Automating a class a evaporation pan for semi-continuous recording

✍ Scribed by G. Asrar; R.J. Kunze; D.E. Linvill

• Publisher: Elsevier Science
• Year: 1981
• Weight: 329 KB
• Volume: 25
• Category: Article
• ISSN: 0002-1571
• DOI: 10.1016/0002-1571(81)90080-7

✦ Synopsis

Continuous monitoring of water loss from an evaporation pan was automated by using a system of 16 general-purpose Constantan wire-resistance strain gages mounted on four supporting arms. A change in pan weight from water loss proportionally changed the electrical resistance of the wire gages. The system was assembled with a Class A evaporation pan and tested under field conditions as part of a larger evapotranspiration study. A dual-channel carrier--amplifier recorder in line with a digital data acquisition system was used to record the output of the system once every 2 rain. The system asssembly had a sensitivity of 0.034 mm of water for 0.1 mV change in bridge output. Total evaporation measured with this system was within 5% of manual measurements.