Trompe

A water drum, also called wind trumpet, is a machine design that has been used in mining for artificial ventilation. 1558 there is a mention of a water drum fan in a work of Giambattista della Porta. The water drum was used particularly in the Harz mining area often. It was introduced in the resin of the Clausthal scholars Henning Calvör, she was there therefore also called Calvörsche water drum. For the first time the water drum in 1732 was used in the Harz mining.

Construction

The water drum is made of an open-topped wooden box. This wooden box is equipped with a side discharge. On the floor of this wooden box, a large block of wood is mounted. In this first wooden box is a second smaller wooden box which is open at the bottom. This open-bottomed box is called a bell. In the cover of the bell, there are two holes. One of the holes serves as an air outlet opening. Through this air outlet opening a nozzle is attached. In the other hole of the bell, a case tube is fitted. This drop tube is also made of wood and is provided with a plurality of directed from top to bottom holes. The tube opens at the upper end in another water tank. Although at a greater height of fall, a higher static water pressure is generated, it is not useful in the water drum, to use a larger drop height as 16 feet. For larger drop heights several water drums are successively cascaded.

Function

The upper water tank is constantly filled with water, which then crashes through the downpipe down. The water drawn in through the openings in the drop tube to air. When the water hits the block of wood in the wood box below, it is atomized. In this operation, the entrained air is released. The now released air accumulates below the bell and is slightly compressed by the rising water. This easily compressed air flows out of the air outlet port. From there, the fresh air is blown over a Lutte up in the mine. The inflowing water is discharged through an overflow. Thus, the water drum works optimally, the water has a flow rate of three to four meters per second must reach in the down pipe.

Use

The efficacy ( effectiveness ) in the water drum is located at just 15 percent. For this reason, the use of the water drum was limited only to smaller mines. There were a few small stretches her be weathered. The ventilation of entire mines was not possible with this design. Often used to the effect of the flowing water also by the fact that you let the water fall into a narrow shaft. This beam then ripped the air with it and there was a the same effect as the water drum.