255-200 Class A Evaporation Pan 
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| 255-200 Class A Evaporation Pan shown with 255-210 Stillwell with Fixed Point and 255-211 Replacement Graduate |
The 255-200 Evaporation Pan is a standard National Weather Service Class A type for measurement of water evaporation. It is normally installed on a wooden platform set on the ground in a grassy location. The pan is filled with water and exposed to represent an open body of water. The pan is filled to within 2.5 inches of the top of the pan. The evaporation rate can be measured by manual readings or with an analog output evaporation gauge.
Construction Diagram for Evaporation Pan Platform (PDF)
Specifications
Material: Low carbon stainless steel, type 304, 18 gauge
Construction: Heliarc welded, 1/2" drain plug, NPT female coupling
Size: Cylindrical, inside dimensions 10" deep x 47-1/2" dia (254 mm x 1026 mm), wall thickness 0.047"
Volume: Approx 77 gallons (adding 7.7 gallons will raise water level in pan by 1")
Weight/shipping: 48 lbs/59 lbs (22 kg/27 kg)
Shipping box: 49" x 49" x 11" (oversize-cannot ship via UPS)
Manuals
Ordering Information
255-200 Class A Evaporation Pan
Historic Photos from the NOAA Photo Library
Evaporation station and check pan at private laboratory of Robert Horton. In: "Monthly Weather Review," 1919 September, p. 608.
"Gaging the Thirst of the Air" The observer is measuring the depth of water in the evaporation pan with a graduated glass tube (burette.) In: "The Realm of the Air" by Charles F. Talman, 1931. Library Call Number M/0030 T151r.
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Evaporation Sensors
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