Efficient measurement of evaporation

The class A evaporation pan is a device that is used to carry out a standardized measurement procedure to accurately measure the potential evaporation rate over a defined water surface. The evaporation rate is determined by daily measurements of the water level in the pan. This provides you with an evaporation data set that is essential as a reference for validating theoretical calculations or for comparison with other measurement methods.

By using this standard method worldwide, the observed evaporation can be reliably compared within and between different climatic regions. This in turn helps you to optimize your own evaporation models.

Design and function

The class A evaporation pan consists of a cylindrical, stainless steel pan with an inner diameter of 120.7 cm and a height of 25.4 cm. The material prevents corrosion and ensures a long service life. The tray is placed horizontally about 15 cm above the soil on a wooden pallet supplied. It is important that the air can circulate under the pan and that the location of the pan is not obscured by shadows from nearby structures. The use of wood provides better insulation from the soil and increases measurement accuracy.

Manual or automatic measurement data acquisition

The water level changes can be measured very accurately manually using a suspension measuring rod with an attached micrometer scale (0 ... 100 mm). This rests on a stilling well, which has leveling screws and a bubble level for precise alignment.

Alternatively, the water level can be determined automatically using a pressure sensor and recorded by a data logger.

Calibration and maintenance

Regular calibration and maintenance of the evaporation pan is essential for accurate and reliable measurements. This includes cleaning the pan, checking for corrosion or damage and calibrating the measuring device. For easy cleaning, the pan is equipped with a drainage outlet on the bottom.

Optional accessories

• Bird/fauna protection: Evaporation can only be accurately determined if there is no precipitation or if there are losses of water level independent of evaporation (e.g. due to drinking animals). To avoid other water losses, the evaporation pan can be optionally equipped with bird/fauna protection.
• Weather station: An additional weather station records the local precipitation. The recorded quantity is then included in the evaporation calculation.
• Automatic filling system on request: The evaporation tray can also be equipped with an automatic filling system. Contact us for a quote.