Mine workings are usually subdivided to form a number of separate
ventilating districts. Each district is given a specified supply of fresh
air and is free from contamination by the air of other districts.
Accordingly, the main intake air is split into the different districts of
the mine. Later, the return air from the districts reunite to restore the
single main return air current at or near the upcast shaft.
See also:compound ventilation; fan drift; regulator. Nelson
A department for the purpose of planning adequate and economic ventilation
for all future projects and to provide frequent information on existing
ventilation systems. Nelson
A door constructed to restrict the flow of ventilation air while
permitting the passage of personnel and equipment. See also:door;
separation door.
Two kinds are available, flexible and rigid ducts. Flexible ducts
generally consist of flexible tubes made from fabrics coated with rubber
or polyvinyl chloride, a nonflammable substance. They are available in
varying lengths. Flexible ducting is suited for face ventilation in a
variety of mining methods. It is suited also to crooked workings of
limited extent. It has a higher resistance and a greater tendency to leak
than rigid ducting. Rigid ducts are made of steel or fiberglass in lengths
suitable for underground transport. This type of duct does not have to be
accurately aligned and is therefore used, in the smaller sizes, in
subsidiary work, particularly in crooked headings. For main tunnels where
leakage must be minimized, flanged joints are used with suitable gaskets.
Roberts, 1
One measure of the efficiency of a mine ventilation system is the ratio of
the total amount of air actually reaching the working faces to the total
amount (volume in cubic feet per minute) of air handled by the fan.
See also:overall ventilation efficiency; thermometric fan test;
ventilation standards; volumetric efficiency. Kentucky
A worker who erects by rough masonry or cement work, partitions of stone,
brick, or concrete blocks to control proper circulation of air through
passageways outby working places. DOT
A plan or drawing, required by law, that shows the ventilation air
currents in a mine and the means of controlling them. BS, 7
When a new mine is projected or a new seam is to be worked from an
existing mine, plans are prepared to show the proposed ventilating system,
including the quantities of air and pressures and the principal appliances
to control and distribute the air. Investigations and calculations are
made to select a fan of the necessary type and size for the ventilation
required. All of this important work comes within the general term
ventilation planning. See also:air requirements; pressure survey;
ventilation survey. Nelson
a. The pressure or head producing ventilation in a mine and measured by
the height of a column of water it will support. The instrument used for
this purpose is a water gage.
b. Pressure producing the flow of air, measured by a water gage, or the
difference in level between the two ends of the water column in a vertical
U-shaped tube, one end of which is connected to the air under
pressure--for example, in the passageway leading to the fan--the other end
being to the atmosphere. In some cases, the ventilating pressure is
reported as meters of water in the U-tube; in other cases, the head is
given in pascals or kilopascals.
See:regulator
The standards prescribed by regulations to provide air underground of a
certain degree of purity. See also:ventilation efficiency
Nelson
See:stopping
a. Systematic observation of air pressure, quantity and quality,
throughout a mine or part of a mine, to allow a detailed analysis of the
ventilation system. Syn:pressure-quantity survey
Sinclair, 1; BS, 8
b. To distribute the air in a mine efficiently and economically,
ventilation surveys are conducted. They may be classified as qualitative,
quantitative, and pressure surveys. Qualitative surveys determine the
proportion of flammable or poisonous gas, or dust, in the air that is
being circulated through the mine. In hot and humid mines, they determine
the conditions of air temperature and humidity. Quantitative surveys
determine the quantity of air being circulated through the mine workings
for a variety of reasons. This is done by measuring the volume of air
passing at different points in the circuit by means of an anemometer, to
investigate the existing air distribution, particularly to the individual
faces; the location of leakage; and the possibility of its reduction or
elimination. Pressure surveys measure the pressure absorbed and the
resistance of the roadways and faces included in the survey. This enables
determination of the power required to circulate the air in the different
sections of the circuit and that is expended in ventilating individual
districts. The total power expended in ventilating the mine may then be
summed and the cost estimated. See also:ventilation planning
Sinclair, 1; BS, 8
A set of standard letters, signs, or marks used on mine ventilation plans
to represent certain appliances or constructions to direct and control the
flow of air underground. Nelson
Sheet steel or canvas piping 12 to 24 in (0.3 to 0.6 m) in diameter for
conducting air to or from a tunnel, hard heading face, or sinking pit. The
tubing extends from an auxiliary fan to within a few yards of the face to
be ventilated. See also:tubing; auxiliary ventilation. Nelson
a. A mechanical apparatus for producing a current of air underground, as a
blowing or exhaust fan.
b. A furnace for ventilating a mine by heating the upcast air.
c. A device for providing fresh air to a room or other space by
introducing outside air or by exhausting foul air. Crispin
See:vent tube
a. Hose or piping conducting air-ejected drill cuttings from the borehole
collar to a point some distance from the drill. Long
b. An exhaust pipe or tube. Long
c. Tubing suspended from a wire in a mine opening to supply fresh air to a
working place. Syn:vent pipe
Tubes of steel, fiberglass, or coated fabric with thin walls that can be
easily connected. They are used in mine ventilation to lead air wherever
it is needed. Also called ventilation tubing. Stoces
A contraction in a tube or duct to accelerate the flow and lower the
static pressure. It is used for metering and other purposes.
a. A device resembling a Venturi meter that directs a jet of compressed
air for ventilating short headings. The device is commonly made at a mine,
and one well-proved type is called the Modder Deep. These blowers are
mainly used in conjunction with ventilation ducting for the ventilation of
headings several hundred feet in length. Roberts, 1
b. An apparatus to induce a flow of air or gas in a duct by means of a jet
of compressed air or water from a small nozzle in the duct. BS, 8