Campbell UT30 Installation Manual

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Campbell UT30 Installation Manual Manual pdf 43 page image

SECTION 4. SENSOR INSTALLATION4-104.19 ENCLOSURE HUMIDITY SENSORInstall the PN 10162, HM2000 Humidity Sensorin the enclosure to monitor enclosure humidity.The MetData1 and ET101/106 are shipped withthis sensor pre-installed.FIGURE 4.19-1. Enclosure Humidity Sensor4.20 WIND DIRECTION SENSORORIENTATION4.20.1 DETERMINING TRUE NORTH ANDSENSOR ORIENTATIONOrientation of the wind direction sensor is doneafter the datalogger has been programmed, and thelocation of True North has been determined. TrueNorth is usually found by reading a magneticcompass and applying the correction for magneticdeclination*; where magnetic declination is thenumber of degrees between True North andMagnetic North. Magnetic declination for a specificsite can be obtained from a USFA map, localairport, or through a computer service offered bythe USFS called GEOMAG (Section 4.20.2). Ageneral map showing magnetic declination for thecontiguous United States is shown in Figure 4.20-1.Declination angles east of True North areconsidered negative, and are subtracted from 0degrees to get True North as shown Figure 4.20-2.Declination angles west of True North are con-sidered positive, and are added to 0 degrees to getTrue North as shown in Figure 4.20-3. Forexample, the declination for Logan, Utah is 16°East. True North is 360° - 16°, or 344° as read ona compass.Orientation is most easily done with two people,one to aim and adjust the sensor, while theother observes the wind direction displayed bythe datalogger.1. Establish a reference point on the horizon forTrue North.2. Sighting down the instrument center line, aimthe nose cone, or counterweight at True North.Display the input location for wind directionusing the *6 Mode of the datalogger, or, theMonitor Mode of GraphTerm with an on-linePC.3. Loosen the band clamps or set screws thatsecure the base of the sensor to the mast orcrossarm. While holding the vane position,slowly rotate the sensor base until thedatalogger indicates 0 degrees. Tighten theband clamps or set screws loosenedpreviously.4. Engage the orientation ring indexing pin inthe notch at the instrument base (05103and 05305 sensors only), and tighten theband clamp on the orientation ring.* Other methods employ observations usingthe North Star or the sun, and arediscussed in the Quality AssuranceHandbook for Air Pollution MeasurementSystems, Volume IV - MeteorologicalMeasurements 4.