Sacrificial Anode - A piece of metal buried near a structure that is to be protected from corrosion. The metal of the sacrificial
anode is intended to corrode and reduce the corrosion of the protected structure.

SAE Steel - Steel manufactured under the specifications by the Society of Automotive Engineers.

Sag - Deflection due to gravity acting on a cantilevered or otherwise supported object.

Sandblasting - A process of blowing sand by compressed air with considerable force through a hose against an object.

SCADA - Supervisory control and data-acquisition

Scraper - A hardened steel hand tool used to scrape surfaces very smooth by removing minute amounts of metal.

Screw - A helical projection of uniform section on the internal or external surface of cylinder or cone.

Screw Thread - A ridge of constant section which is manufactured so that a helix is developed on the internal or external
surface of a cylinder.

Second Class Lever - The load is situated between the fulcrum and the applied force.

Sedimentation - The gravity settling, and thus removal, of materials more dense than the suspending fluid

Self Extinguishing - A material which will not support combustion when external source of flame is removed.

Self-Inductance - Inductance that produces an induced voltage in itself as the result of a change in current flow

Semiconductor - A material that has a limited capacity for conducting an electric current. The most common semiconductor
materials are silicon and germanium. Computer chips, both for CPU and memory, are composed of semiconductor materials.
Semiconductors make it possible to miniaturize electronic components, such as transistors.

Service Drag - This is drag from air ducted to cooling components.

Set Screw - A plain screw used principally for locking adjustable parts in position.

sg - Specific gravity.

Shake Table Test - A laboratory test for vibration tolerance, in which the device to be tested is placed on a vibrator.

Shaker - An electromagnetic device capable of imparting known vibratory acceleration to a given object.

Shank - That part of a tool or similar object which connects the principal operating part to the handle, socket, or chuck by
which it is held or moved.

Shear Modulus - The shear modulus is related to the Young's modulus and Poisson′'s ratio.

Shear Stress - Stress in the cross-sectional plane of a material that is in the same plane as the shearing force acting on it.

Shim - A thin sheet of metal or other material which is inserted between two machine parts to obtain their correct relative
location.

Shop Drawings - Drawings submitted by a contractor or vendor to an engineer to show dimensions, specifications, etc.

Shot Blasting - Cleaning surface of metal by air blast, using metal shot as an abrasive.

Shrinking Hammer - A special hammer with faces shaped to allow for correction of locally stretched sheet metal.

SiC - Silicon Carbide, used extensively as a grinding compound and in abrasive wheels.

Side Cutters - A tool like a pair of pliers except the end opposite the handles have sharp edges used to cut wire.

Silencer - An acoustic filter element used to reduce sound pressure levels inside a duct.

Single Cylinder Engine - The first internal combustion engines were single cylinder designs and mostly stationary engines.

Single Phase Flow - The flow of a material, as a gas, single-phase liquid, or a solid, but not in any combination of the three.

Single-pole, double-throw (SPDT) switch - A switch that in one position completes one of two circuits. In the second position
the switch completes a second circuit and breaking the first circuit

Site Analysis  - An analysis performed to determine if a site is suited for the intended facility

Site Plan - Drawings that provide an overhead perspective on how facilities would appear on a site.

Skin Friction - This is drag due to the surface texture and area.

Slide Hammer - A tool with a long round shaft on which a hammer weight slides.

Sludge - A mixture of solid waste material and water

Soft Solder - Solder composed of 50% Tin and 50% Lead

Solder - A low melting point alloy that can wet copper, conduct current, and mechanically join conductors.

Soldering - Process of joining metallic surfaces with solder without melting the base material.

Spall - Small chips or fragments which are sometimes given off by electrodes during the welding operation.

Spanner - A tool used to turn a nut and bolt. Wrench is another name for spanner.

Specific Gravity - The ratio of mass of any material to the mass of the same volume of pure water

Specific Heat - The ratio of thermal energy required to raise the temperature of a body 1 degree to the thermal energy
required to raise an equal mass of water 1 degree.

Speculum - A copper-tin alloy with 33 to 45% of tin that has very high optical reflectivity when polished.

Spindle - Another name for an axle.

Spindle Speed - The rotational speed at which a machine is set.

Spirit Level - A tool for testing if a surface is level using a glass tube containing an air bubble.

Split Pin - A metal pin with two arms which is passed through a hole and held in place by the springing apart of the arms.

Springs - The physics of simple springs - helical and beam forms.

Spur Gear - A gear having teeth parallel to the axis of the shaft on which it is mounted.

St - Stokes, the CGS unit of kinematic viscosity.

Stainless Steel - Any steel containing at least 10.5% Cr as the principal alloying element.

Standard Temperature and Pressure - Often abbreviated as stp or STP it is a temperature of 0°C and a pressure of
101325Nm-2.

Standard Wire Gauge - A numbering system for standard wire diameters, often abbreviated as SWG.

Static Equilibrium - Equilibrium which does not include inertial forces.

Static Pressure - Pressure of a fluid whether in motion or at rest.

Statically Determinate - A statically determinate structure is one where there is only one distribution of internal forces and
reactions which satisfies equilibrium.

Statically Indeterminate - A statically indeterminate structure is one where there is more than one distribution of internal
forces and/or reactions which satisfies equilibrium.

Statwatt - The unit of power in the obsolete electrostatic system of units.

Steam Engine - An engine that uses steam to produce useful work.

Steam Turbine - A turbine driven by steam expansion through the blades of the turbine.

Steel - An iron-based alloy containing manganese, usually carbon, and other alloying elements.

Steering Offset - The distance from the point where the steering axis intersects the ground to the longitudinal line that runs
through the centre of the tyre′s contact patch.

Step Stressing - stresses in a series of pre-selected increments.

Stiction - Can be defined as a form of friction which is resistance to the start of movement.

Stiffness - The ratio of change of force (or torque) to the corresponding change in translation (or rotational) deflection of an
elastic element.

Stirling Engine - An external combustion engine.

Stokes - The CGS unit of kinematic viscosity. Abbreviated as St. 1St=1x10-4m2s-1.

Strain - The ratio of the change in length to the initial unstressed reference length.

Strain Gauge - A sensor that experiences a change in resistance when it is stretched or strained.

Stress - Force per unit area

Stress Resultant - A system of forces which is statically equivalent to a stress distribution over an area.

Stoichiometric - The exact percentage of two or more substances which will react completely with each other leaving no
unreacted residue.

Stroke - The distance a piston travels up or down inside the cylinder.

Structural Model - An idealization for analysis purposes of a real or conceived structure.

Stud - A fastener which is threaded at both ends with an unthreaded shank in between.

Substation - Equipment assembly containing switches, circuit breakers, buses and transformers for switching power circuits
and to transform power to a voltage suitable for transmitting or distributing power

Subsynchronous - Component of a vibration signal thathas a frequency less than shaft rotation frequency.

Supercharger - An air compressor used to force more air into an engine than it can inhale on its own.

Support - Contributes to keeping a structure in place by restraining one or more degrees of freedom.

Surface Force - A force applied to the surface of an object.

Surface Gauge - A gauge used to check the accuracy, of plane surfaces, to scribe lines at desired distances from a given
surface and to check the height of a point or points on a piece of work from a given surface.

Surface Roughness - At a microscopic scale, no surface appears perfectly smooth.

Surface Tension - Small droplets or bubbles of one fluid immersed in another fluid have a spherical shape because of the
interfacial tension, or surface tension, between the two fluids.

SWG - A numbering system for standard wire diameters.

Symmetrical Thread - Both flanks of the thread profile are inclined at the same angle.
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