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Campbell KH20 Instruction Manual

Krypton hygrometer
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KH20 Krypton Hygrometer
2/10
C o p y r i g h t
©
2 0 1 0
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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Summary of Contents for Campbell KH20

  • Page 1 KH20 Krypton Hygrometer 2/10 C o p y r i g h t © 2 0 1 0 C a m p b e l l S c i e n t i f i c , I n c .
  • Page 2 If the form is not received within three days of product receipt or is incomplete, the product will be returned to the customer at the customer’s expense. Campbell Scientific reserves the right to refuse service on products that were exposed to contaminants that may cause health or safety...

  • Page 3: Table Of Contents

    6. Maintenance and Calibration........9 6.1 Visual Inspection ..................9 6.2 Testing the Source Tube ................9 6.3 Testing the Detector Tube ................9 6.4 Managing the Scaling of KH20 ..............10 6.5 Older KH20 ....................10 6.6 Calibration ....................10 Appendix A. Calibrating KH20 ............. A-1 A.1 Basic Measurement Theory ..............
  • Page 4 KH20 Table of Contents Tables 1. Datalogger Connections for Differential Measurement ......5 2. KH20 Calibration Ranges ................6 A-1. Linear Regression Results for KH20 ln(mV) vs. Vapor Density ..A-2 A-2. Final Calibration Values for KH20............ A-3...

  • Page 5: General Description

    The KH20 is not suitable for absolute water vapor concentration measurements due to its signal offset drift. The KH20 heads are sealed and will not suffer damage should they get wet. In addition, the electronics box and the connectors are housed inside a rain shield (CSI p/n 14113) that protects them from moisture.

  • Page 6: Parts And Tools Needed For Mounting

    Allen Wrench (5/32”) (CSI p/n 4697) 3. Installation 3.1 Siting When installing the KH20 sensor for latent heat flux measurement in an eddy covariance application, proper siting, sensor height, sensor orientation and fetch are important. Please refer to Section 2 Installation and Mounting of the Open Path Eddy Covariance System manual for more discussion on siting.

  • Page 7: Mounting The Kh20 Sensor

    3. Mount the 12 inch long pipe (CSI p/n 18048) to a crossarm via 1” x 3/4” Nu-rail (CSI p/n 1049). 4. Mount the KH20 onto the 12” long pipe using a 3/4” x 3/4” Nu-rail (CSI p/n 1017). Mount the KH20 such that the source tube, the longer of the two tubes, is positioned on top, as shown in Figure 1.
  • Page 8 3. Mount the rain shield onto the tripod or tower mast using the U-bolt provided. Make sure that the distance between the KH20 sensor head and the rain shield is within 5 feet so that the cables from the sensor head will be within reach of the electronics box.

  • Page 9: Wiring

    6. Gather any loose cables and tie them up, using cable ties, onto the tripod or tower mast. 4. Wiring The KH20 sensor is shipped with a power/signal cable with a 25 ft standard lead length. Table 1 shows the connections for the KH20 to the CR1000, CR3000, and CR5000.

  • Page 10: Datalogger Programming

    The water vapor absorption coefficient for three different vapor ranges are calculated from the collected calibration data: full range, dry range, and wet range. Table 2 shows a sample of the KH20 vapor ranges over which three different water vapor absorption coefficients are calculated.

  • Page 11: Example 1, Cr3000 Program To Measure Water Vapor Fluctuations

    'CR3000 Series Datalogger 'This datalogger program measures KH20 Krypton Hygrometer. 'The station operator must enter the constant and the calibration value for the KH20. 'Search for the text string "unique" to find the locations of these constants 'and enter the appropriate values found from the calibration sheet of the KH20.
  • Page 12 KH20 Krypton Hygrometer '*** Variables *** Public panel_temp Public batt_volt Public kh(2) Public rho_w Alias kh(1) = kh_mV Alias kh (2) = ln_kh Units panel_temp = deg_C Units batt_volt = volts Units kh_mV = mV Units ln_kh = ln_mV Units rho_w = g/m^3...

  • Page 13: Maintenance And Calibration

    Section 6.3 below. 6.3 Testing the Detector Tube If the source tube tests fine but the output from KH20 is still in question, perform the following test. Prepare a piece of paper and insert it between the source tube and the detector tube to completely block the optical path. You...

  • Page 14: Managing The Scaling Of Kh20

    50 mV, when the paper is removed from the optical path, the source tube may be at fault. Obtain an RMA from Campbell Scientific, Inc. and send the unit in for repair. 6.4 Managing the Scaling of KH20...

  • Page 15: Basic Measurement Theory

    ρ. The KH20 sensor uses the UV light emitted by the krypton lamp: major line at 123.58 nm and the minor line at 116.49.
  • Page 16 ρ . Campbell Scientific, Inc. performs the calibration twice for each KH20: once with the window cleaned, and again with the window scaled. We then break up the vapor density range into dry...
  • Page 17 Appendix A. Calibrating KH20 the KH20 calibration certificate contains. The data shown in Table A-2 is from an actual KH20. TABLE A-2. Final Calibration Values for KH20 Vapor Range Slope Y Intercept Coefficient (g/m ln (V Full Range 1.74 ~ 19.25 -0.205...
  • Page 18 Appendix A. Calibrating KH20...
  • Page 20 Campbell Scientific Companies Campbell Scientific, Inc. (CSI) 815 West 1800 North Logan, Utah 84321 UNITED STATES www.campbellsci.com • info@campbellsci.com Campbell Scientific Africa Pty. Ltd. (CSAf) PO Box 2450 Somerset West 7129 SOUTH AFRICA www.csafrica.co.za • cleroux@csafrica.co.za Campbell Scientific Australia Pty. Ltd. (CSA)

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