Dreyer, Rosenkranz & Droop (DRD) was a major German manufacturer of water meters and precision measuring instruments founded in 1870 in Hannover, and active well into the mid‑20th century.

🏭 Origins and Founding (1870–1875)

Founded in 1870 by Philipp Hermann Rosenkranz, together with partners Ernst August Dreyer and Adolf Droop.

Rosenkranz had previously worked at Schäffer & Budenberg, one of Europe’s most important early instrument makers.

The firm began operations in Hannover, initially producing manometers, thermometers, and mechanical measuring instruments.

By 1875, DRD was already exhibiting advanced water meters, including a reaction‑turbine‑based design described in the Polytechnich Journal. This design aimed to combine the simplicity of turbine meters with the accuracy of piston meters.

💧 Water Meter Development

DRD became known for innovative water meter engineering, including:

- Reaction turbine meters with improved sensitivity and accuracy.

- A hybrid design combining turbine simplicity with piston‑like sealing, using a ring‑shaped flow channel and rotating flügel (vanes) connected to a counting mechanism.

Their meters were widely used in municipal and industrial applications across Germany by the late 19th century.

Grace’s Guide also lists DRD as a recognized water meter manufacturer in 1886, confirming their established role in the sector.

📈 Growth, Industrial Expansion & Corporate Evolution (1880s–1940s)

By 1892, the company was a significant Meßgerätefabrik (instrument factory) with a growing product line including pressure regulators, gauges, and water‑meter test stations.

In 1922, DRD became a publicly listed company (AG), reflecting its scale and capitalisation.

Headquarters and main works were located at Leisewitzstr. 4–50, Hannover, with a large factory complex beside the railway.

By the 1930s, DRD operated branches in Berlin, Essen, and Hamburg, and maintained international representation.

Their 1937 production program included:

- Water meters

- Water‑meter test stations

- Manometers & thermometers

- Pressure‑reducing valves

🏢 Late 20th‑Century Changes

DRD later merged with H. Meinecke AG, forming H. Meinecke AG – Dreyer, Rosenkranz & Droop AG, with a branch in Rethen.

In 1970, the company became part of OTA Industriegeräte GmbH, Frankfurt.

By the late 1970s, it operated as DRD Mess‑ und Regeltechnik GmbH, though by around 2014 the firm was no longer traceable online.

🧭 Summary

Dreyer, Rosenkranz & Droop stands out as:

One of Germany’s earliest and most technically sophisticated water‑meter manufacturers.

A company that bridged turbine and piston metering technologies.

A long‑lived industrial firm (1870–1970s) with major contributions to precision measurement, municipal water metering, and instrument engineering. Pictured below is an extremely rare DRD prototype 3/4" water meter in this museum's collection. Research -Alex Manu 05/2026