Next page Previous page

self-contained self-rescuer

A respiratory device used by miners for the purpose of escape during mine
fires and explosions; it provides the wearer a closed-circuit supply of
oxygen for a minimum of 10 min and up to 1 h. Syn:SCSR

self-diffusion

The spontaneous movement of an atom to a new site in a crystal of its own
species, such as a copper atom within a crystal of copper. ASM, 1

self-dumping cages

Cages in which the cars are generally fitted with end doors; the cage deck
is pivoted, and a roller engages with a tipping guide at the surface. As
the cage is lifted, toward the end of the wind the deck tilts, the end
door is lifted, and the coal is discharged. Sinclair, 5

self-dumping car

A mine car that can be side-tipped while in motion on a rail track. A ramp
structure is fitted alongside the track opposite the spot where tipping is
required. The car is fitted with a spherically contoured wheel that
engages the ramp and gradually tilts the car while in motion. A chain
attachment to the underframe opens the side of the car when tilted for
tipping. The ramp can be retracted when not required. Nelson

self-energizing brake

A brake that is applied partly by friction between its lining and the
drum. Nichols, 1

self-feeder

An automatic appliance for feeding ore to stamps or crushers without the
employment of hand labor. Fay

self-feeding portable conveyor

Any type of power-propelled conveyor designed to advance into a pile of
bulk material, thereby automatically feeding itself.

self-fluxing ores

Ores that contain both acid and basic gangue minerals in the proper ratio
to form a suitable slag. Newton, 1

self-inductance

The property of a circuit whereby self-induction occurs. It is measured by
the rate of change of linkages in a circuit that accompanies a rate of
change of current in that circuit of one unit per second. CTD

self-issue system

A system of storage in lamp-room-operation charging and issue for
alkaline-type car lamps, that allows a user access only to the storage
racks for the purpose of lamp collection or return. Charging is controlled
by a lamp-room attendant. BS, 13

self-loading dumper

A dumper provided with a bucket, hinged by arms to the chassis, that
scoops up the material and discharges it backwards into the hopper.
Hydraulic rams control the lift arms, bucket movement, and dumping
operation. Nelson

self-opening reamer

An underreamer having cutters that expand when they come in contact with,
and are pressed against, surface. CF:expansion bit; underreamer.
Long

self-potential

See:spontaneous

self-potential curve

See:spontaneous potential curve

self-potential log

Strip recording of natural potentials of complex origin, arising in the
immediate neighborhood of liquid-filled boreholes.
See also:electric logging

self-potential method

An electrical exploration method in which one determines the spontaneous
electrical potentials (spontaneous polarization) that are caused by
electrochemical reactions associated with clay or metallic mineral
deposits. Syn:spontaneous-potential method

self-potential prospecting

A method of electrical prospecting based on the measurement of natural
earth potentials caused by the self-potential effects from orebodies,
commonly metallic sulfides. AGI

self-powered scraper

A scraper built into a single unit with a tractor. Nichols, 1

self-priming centrifugal pump

A pump of the centrifugal type that combines in a single hydraulic stage
and with a single hydraulic impeller and casing the dual ability to pump,
under vacuum, either liquids or gases. These pumps are advantageously used
for sump, bilge, mine water gathering, tankcar unloading, vacuum
evaporator applications, chemical processing, and other uses where the
liquid is below the pump centerline, or under high vacuum. The suction
lift is usually guaranteed at 20 ft (6.1 m) for cold water at sea level.
Pit and Quarry

self-reading staff

A leveling staff, marked with graduations so that an observer looking
through the telescope of a level can read the elevation at which his or
her line of sight intersects the staff. Hammond

self-rescuer

A small filtering device carried by a miner underground, either on a belt
or in a pocket, to provide the miner with immediate protection against
carbon monoxide and smoke in case of a mine fire or explosion. The device
is used for escape purposes only because it does not sustain life in
atmospheres containing deficient oxygen. The length of time a self-rescuer
can be used is governed mainly by the humidity in the mine air; e.g., in
moist air it will last for a minimum period of 30 min, and in moderately
dry atmospheres, for a period of 1 h or more.
See also:Siebe-Gorman self-rescuer