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United States Department of Agriculture

Agricultural Research Service

Title: Time and Level Controlled Filling System for Class "a" Evaporation Pans

Authors
item Hanson, Clayton
item Burgess, Michael

Submitted to: Journal Hydrologic Engineering
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 30, 1996
Publication Date: N/A

Interpretive Summary: The National Water Service Class A evaporation pan is the standard measurem f evaporation in the United States. It is also used for establishing evapo piration demand. These pans generally have to be read and refilled manuall t recently developed integrated circuit technology and new reliable pressur nsducers have made it possible to develop a battery-operated system to auto oally fill class A evaporation pans from stored water. The system records ores pan level records every 15 minutes for later transmission to a central storage facility. The measurement sensitivity of the system is 0.02 cm of oration over a range of 3.5 cm. A field calibration of the system showed t here was a very good (R2=0.999) linear relationship between standard hook g nd pressure transducer water level measurements. This system is being used emote locations because the circuitry draws little current and small solar keeps the system's battery fully charged.

Technical Abstract: Recently developed integrated circuit technology and new reliable pressure ducers have made it possible to develop a battery-operated system to automa ly fill class A evaporation pans from stored water. The system records and es the average of 12 pan level records during a one min time period at the f every 15 minute period for later transmission to a central data storage f fty. The measurement sensitivity of the system is 0.02 cm of evaporation o range of 3.5 cm. A field calibration of the system showed that there was a good (R2=0.999) linear relationship between standard hook gage and pressur nsducer water level measurements. This system is being used in remote loca because the circuitry draws very little quiescent current. A small solar keeps they system's 12 V battery fully charged.

Last Modified: 10/25/2014
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