High Level Instrumentation |
Instrumentation is the use of measuring instruments to monitor and control a process. It is the art and science of measurement and control of process variables within a production, laboratory, or manufacturing area.
An instrument is a device that measures a physical quantity such as flow, temperature, level, distance, angle, or pressure. Instruments may be as simple as direct reading thermometers or may be complex multi-variable process analyzers. Instruments are often part of a control system in refineries, factories, and vehicles For example, a smoke detector is a common instrument found in most western homes.
Measurement instruments have three traditional classes of use:
1.Monitoring of processes and operations
2.Control of processes and operations
3.Experimental engineering analysis.
Measurement:- The first proposal to tie an SI base unit to an experimental standard independent of fiat was by Charles Sanders Peirce (1839–1914), who proposed to define the metre in terms of the wavelength of a spectral line.
Any measurement of an object can be judged by the following meta-measurement criteria values: level of measurement (which includes magnitude), dimensions (units), and uncertainty. They enable comparisons to be done between different measurements and reduce confusion.Even in cases of clear qualitative similarity or difference, increased precision through quantitative measurement is often preferred in order to aid in replication.
The seven base units in the SI system. Arrows point from units to those that depend on them; as the accuracy of the former increases, so will the accuracy of the latter |
Artifact-free definitions fix measurements at an exact value related to a physical constant or other invariable phenomenon in nature, in contrast to standard artifacts which can be damaged or otherwise change slowly over time.
The original SI units for the six basic physical quantities were
Base quantity
|
Base unit
|
Symbol
|
Current SI
constants
|
New SI constants
(proposed)[6]
|
time
|
second
|
s
|
hyperfine splitting in Cesium-133
|
same as current SI
|
length
|
metre
|
m
|
speed of light in vacuum, c
|
same as current SI
|
mass
|
kilogram
|
kg
|
mass of International Prototype
Kilogram (IPK)
|
Planck's constant, h
|
electric current
|
Ampere
|
A
|
permeability of free space, permittivity of
free space
|
charge of the electron, e
|
temperature
|
Kelvin
|
K
|
triple point of water, absolute zero
|
Boltzmann's constant, k
|
amount of substance
|
mole
|
mol
|
molar mass of Carbon-12
|
Avogadro constant NA
|
luminous intensity
|
candela
|
cd
|
luminous efficacy of a 540 THz source
|
same as current SI
|
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