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SAT - Site Acceptance Test
A test of equipment carried out at site following installation of equipment but prior to commissioning.

Further Reading

 


SCADA
Supervisory Control and Data Acquisition - A term commonly used to describe a PC based software package that allows operator control of a process from a PC and has the PC collecting and storing process information.
Often used with PLCs.
Further Reading

 


Scale Factor
The factor by which the number of scale divisions indicated or recorded by an instrument must be multiplied to compute the value of a measured variable.

Further Reading

 


SCE
Safety Critical Element

Further Reading

 


scf - Standard Cubic Feet
Pronounced scuf - a measurement of gas e.g. 20 MMSCF/hr being 20 thousand cubic feet per hour

Further Reading

 


Sensitivity
The minimum change in a physical variable to which an instrument can respond.

Further Reading

 


Sensor
An element or device that detects a variable by receiving information in the form of one quantity and converting it to information in the form of that or another quantity.

Further Reading

 


Setpoint
A variable - expressed in the same units as the measurement - which sets either the desired target for a controller or the condition at which alarms or safety interlocks are to be energised.

Further Reading

 


Signal to Noise Ratio
Ratio of signal amplitude to noise amplitude.

Further Reading

 


SIL - Safety Integrity Level
A discrete level (1 to 4) for specifying the safety integrity requirements of the safety functions to be allocated to a loop.
SIL 4 being most onerous.
Further Reading
SIL Ratings Toolbox Page
 


SoR
Statement of Requirements

Further Reading

 


Sour
A sour fluid is a fluid that contains hydrogen sulphide (H2S) at 10 ppm or more.

Further Reading

 


SOV
Solenoid Operated Valve

Further Reading

 


SOx - Sulphur Oxides
Sulphur oxide gases (principally Sulphur dioxide - SO2) are formed when fuel e.g. coal and oil; containing sulphur is burned.

Further Reading

 


Span
The algebraic difference between the upper and lower range values expressed in the same units as the range.

Further Reading

 


Stability
The ability of an instrument or sensor to maintain a consistent output when a constant input is applied.

Further Reading

 


Steady State
A characteristic of a condition e.g. value; rate; periodicity or amplitude exhibiting only negligible change over an arbitrary long period of time.

Further Reading

 


Stellite
Cobalt based alloy commonly applied as coating to valve trims to provide high resistance to wear; corrosion and high temperatures.

Further Reading

 


Stonewall
The maximum stable flow and maximum head condition for a centrifugal compressor.

Further Reading

 


STP - Standard Pressure and Temperature
STP is used in many thermodynamic calculations and tabulations and is defined as 0 degrees Celsius and 1 atmosphere of pressure.

Further Reading

 


Surge
An unstable operating condition when the flow through a compressor is decreased to the point that momentary flow reversals occur.
Can lead to major damage of compressor.
Further Reading

 


Synchronous
An event or action that is synchronized to a reference clock.

Further Reading

 

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