An analyser or analyzer is a tool used to analyze data. For example, a gas analyzer tool is used to analyze gases. It examines the given data and tries to find patterns and relationships. An analyser can be a piece of hardware or software. Autoanalysers perform their work with little human involvement.

Operation

Analysis can be done directly on samples or the analyser can process data acquired from a remote sensor. The source of samples for automatic sampling is commonly some kind of industrial

process A process is a series or set of activities that interact to produce a result; it may occur once-only or be recurrent or periodic. Things called a process include: Business and management *Business process, activities that produce a specific se ...

. Analysers that are connected to a process and conduct automatic sampling, can be called online (or on-line) analysers or sometimes inline (or in-line) analysers. For inline analysis, a sensor can be placed in a process vessel or stream of flowing material. Another method of online analysis is allowing a sample stream to flow from the process equipment into an analyser, sometimes conditioning the sample stream e.g., by reducing

pressure Pressure (symbol: ''p'' or ''P'') is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled ''gage'' pressure)The preferred spelling varies by country a ...

or changing the sample

temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied on ...

. Many analysers are not designed to withstand high pressure. Such sampling is typically for

fluid In physics, a fluid is a liquid, gas, or other material that continuously deforms (''flows'') under an applied shear stress, or external force. They have zero shear modulus, or, in simpler terms, are substances which cannot resist any shea ...

s (either liquids or gases). If the sample stream is not substantially modified by the analyser, it can be returned to the process. Otherwise, the sample stream is discarded; for example, if reagents were added. Pressure can be lowered by a pressure reducing

valve A valve is a device or natural object that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. Valves are technically fitting ...

. Such valves may be used to control the

flow rate Flow rate may refer to: * Flow measurement, a quantification of bulk fluid movement * Mass flow rate, the mass of a substance which passes per unit of time * Volumetric flow rate, the volume of fluid which passes per unit time ** Discharge (hydrol ...

to the online analyser. The temperature of a hot sample may be lowered by use of an online sample cooler. Analysis can be done periodically (for example, every 15 minutes), or continuously. For periodic sampling,

s (or other devices) can be switched open to allow a fluid sample stream to flow to the analyser and shut when not sampling. Some methods of inline analysis are so simple, such as

electrical conductivity Electrical resistivity (also called specific electrical resistance or volume resistivity) is a fundamental property of a material that measures how strongly it resists electric current. A low resistivity indicates a material that readily allows ...

or pH, the instruments are usually not even called analysers.

Salinity Salinity () is the saltiness or amount of salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensionless and equal ...

determined from simple online analysis is often determined from a conductivity measurement where the output signal is calibrated in terms of salinity concentration (for example ppm of NaCl). Various types of other analyses can be devised. Physical properties can include

(or effectively

electrical resistivity Electrical resistivity (also called specific electrical resistance or volume resistivity) is a fundamental property of a material that measures how strongly it resists electric current. A low resistivity indicates a material that readily allows ...

refractive index In optics, the refractive index (or refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium. The refractive index determines how much the path of light is bent, o ...

, and radioactivity measurement. Simple processes that use inline

determination are

water purification Water purification is the process of removing undesirable chemicals, biological contaminants, suspended solids, and gases from water. The goal is to produce water that is fit for specific purposes. Most water is purified and disinfected for hu ...

processes which test how effectively

salts In chemistry, a salt is a chemical compound consisting of an ionic assembly of positively charged cations and negatively charged anions, which results in a compound with no net electric charge. A common example is table salt, with positively ...

have been removed from the output water. Electrical conductivity variations include

cation An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conve ...

and

anion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conve ...

conductivity.

Chromatography In chemical analysis, chromatography is a laboratory technique for the separation of a mixture into its components. The mixture is dissolved in a fluid solvent (gas or liquid) called the ''mobile phase'', which carries it through a system ( ...

such as ion chromatography or

HPLC High-performance liquid chromatography (HPLC), formerly referred to as high-pressure liquid chromatography, is a technique in analytical chemistry used to separate, identify, and quantify each component in a mixture. It relies on pumps to pa ...

often tests the output stream continuously by measuring electrical conductivity, particularly cation or anion conductivity, refractive index,

colorimetry Colorimetry is "the science and technology used to quantify and describe physically the human color perception". It is similar to spectrophotometry, but is distinguished by its interest in reducing spectra to the physical correlates of color ...

or ultraviolet/visible

absorbance Absorbance is defined as "the logarithm of the ratio of incident to transmitted radiant power through a sample (excluding the effects on cell walls)". Alternatively, for samples which scatter light, absorbance may be defined as "the negative lo ...

at a certain

wavelength In physics, the wavelength is the spatial period of a periodic wave—the distance over which the wave's shape repeats. It is the distance between consecutive corresponding points of the same phase on the wave, such as two adjacent crests, tr ...

. InlineOnline and offline analysers are available for other types of

analyte An analyte, component (in clinical chemistry), or chemical species is a substance or chemical constituent that is of interest in an analytical procedure. The purest substances are referred to as analytes, such as 24 karat gold, NaCl, water, et ...

s. Many of these add reagents to the samples or sample streams.

Types of analysers

* Automated analyser * Bus analyser * Differential analyser – early analogue computer *

Electron microprobe An electron microprobe (EMP), also known as an electron probe microanalyzer (EPMA) or electron micro probe analyzer (EMPA), is an analytical tool used to non-destructively determine the chemical composition of small volumes of solid materials. It ...

* Lexical analyser *

Logic analyser A logic analyzer is an electronic instrument that captures and displays multiple signals from a digital system or digital circuit. A logic analyzer may convert the captured data into timing diagrams, protocol decodes, state machine traces, asse ...

* Network analyser * Protocol analyser (packet sniffer) * Quadrupole mass analyser * Spectrum analyser *

Vector signal analyser A vector signal analyzer is an instrument that measures the magnitude and phase of the input signal at a single frequency within the IF bandwidth of the instrument. The primary use is to make in-channel measurements, such as error vector magnitud ...

References

{{Reflist Measuring instruments