125 years of Calibration of Hydrometrical Current-Meters in Austria

For 125 years, hydrometrical current-meters and other flow velocity measuring devices are calibrated in Vienna.

The first calibration facility in Vienna's Prater had to be shut down after damage during the Second World War. From 1946, calibration activities were continued in Severingasse 7, in the present Institute for Hydraulic Engineering and Calibration of Hydrometrical Current-Meters, using a provisional technique. Since 1951, again had an own facility exists at our institute, which, in addition to calibration activities, is also used for other questions of water management research.

The task of the service is the calibration of flow velocity measuring devices. In this process, the devices are mounted on a measuring trolley and pulled through a long water tank at a precisely determined speed. The result of the calibration is the calibration equation. It represents the relationship between the reading of the tested meter and the speed of the measuring carriage. This speed is traceable to the international SI units. Thus, in addition to the accuracy of the measured values, calibration also ensures their international comparability.

Hydrometrical current-meters are used primarily by hydrographic services to survey flow. They are the basis for determining design floods and pollutant loads, but are also used to survey residual flows or assess the passability of fish ladders.

From 2023, the Institute of Hydraulic Engineering, which includes hydrometric testing, plans to move in the new hydraulic engineering laboratory at the University of Natural Resources and Applied Life Sciences and to abandon its current location. Due to the lack of its own calibration facility at the new location, calibration can no longer be carried out analogously to today from this point on. In coordination with the ministry and the hydrographic services of the federal states, work is currently being done on a new orientation of hydrometric testing adapted to the current needs and issues of hydrometry.

A black and white picture probably from the time before 1918.
On the far left the entrance to the garage, in the middle the actual main entrance to the (today's) institute. On the right, the gate to the testing facility for motor vehicles.

Construction of the calibration tank at Severingasse 7: The building site for the tank is located in the right part of the picture.

Hydrometrical current-meters can also be provided with large weights so that they lie stable in the flow when measuring on a rope even with high water flow.

Over the decades, the measurement technology for recording the wing pulses and the speeds of the carriage has been adapted to the state of the art several times and automated.

Measuring trolley in the calibration facility.

A hydrometrical current-meter during calibration.