Damps Flashcards
Black Damp
Definition: an atmosphere depleted of oxygen by oxidation of coal and carbonaceous material, and containing variable mixtures of nitrogen and carbon dioxide. A typical mixture is from 15 percent CO2 with 85 to 90 percent N2. Also formed by mine fires and explosion of fire damp or coal dust and hence forms part of the “after damp”. Terms sometimes apply to CO 2 or to “Strata gas”, essentially CO2 which may be accompanied by methane and a little nitrogen.
Remarks:
Fire damp
Definition: A combustible gas formed by decomposition or distillation of coal or other carbonaceous matter and consisting chiefly of methane
Remarks: See methane. Usually lighter than air. Can accumulate in unventilated mine workings and issue when the barometer falls. Produced in mine fires by distillation of coal. Can be the principal constituent of outbursts and of issues from mine strata including floor. Sometimes just called “gas” and a “gassy” mine or place is one in which fire damp is found.
Choke damp
Definition: A mine atmosphere that causes choking or suffocation due to insufficient oxygen, e.g: large emissions from coal or strata of gases such as methane or carbon dioxide displacing air. Hence a name sometimes given in England to carbon dioxide.
Remarks: As applies to “air” that causes choking, does not mean any single gas or combination of gases. A choking sensation could be caused by a mine fire using up the air or by the presence of smoke or oxides of sulphur in a smoky atmosphere.
Illawarra gas
Definition: A mixture of methane and CO2 (or “Black damp”) ranging from almost pure CO2 to almost pure methane, with a little nitrogen. When this mixture, issuing from the seams, is predominantly CO owing to its high density if it is not mixing with air it may flow along the floor, hence the term “Illawarra bottom gas”.
Remarks:
After damp
Definition: The mixture of gases which remains in a mine after a mine fire or an explosion of fire Damp or coal dust.
Remarks: it consists of Carbon Dioxide, nitrogen, water vapour, oxygen, carbon monoxide (and in some cases free hydrogen, methane and miscellaneous other gases from the distillation of coal after a mine fire), but usually consists principally of carbon dioxide and nitrogen, and therefore die not support life.
White damp
Definition: Term applies to carbon monoxide, or atmospheres containing lethal quantities of carbon monoxide.
Remarks: A gas that may be present in the “after damp” of a gas or coal dust explosion, or in the gases given off by a mine fire; also one of the constituents of the gases produced by blasting; and a constituent of “water gas”, “producer gas” and coal gas. Low concentrations found in coal mine atmosphere as a gas occluded and given off the coal. Any increase, even slight, from a normal concentration is an indication on incipient heating.
Stink damp
Definition: hydrogen sulphide or mixtures of hydrogen sulphide and air or other gases with the odour of H2S predominating
Remarks:
Fire damps
Definition: Terms applied to the smell indicating spontaneous combustion in a coal mine. Benzene of our often associated.
