R. M. Young, 43502, Compact Aspirated Radiation Shield, 115V / 60 HzThe Aspirated Radiation Shield provides maximum sensor protection from incoming short wave and outgoing long wave radiationThe shield employs a triple walled intake tube and multiple canopy shades to effectively isolate the sensor from precipitation and solar radiation. A continuous duty DC blower provides constant flow of ambient air over the sensor.Model 43502 Aspirated Radiation Shield provides accurate ambient air temperature measurements in a unique low cost, small size, and conservatively rated instrument. Radiation errors are less than 0.2° C RMS with the shield exposed to solar radiation of 1000 W/m2. The triple wall shield employs three concentric downward facing intake tubes and a canopy shade to isolate the temperature sensor from direct and indirect radiation. The temperature sensor mounts vertically in the center of the intake tubes.The small shield size reduces the surface area exposed to incoming radiation during the day, significantly reducing the amount of heat that needs to be washed away from the intake tubes. Errors from outgoing radiation at night are similarly reduced. A continuous duty brushless DC blower pulls ambient air into the shield and across the temperature sensor. Flow rate at the sensor is 5 to 11 m/s, depending upon sensor size. Brush-less electronic commutation of the blower motor is achieved using dependable solid-state circuitry. The blower is designed for continuous duty of more than 80,000 hours (9 years) at 25° C (77° F).The blower housing and shield assembly are made from white UV stable plastic, which provides high reflectivity, low heat conduction, and maximum weatherability. The mounting bracket with a plastic v-block and stainless steel U-bolt will accommodate a vertical mounting post of 25 to 50 mm (1 to 2 in) diameter and allows easy height adjustment.The Model 43502 is ideally suited for lapse rate measurements. With identical shields and sensors at 2 m and 10 m levels, the temperature difference (delta T) can be measured with a relative accuracy of 0.05° C RMS under conditions of maximum solar radiation.