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Tipping Bucket Rain Gauge Models 6011-A 6011-B · PDF fileTipping Bucket Rain Gauge Models 6011-A 6011-B 1165 National Drive • Sacramento, CA 95834 • 800.824.5873 User’s Manual

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  • Tipping BucketRain GaugeModels 6011-A

    6011-B

    1165 National Drive Sacramento, CA 95834 800.824.5873

    UsersManual

  • iii

    Table of ContentsGeneral Information ........................................................................................... 1

    Introduction .............................................................................................................. 1

    InstallationGeneral ...................................................................................................................... 2Siting ......................................................................................................................... 2Standard Installation ................................................................................................. 2AWOS Installation .................................................................................................... 2 AWOS Pad Installation ........................................................................................... 2 AWOS Tower Installation ....................................................................................... 2Connection ................................................................................................................ 3

    Theory of Operation ............................................................................................ 4Operation ................................................................................................................... 4

    Calibration .......................................................................................................... 5Calibration Requirements .......................................................................................... 5Calibration ................................................................................................................. 5Adjustment ................................................................................................................ 5Field Checks .............................................................................................................. 6

    Maintenance ...................................................................................................... 8General ...................................................................................................................... 8AWOS Periodic Maintenance ................................................................................... 8 Tools and Equipment Required ............................................................................... 8 Monthly Maintenance ............................................................................................. 8 Quarterly Maintenance ............................................................................................ 8 Annual Maintenance ............................................................................................... 8

    Warranty .............................................................................................................. 9

    Specifications .................................................................................................... 10

    Drawings ............................................................................................................ 11

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    1 General Information1.1Introduction

    The Tipping Bucket Rain Gaugeis a precision sensor used to mea-

    sure rainfall volume and/or rate. Rainenters the gauge through a machinedorifice and fills one of two buckets lo-cated inside the gauge. Each tip of thebucket represents 0.01 inches (0.25 mm)of rainfall with the Model 6011-A, whileModel 6011-B accommodates 0.1 mm

    of rainfall per tip. As the bucket tips, areed switch makes a momentary closure,registering the tip.

    Corrosion-resistant materials are used inconstruction of this instrument, and allexternal openings are protected frominsects and foreign material by meshscreens.

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    2 Installation2.1General

    This instrument is thoroughly tested and fully calibrated at the factory and is ready forinstallation.

    2.2Siting

    2.3Standard Installation

    2.4.1AWOS PadInstallation

    Two prime considerations must be evalu-ated when locating an installation site forthis rain gauge. The gauge must bemounted level and the gauge must beadequately protected from high winds.Errors of more than 5% can occur if notprotected from the wind, due to rainfallblowing over the lip of the orifice.

    Consider the height of surrounding ob-stacles. Install the rain gauge at a dis-tance away from the obstacles two tofour times the obstacles height. Al-though the obstacle makes an ideal windshield, it may block the normal rainfallpath into the gauge or rainfall may blowoff the obstacle and into the gauge.

    The rain gauge is normally mounted to apoured concrete pad with embeddedmounting bolts. To mount the rain gaugeto a pad:

    Pour a 2 ft. x 2 ft. level concretefoundation about 4 inches deep.

    Embed three 1/4" or 3/8" diameterbolts so that they protrude outwardfrom the foundation, spaced to fitthe three feet on the gauge.

    If strong winds are common at the site,the model 6410 Wind Screen isrecommended. Mount the wind screenas described in its accompanying manual.

    Remove the collection funnel and checkthe bubble level on the base assemblybefore bolting the gauge to the foundationor tower mount. If the bubble is notcentered, add washers between the baseand the base assemblys feet in such away that the bubble is centered exactlywhen the bolts are tightened. This is ofcritical importance to the accuracyof the gauge.

    Connect the input of the recording de-vice to the two binding posts that termi-nate the reed switch.

    Replace the collection funnel and securethe two side screws.

    To mount the sensor to a pad, constructthe pad using a Ready-Form tube, rebar,and foundation bolts as shown in Figure2-1, then proceed as follows:

    Remove the collection funnel and checkthe bubble level on the base assemblybefore bolting the gauge to the foundationor tower mount. If the bubble is notcentered, add washers between the baseand the base assemblys feet in such a

    way that the bubble is centered exactlywhen the bolts are tightened. This is ofcritical importance to the accuracyof the gauge.

    Connect the input of the recording de-vice to the two binding posts that termi-nate the reed switch.

    Replace the collection funnel and securethe two side screws.

    2.4AWOS Installation

    Rain gauges used at AWOS installations can be mounted to a pad or to the sensortower.

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    MODEL 6011 TIPPING BUCKET RAIN GAUGE

    2.5Connection

    Connect a two-conductor cable betweenthe two terminal posts on the gauge andthe event accumulating device.

    Be sure to remove any packing materialand the bucket retaining clips from theinstrument.

    Verify correct calibration before rein-stalling the outer housing.

    (Figure 2-1) AWOS rain gauge pad construction.

    2.4.2AWOS TowerInstallation

    Using the M488169-01 tower mountingkit, the sensor mounts to a horizontalboom attached to the tower approximately7' above the ground. To mount the raingauge to a tower, refer to Drawing No.M488169-01-007 at the back of thismanual, then proceed as follows:

    Remove the collection funnel and checkthe bubble level on the base assemblybefore bolting the gauge to the foundationor tower mount. If the bubble is not

    centered, add washers between the baseand the base assemblys feet in such away that the bubble is centered exactlywhen the bolts are tightened. This is ofcritical importance to the accuracyof the gauge.

    Connect the input of the recording de-vice to the two binding posts that termi-nate the reed switch.

    Replace the collection funnel and securethe two side screws.

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    3 Theory of OperationThe rain gauges eight inch diameterorifice was chosen as a compromisebetween two conflicting elements theincreased accuracy of a large samplingarea, and the practical benefits of a smalltipping bucket mechanism.

    Precipitation is collected by the largefunnel at the gauge orifice, which helpsprevent evaporation inside the instru-ment. The collected precipitation is thenchanneled to the small funnel inside theinstrument and directed to one of twotipping buckets. When one bucket fills,its weight tips the next bucket into positionand the first empties. At the same time,a 100 millisecond momentary contactclosure increments an event accumulat-ing device. The measured water is

    drained out the bottom of the instrument.A tank can be designed, if needed, tocatch the water draining out of the in-strument for further evaluation.

    In AWOS systems, the rain gauge isused to correct visibility measurementswhen precipitation is present. Whenprecipitation is falling, visibilitymeasurements register a value less thanthe actual visibility. The degree to whichthe visibility value is affected dependson the intensity of the precipitation. Tocorrect for this, the AWOS interpretsthe rain gauge data and corrects thevisibility value with one of severalcorrection factors corresponding to theintensity of the precipitation.

    3.1Operation

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    4 Calibration4.1CalibrationRequirements

    This instrument was calibrated beforeleaving the factory and should not re-quire any further calibration unless main-tenance is performed on the instrument.

    For Model 6011-A, 8.683 milliliters ofwater is equivalent to 0.01" of rainfalland 8.493 milliliters of water is equiva-lent to 0.25 mm of rainfall. For Model6011-B, 3.418 milliliters of water equals0.1 mm of rainfall.

    4.2Calibration

    To calibrate the tipping bucket rain gauge,follow the steps below:

    Remove the two screws at the bas

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