEFUL USER FEATURES................................................................................................................. 11 2.4 GUIDELINES FOR SETTING UP AN AETHALOMETER.......................................................................... 12 2.5 FIELD REFERENCE SUMMARY ......................................................................................................... 14 Scientific Background 3. AEROSOL BLACK CARBON ..................................................................................... 15 3.1 ORIGINS........................................................................................................................................... 15 3.2 EFFECTS .......................................................................................................................................... 17 3.3 DEFINITIONS AND ANALYTICAL TECHNIQUES.................................................................................. 19 4. THE OPTICAL ATTENUATION METHOD............................................................. 22 4.1 INTERCOMPARISON OF THE METHOD WITH OTHER ANALYTICAL TECHNIQUES.................................. 24 4.1.1 Comparison with Optical Methods ........................................................................... 24 4.1.2 Comparison with Chemical Methods ........................................................................ 28 4.2 INTERPRETATION OF OPTICAL ATTENUATION IN THE ULTRA-VIOLET: DEFINITION OF ‘UVPM’ ..... 32 4.3 INTERPRETATION OF OPTICAL ATTENUATION ‘SPECTRUM’: MULTI-WAVELENGTH INSTRUMENT ... 36 4.3.1 'Standard Wavelength Set’ Optical Source ............................................................... 36 4.3.2 'Alternative Wavelength Set’ Optical Source ............................................................ 38 4.4 ABSORPTION CROSS-SECTION CALIBRATION OPTIONS..................................................................... 39 4.5 EXAMPLES OF MULTIPLE WAVELENGTH AETHALOMETER DATA .................................................... 40 4.6 THE AETHALOMETER PRINCIPLE ..................................................................................................... 44 4.7 AEROSOL SAMPLING........................................................................................................................ 45 4.8 MEASUREMENT OF OPTICAL ATTENUATION .................................................................................... 46 4.9 THE AETHALOMETER ALGORITHM .................................................................................................. 48 Instrument Details 5. THE AETHALOMETER™ .......................................................................................... 50 5.1 OPTICAL HEAD AND PHOTODETECTORS .......................................................................................... 51 5.2 SAMPLE COLLECTING SPOT: “EXTENDED RANGE” VS. “HIGH SENSITIVITY” INLETS....................... 52 5.3 AUTOMATIC TAPE FEEDER .............................................................................................................. 53 5.4 PANEL CONTROLS AND DISPLAYS ................................................................................................... 54 5.5 AIR MASS FLOW METER.................................................................................................................. 55 5.6 COMPUTER OPERATION................................................................................................................... 56 5.7 POWER REQUIREMENTS................................................................................................................... 57 5.7.1 A.C. Line Power Operation....................................................................................... 57 5.7.2 Low-Power 12-Volt Operation.................................................................................. 57 5.8 INSTALLATION REQUIREMENTS ....................................................................................................... 58 5.9 FILTER TAPE.................................................................................................................................... 59 Magee Scientific iii www.mageesci.com 5.10 FILTER SPOT ADVANCING................................................................................................................ 60 5.10.1 ‘Maximum Attenuation Value’ .................................................................................. 60 5.10.2 Data Loss during Tape Advance............................................................................... 61 5.11 “TAPE SAVER”: FLOW BYPASSING .................................................................................................. 62 5.12 PRECISION AND REPRODUCIBILITY .................................................................................................. 64 6. THE “PORTABLE” MODEL AE-42 AETHALOMETER ....................................... 65 7. AEROSOL INLET REQUIREMENTS ....................................................................... 69 7.1 INSECTS AND RAIN .......................................................................................................................... 70 7.1.1 Recommended Inlet Construction ............................................................................. 71 7.2 SAMPLE INLET TUBING CONNECTORS ............................................................................................. 72 8. PUMPING ....................................................................................................................... 73 8.1 GENERAL PRINCIPLES OF SAMPLE COLLECTION .............................................................................. 73 8.2 PUMP OPTIONS ................................................................................................................................74 8.2.1 Internal diaphragm pump – Variable-Speed DC Motor ........................................... 74 8.2.2 External Pump........................................................................................................... 74 9. SENSITIVITY AND NOISE ......................................................................................... 75 9.1 GENERAL PRINCIPLES...................................................................................................................... 75 9.2 STABILITY EXAMPLE – AE16 .......................................................................................................... 77 10. INTERPRETATION OF DATA ................................................................................... 79 10.1 GENERAL PRINCIPLES...................................................................................................................... 79 10.2 INTERPRETATION OF UV DATA WITH VOLATILE ORGANIC SPECIES................................................. 83 10.3 DATA DISPLAY TEMPLATES............................................................................................................. 84 10.4 THE ‘WASHINGTON UNIVERSITY’ DATA PROCESSOR ...................................................................... 84 Technical Operation 11. UNPACKING AND SETTING UP THE INSTRUMENT.......................................... 85 11.1 SHIPMENT CONTENTS...................................................................................................................... 85 11.2 HARDWARE SET-UP ........................................................................................................................ 87 11.2 HARDWARE SET-UP ........................................................................................................................ 87 11.3 SOFTWARE SET-UP.......................................................................................................................... 88 11.4 “QUICK SET-UP SUMMARY GUIDE” ................................................................................................ 89 12. FILTER TAPE INSTALLATION ................................................................................ 91 12.1 GENERAL INFORMATION.................................................................................................................. 91 12.2 INSTALL NEW TAPE – OPERATOR ACTIONS – RACK-MOUNT MODELS ............................................ 92 12.3 INSTALL NEW TAPE – SOFTWARE PROCEDURE PROMPTS................................................................ 94 13. OVERVIEW OF AUTOMATIC OPERATION.......................................................... 95 14. SOFTWARE.................................................................................................................... 97 14.1 GENERAL PRINCIPLES.....................................................................................................................