The ratio obtained by dividing useful power output by power input. This is
expressed as a percentage. Fan efficiency is understood to mean that air
power is calculated from volume flowing and total pressure, on the
assumption that the air does not change in volume. The velocity head,
present in the air leaving the evase, is considered as a loss. The power
input is that supplied to the fan shaft and thus includes the loss in the
fan bearings but excludes all losses in the drive.
An electric fan used for the removal of enamel dust from the spray booth,
or fumes from the pickle room, thus safeguarding the health of the worker.
Enam. Dict.
In bituminous coal mining, a person who tends and fires the boiler
generating steam for driving fans used for mine ventilation. DOT
A fold with a broad hinge region and limbs that converge away from the
hinge. AGI
Used for attaching ironwork to timber. The nut is a plate with teeth,
which bite into the wood. To tighten, the bolt is turned while the nut
remains stationary. Crispin
A sedimentary rock consisting of slightly waterworn, heterogeneous
fragments of all sizes, deposited in an alluvial fan and later cemented
into a firm rock; it is characterized by persistence parallel to the
depositional strike and by rapid thinning downdip. AGI
The general fan laws are the same for either axial-flow or centrifugal
fans. These laws are as follows: (1) air quantity varies directly as fan
speed; quantity is independent of air density (twice the volume requires
twice the speed); (2) pressures induced vary directly as fan speed
squared, and directly as density (twice the volume develops four times the
pressure); (3) the fan-power input varies directly as the fan speed cubed
and directly as the air density (twice the volume requires eight times the
power); and (4) the mechanical efficiency of the fan is independent of the
fan speed and density.
Scot. A small portable hand fan. Fay
Frictional pressure drop (Delta pt ) of fluid flowing in a pipe;
Delta pt = 2f(v2 /g)(l/d) , where f is a function of the
Reynolds number, v = rate of flow, g is acceleration due to gravity, l and
d are length and diameter of pipe. Pryor, 3
A specific make of viscosimeter. See also:viscometer
The head, quantity, power, and efficiency to be expected when a fan is
operating at peak efficiency. Hartman, 2
A fault scarplet or small fault scarp entirely in piedmont alluvium or in
an alluvial fan. AGI
a. The ventilating shaft to which a mine fan is connected. BS, 8
b. The spindle on which a fan impeller is mounted. BS, 8
A type of seismic survey in which detectors are laid out along an arc so
that each detector is in a different direction at roughly the same
distance from a single shot point. It was used in the 1920's and 1930's to
detect the presence of shallow salt domes intruding low-velocity
sediments. Syn:arc shooting
a. The total ventilating pressure required to circulate the air through a
mine less the natural ventilation pressure. Also called fan useful
pressure. Nelson
b. The difference between fan total pressure and fan velocity pressure.
Syn:fan static head
The fold structure of an anticlinorium. AGI
Equal to the fan static head plus the velocity head at the fan discharge
corresponding to a given quantity of air flow.
See also:total ventilating pressure
The algebraic difference between the mean total pressure at the fan outlet
and the mean total pressure at the fan inlet. BS, 8
The velocity pressure corresponding to the average velocity at the fan
outlet. BS, 8
S. Afr. The area between Boksburg and Heidelburg, Transvaal, limited in
the north and east by the outcrops or sub-outcrops of the Main Reef, but
not yet limited in the south. Beerman