blower
A fissure from which firedamp issues, often in quantity for many years.
blower: a coal seam vent that won't stop leaking gas
A blower is a persistent natural opening in a coal seam or adjacent strata from which firedamp (a mixture of methane and air) issues continuously, often in large volumes and over many years. Unlike the ordinary seepage found throughout most mines, a blower is a localized, active source that can pour thousands of cubic feet of gas per day into the working atmosphere.
Blowers occur where geological fractures, faults, or cleats in the coal have opened pathways to deeper gas-bearing zones. Once established, they are difficult to seal. The gas flows under natural pressure difference between the deeper formation and the mine air. Some blowers have been recorded as active for decades; the gas volume may fluctuate with atmospheric pressure, water table changes, or barometric conditions, but the source remains fundamentally open.
Detection and Management
A blower is identified by its steady or pulsing outflow of gas, typically detected by flame safety lamps showing a persistent cap or by portable gas monitors recording elevated methane near a specific point. The critical hazard is not a single massive release but the relentless contamination of the local working area. In confined spaces, even modest volumetric flow can render the air explosive if ignition sources are present.
Mine operators respond by increasing ventilation to that area, isolating the site if necessary, or attempting partial sealing with resin or cement injections. However, high-pressure blowers often defeat sealing attempts. Historical practice was to work around them, maintaining higher air flow through the affected district and keeping careful watch. Modern mines may retreat from areas with large uncontrolled blowers rather than risk the cumulative hazard.
The term appears primarily in British and European mining literature and reflects the era when coal mines had to adapt to such features as fixed geological facts. A blower is distinct from a sudden outburst (a violent release) and from the continuous low-level degassing of coal; it is the intermediate case: chronic, significant, and impossible to ignore.