Campbell OBS-3A Spécifications

OBS-3A Turbidity and Temperature Monitoring SystemRevision: 11/11Copyright © 2007-2011Campbell Scientific, Inc.

Section 2. Instrument Setup Surveys The OBS-3A will usually be towed from a cable harness for surveys. The serial cable supplied with the unit is st

Section 2. Instrument Setup For extended deployment time, lithium batteries are a good alternative to alkaline batteries. Campbell Scientific sells

Section 2. Instrument Setup 2-4

Section 3. Operations 3.1 Software Installation Insert the CD and select “Install OBS-3A Utility”. Follow the installation wizard to install the so

Section 3. Operations Data received from OBS-3A while it is connected to the PC will be stored in this file (see FIGURE 3.2-3). FIGURE 3.2-3. Dat

Section 3. Operations 4. Click Connect/Disconnect to get a green light and synchronize the OBS-3A clock with your PC by clicking . 3.3 Pull-Down M

Section 3. Operations box to select ONLY change host computer port. Then click Apply and the button. If you get the OBS-3A information box, the bau

Section 3. Operations FIGURE 3.5-1. Test Data Sample FIGURE 3.5-2. Window for Viewing Instrument Information 3-5

Section 3. Operations 3.6 Water-Density and Barometric Corrections Since depths are estimated from pressure measurements, it is important to set the

Section 3. Operations length or the 2048 / rate. Note: the product of the rate and the duration cannot exceed 2048. Rate: Rate is the frequency of

WARRANTY AND ASSISTANCE This equipment is warranted by CAMPBELL SCIENTIFIC (CANADA) CORP. (“CSC”) to be free from defects in materials and wor

Section 3. Operations interval that will show the changes in turbidity and water depth that you wish to investigate. Rate sets the number measuremen

Section 3. Operations 3.11 Surveying If you have a pressure sensor, click the OBS menu and select Barometric Correction (do not do this when the OBS-

Section 3. Operations 4. A file for logging data was created when you started the OBS-3A Utility. You can review data at any time with Open and imp

Section 3. Operations 3.13 Scheduled Sampling Use this mode when you want the OBS-3A to sample at specific times, scheduled by hours and minutes, on

Section 3. Operations 4. Select setpoint values for transitions to fast sampling (SLOW>>>FAST) and slow (FAST>>>SLOW) rates. 5.

Section 3. Operations 7. Wait for the progress bar to disappear and examine data as a plot or test file (Section 3.17—Graphing and Printing). 3.16 S

Section 3. Operations 3.18 Excel Spreadsheets To make an Excel spreadsheet from OBS-3A data, start Excel and set file type to All. Open a data file a

Section 3. Operations 3.19 Erasing Data Memory To erase the flash data memory, do the following: 1) Click on the Terminal Mode Icon. 2) At the OB

Section 3. Operations 3-16

Section 4. Troubleshooting This section will help you isolate problems that can be easily fixed such as cable-continuity, processor reset, and batte

PLEASE READ FIRST About this manual Please note that this manual was originally produced by Campbell Scientific Inc. (CSI) primarily for the US market

Section 4. Troubleshooting 4. The OBS-3A and PC are not set to the same baud rate or communication protocol (e.g. RS-232, USB, RS-485). x Click an

Section 4. Troubleshooting Bright sun near the surface ( < 2 meters) or black-colored sediments cause erroneous OBS readings. Do not survey in sh

Section 4. Troubleshooting 4-4

Section 5. Maintenance 5.1 OBS Sensor The OBS sensor must be kept clean to measure sediment concentration or turbidity accurately. A gradual declin

Section 5. Maintenance during surveys or after each deployment. A sensor that has been stored dry should be soaked in water for 15 minutes prior to

Section 5. Maintenance carefully inspected every six months and serviced before all deployments longer than one month. 1. Disassemble O-ring seals a

Section 5. Maintenance 5-4

Section 6. Calibration 6.1 Turbidity This section briefly describes the materials and equipment you will need and the basic procedures for calibrati

Section 6. Calibration 6.1.2 Preparation 1. Experience has shown that only three calibration points are needed to get sub-1% accuracy. It is recomm

Section 6. Calibration There is no way to cancel a calibration after the Compute button is clicked. WARNING Review the quality assurance checks discu

Section 6. Calibration Where: Tstd = Turbidity of the standard solution; Tstk = Turbidity of the stock solution, usually 4000 NTU; Vstk = Cumulative

Section 6. Calibration x 2 gallons filtered distilled water (purified water from the super market works fine), x Hand-drill motor, x Paint stirrer

Section 6. Calibration Preparation 1. Clean containers and glassware with detergent and rinse with filtered water. 2. Perform the calibration under

Section 6. Calibration 9. Weigh 5 to l0 equal increments of the sediment so that the total dry weight will produce the maximum concentration expecte

Section 6. Calibration 6-8

Section 7. Optics and Turbidity Measurements Turbidity is the cloudy appearance of a liquid produced by light scattered from suspended matter. It i

Section 7. Optics and Turbidity Measurements 7-2 Can turbidity be converted to suspended solids concentrations and vise-versa? In most situations, co

Section 8. Factors Affecting OBS Response This section summarizes some of the important factors that affect OBS-3A measurements and shows how ignori

Section 8. Factors Affecting OBS Response 8.2 Suspensions with Mud and Sand As mentioned earlier, backscattering from particles is inversely related

Section 8. Factors Affecting OBS Response 0510Sediment Concentration (g/l)15012345Signal (V)A FIGURE 8.3-1. Response at High Sediment Concentrations

OBS-3A Table of Contents PDF viewers: These page numbers refer to the printed version of this document. Use the PDF reader bookmarks tab for links

Section 8. Factors Affecting OBS Response 02468Munsell Value (Black = 0)100.00.20.40.60.81.0Infrared ReflectanceCalciteBytowniteActinoliteMagnetite F

Section 8. Factors Affecting OBS Response in this region. OBS sensors are also more sensitive to mineral particles than either bubbles or particulat

Section 8. Factors Affecting OBS Response 8-6

Section 9. References See www.campbellsci.com/obs for a complete list of references. Conner, C.S. and A.M. De Visser. 1992. A Laboratory Investigati

Section 9. References 9-2 U.S. Geological Survey. 2003. National Field Manual of the Collection of Water-Quality Data. Book 9, Handbooks for Water-Re

Section 10. Specifications MEASUREMENT RANGE Turbidity (AMCO Clear)... 0.4 to 4,000 NTU1 Mud (D50=20μm) ...

Section 10. Specifications 10-2 CSI # 21135 End Cap Screws, 8-32 x 3/8”, socket (5/64”) CSI # 21120 Dummy Plug CSI # 21122 Plug Locking Sleeve, Subco

Campbell Scientific Companies Campbell Scientific, Inc. (CSI) 815 West 1800 North Logan, Utah 84321 UNITED STATES www.campbellsci.com • info@campbel

OBS-3A Table of Contents ii 6.1.3 OBS-3A Utility Software Steps... 6-2 6.1.4 Making Turbidity Standards

Section 1. Introduction The heart of the OBS-3A monitor is an OBS sensor for measuring turbidity and suspended solids concentrations by detecting n

Section 1. Introduction Depending on the number of sensors and the statistics selected, the OBS-3A can log as many as 200,000 lines of data (one per

Section 2. Instrument Setup 2.1 Mounting Suggestions Maximum depth for the OBS-3A housing is 300 meters. Working depths for individual instruments