Natural draught, as is known, is the result of the difference in the weight of the air supplying and discharging air. In accordance with this, the depression of natural draught depends on weight, i.e., on the temperature and air pressure in the outgoing and incoming stream. Moreover, depending on the depression developed by the suction or discharge fan, the air density of the outgoing or incoming jet can vary within significant limits, so that, along with the natural draught formed as a result of heating the air and changing its composition, there is also a natural draught created by the fan and "artificially created natural traction". Currently, in addition to calculation methods, a number of methods are known to directly measure the depression of the natural draught of an existing mine. These methods are associated with changing the ventilation regime of the mine. By blocking the entire air stream with a jumper, you can directly measure the depression of natural draught with a micromanometer, connecting it to both sides of the jumper.
