SAFETY VALVE -- A spring loaded valve that
automatically opens when pressure attains the valve setting. Used to prevent
excessive pressure from building up in a boiler.
SAFETY VALVE BLOWDOWN -- The difference between the pressure
at which a safety valve opens and at which it closes.
SATURATED STEAM -- Steam at the same temperature as the water
from which it was formed.
SATURATED TEMPERATURE -- The temperature at which evaporation
occurs at a particular pressure.
SATURATED WATER -- Water at its boiling point.
SAVANNA -- Some people claim that the American Ship Savannah
was the first steamship to cross the Atlantic Ocean in 1819. The Steamship
Savannah was on of the sailing ships fitted with a steam boiler, a steam engine
and a pair of side-wheels. During her twenty-nine days voyage they used the
steam engine less than four days. I don't consider that a steamship voyage.
After that voyage the engine was removed and the steamship Savanna continued
her days as a sailing ship.
The Steamship Curaçao, a Dutch mail Steamship crossed de Atlantic Ocean
several times, mostly under steam power, in 1826-28. That I call
steamship voyages.
SCALE -- Incrustation, a hard coating of
deposits precipitated from solution at the boiler tube surface.
SCOTCH MARINE BOILER -- Fire-tube boiler equipped
with an internal furnace, fire chamber and return tubes completely surrounded
by water. The design originated from the Scottish Clyde Shipyard.
SCREW PROPELLER -- A boss, carrying 2, 3, 4 or more blades of
helical form, that produces the thrust to drive a ship by giving momentum to
the column of water which it displaces in an astern direction.
In the end of 1850 the screw propeller become recognized as superior to the
paddle-wheels and after that the screw-propelled ships began to supersede the
sailing ships. Steamships with screw propellers have a number of advantages and
these ships are better in rough sea since the screw is continually
submerged.
SENSIBLE HEAT -- That heat which effects a change in a body
that is detectable by the senses; i.e. it causes the temperature of the body to
change. Measured by the product of the specific heat capacity, the mass of the
body and the change of temperature.
SHIPS versus BOATS -- To distinguish between ships and boats:
If her length is 12m or more and her beam is 4m or more then she is a
Ship otherwise she is a Boat.
SIGHT GLASS -- The gauge glass and its fittings for
attachment.
SIDE-WHEELER Paddle Steamships with
a paddle-wheels at each side of the hull and the wheels mounted on the very
same shaft. Side-wheelers can carry less cargo than Screw-propelled steamships
since there draught will influence on the paddle-wheels efficiency. If the
wheels are too much submerged they will not work at all.
SILICA -- Except in a few sections, this impurity in the
boiler water is not troublesome.
SKIMMING -- Procedure for cleaning the surface of the water in
a boiler. This procedure should be done on all new boiler installations, and
when there is a foaming condition.
SL -- Steam Launch.
SLIDE-VALVE -- A steam engine inlet and exhaust valve shaped
like a rectangular lid. It is reciprocated inside the steam chest, over a face
in which steam ports are cut, so as alternatively to admit steam to cylinder
and connect the ports to exhaust through the valve cavity.
SLUDGE -- A soft, water-formed sedimentary deposit that can
usually be removed by bottom blowdown. Also a common name for waste-oil.
SMOKE BOX -- The smoke box is where the flue tubes ends. The
smoke accumulates here before being vented out through the funnel.
SODIUM SALTS -- In some water supplies, particularly near the
sea, sodium chloride occurs in large quantities. The chief difficulties caused
by the sodium salts are priming and foaming, due to their concentration in the
boiler, the remedy for which is more frequent blowing down.
SOFT WATER -- Water which contains little or no calcium or
magnesium salts.
SOFTENING -- The act of reducing calcium and magnesium
impurities from water.
SOOTBLOWER -- A device to clean heat absorbing
surfaces.
SPECIFIC LATENT HEAT -- The heat which is required to change
the state of a substance from solid to liquid, or from liquid to gas, without
change of temperature. The numerical value of the specific latent heat is the
amount of heat required to change the state of unit mass. Most substances have
a latent heat of fusion (melting) and a latent heat of evaporation. In
thermodynamics, heat supplied at constant pressure is called enthalpy, and thus
specific latent heat of evaporation is called enthalpy of evaporation.
SPRAY NOZZLE -- A nozzle from which a liquid fuel is
discharged in the form of a spray.
SS -- Steamship.
STAYBOLT -- Bolt used in boilers to reinforce flat surfaces
subjected to boiler pressure.
STEAM ATOMIZING OIL BURNER -- A burner for firing
oil that is atomized by steam. It may be of the internal or external mixing
type.
STEAM CHEST -- The chamber in which the slide-valve of a steam
engine works, and to which the steam pipe is connected.
STEAM DRUM -- The upper drum of a water tube boiler where the
separation of water and steam occurs. The steam outlet line normally takes off
from this drum.
STEAM JACKET -- A jacket formed round a steam-engine cylinder;
supplied with live steam to prevent excessive condensation of the working steam
in the cylinder.
STEAM LAP -- The amount by which the slide-valve of a
reciprocating steam-engine overlaps the edge of the steam ports when in
mid-position. Also called Outside lap.
STEAM POP SAFETY VALVE -- A spring loaded valve that
automatically opens when pressure attains the valve setting. Used to prevent
excessive pressure from building up in a boiler.
STEAM PORTS -- Passages leading from the valve face of the
cylinder of a reciprocating steam engine; through them the steam is supplied
and exhausted.
STEAM SEPARATOR -- A device inside the steam drum that is used
to prevent water from passing over with the steam.
STEAMSHIP PREFIX -- A steamship usually carry a prefix before
her name:
SS Steamships
PS Paddle Steamer
TS Turbine Steamship
SL Steam Launch
NS Nuclear Ship
RMS Royal Mail Steamship
STEAM TRAP -- A device into which condensed steam from steam
pipes, etc., is allowed to drain, and which automatically ejects without
permitting the ejection of steam.
STEERING ENGINE -- A steam-engine
used to turn the ships rudder to match the steering-wheel's position.
STERN-WHEELER -- Paddle Steamships with a paddle-wheel at the
stern. The Mississippi River Stern-wheelers have a steering system that is very
different from other ships. On a screw propelled ship, the rudder is behind the
propeller. A stern-wheeler has its two very large rudders ahead of the
paddle-wheel. This makes these ships more manoeuvrable in astern than ahead
going.
STOICHIOMETRIC COMBUSTION -- Perfect combustion.
The complete oxidation of all the combustible constituents of a fuel, utilizing
all the oxygen supplied.
STOKEHOLD -- Compartment in
which steamer's fires are tended.
STOKEHOLE -- Space for stokers in front of furnace.
STOKER -- A mechanical device that feeds coal to a furnace, or
a man who feeds and tends the furnaces of a steamer.
STOP VALVE -- Valve that is used to isolate a boiler from the
other parts.
SUPERHEATED STEAM -- Steam heated at constant pressure out of
contact with the water from which it was formed, i.e., at a higher temperature
than that of saturation.
SUPERHEATER
-- A bank of tubes, in the exhaust gas duct after the boiler, used to heat the
steam above the saturation temperature.
SURFACE BLOW VALVE -- A valve with pipe connections to the
interior of the boiler and overboard, used for the purpose of blowing off the
scum and grease that collect on the surface of the water.
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