Industrial monitoring

Industry in general requires user-friendly equipment for industrial monitoring without the need for expertise for operation and data interpretation. Equipment and techniques that do require corrosion expertise will therefore, be limited to a service , i.e. specialist, company providing both equipment and personnel on a contract basis. 

Polarisation resistance This technique, sometimes referred to as linear polarisation resistance (LPR), has been applied widely in industrial monitoring because of its ability to react instantaneously to a corrosion situation or change in corrosion rate " " . The limitation of the technique arises from the necessity to have a defined electrolyte as the corrosive (the author has seen an LPR probe installed in a dry gas-line in an oil refinery). 

Galvanic current Measurement of the galvanic current between two different metals can be easily measured using a zero resistant ammeter ". This method can have specific application, e.g. to provide a signal indicating failure of a protective coating in a process vessel. Commercial probes are available for industrial monitoring. 

Impedance Some of the errors arising from the use of linear polarisation resistance led to interest and development in a.c. systems.An early development used a fixed a.c. frequency and a commercial instrument was produced in the UK. Inaccuracies still occurred, however, and were due to the electrode impedance which is fequency dependent. Electrode reactions have a capacitance component, in addition to resistance, resulting in a requirement to measure the impedance. However, the total impedance comprises values for the reaction, solution, diffusion and capacitance. Measurements at different frequency are more reliable, particularly where high solution resistances occur. Simplifications for industrial monitoring have been developed consisting of two measurements, i.e. at a high (10 kHz) and low frequency (0-1 Hz). The high-frequency measurement can identify the... 

One very important group of infrared instruments consists of spectrometers used for quantitative measurements either as part of a continuous industrial monitoring process or for environmental studies. These instruments are normally purpose-made, dedicated machines designed to run virtually automatically, and are normally intended only to measure a single compound or family of compounds. 

Based on industrial monitoring data Based on literature values (36)... 

Electrochemical sensors play a crucial role in environmental and industrial monitoring, as well as in medical and clinical analysis. The common feature of all electroanalytical sensors is that they rely on the detection of an electrical property (i.e., potential, resistance, current) so that they are normally classified according to the mode of measurement (i.e., potentiometric, conductometric, amperometric). A number of surveys have been published on this immense field. The reader may find the major part of the older and recent bibliography in the comprehensive reviews of Bakker et al. [109-111]. Pejcic and De Marco have presented an interesting survey... 

The polymer manufacturing industry monitors extrac-tables in their products for a variety of purposes. These include not only additives but also mineral oils and waxes as well as incompletely polymerised dimers and trimers that have a pronounced effect in the finished product. Myer et al. [390] have compared... 

Development of an industrial monitoring application for IMS requires extensive preparatory work, as well as optimal operational conditions for IMS, i.e. the nature of the reagent gas, calibration curves, evaluation of interferents, assessment of reliability. Analysis of mixtures with four or fewer components may be possible, but extension to more complex mixtures should be considered only in special cases, and generally would be unrealistic. Use of preseparators, such as GC columns, is the only known technical approach... 

Pulp and paper industries Monitoring of bleaching, yellowing Schmidt, 2000 ... 

Refrigeration Automotive and industrial, monitoring of refrigerants Gas composition analysis... 

The National Food Processors Association (NFPA) maintains a database on processed foods, or foods ready to eat. As described by Elkins et al. (1998), NFPA s Protective Screen Program was developed in 1960 and has been used to prevent illegal or unnecessary residues in processed foods. Four triazines have been included in the NFPA monitoring program atrazine, cyanazine, simazine, and ametryn. Through 1997, the NFPA database contained 6563 analyses for these four herbicides, and only 2 detects were found. One positive detect was observed for simazine in com at 0.04 ppm, and one atrazine detect was observed in wheat at 0.05 ppm. Both were well within the tolerance for these compounds in their respective commodities. This industry monitoring indicates that anticipated residues in processed foods are well below existing tolerances for both compounds. 

Source Global Insight - World Industry Monitor... 

The author recommends that future government and industry monitoring initiatives and field study programs have model validation as the primary goal and develop coordinated nested approaches of various levels of complexity. 

Food science is the study of the chemistry, microbiology, and processing of foods. Food technicians are responsible for testing foods for quality and acceptability in carefully controlled taste tests. Microbiologists in the food industry monitor the safety of food products. Food analysts work in laboratories to monitor the composition of foods and the presence of pesticides. Some food scientists create new food products or food ingredients, such as artificial sweeteners. 

The strength of correlation dies out as the number of sampling intervals between observations increases. In other words, as the sampling interval increases, the correlation between successive samples decreases. In some industrial monitoring systems, a large sampling interval is selected in order to reduce correlation. The penalty for this mode of operation is loss of information about the dynamic behavior of the process. Such policies for circumventing the effects of autocorrelation in data should be avoided. 

Highly technical units such as the 520th TAML and Tech Escort use Field Mini-CAMS. They are designed for field industry monitoring and require 8 hours of training. 

A Geiger counter is an instrument that detects ionizing radiation. Ions, produced by radiation passing through a tube filled with an ionizable gas, can conduct an electrical current between two electrodes. This current flow can be measured and is proportional to the level of radiation (Figure 10.11). Such devices, which were routinely used in laboratory and industrial monitoring, have been largely replaced by more sophisticated devices, often used in conjunction with a computer. 

U.S. Department of Agriculture conducts routine isotope analyses to ensure the purity of those products submitted for subsidy programs. Similarly, the honey industry monitors itself with the SIRA technique. 

The glass electrode used for measuring pH is one of the most successful examples of potentiometry in automated instruments. Modern glass electrodes are highly reliable they give selective, sensitive, and stable response to acidity over a very wide range of pH and have been widely applied in industrial monitoring and control. 

Industrial monitors used for control purposes can be implemented in different ways depending on 1) the corrosion interaction between the process stream analysed and the sensor, 2) on the degree of contamination of the medium by the sensor and 3) by the additives necessary to the operation of the sensor. 

Although the dielectric constant has no effect on the signal if dc conductivity is measured, the signal is the result of a collective property instead of depending on the concentration of a single component. Despite this fact, several conductometric industrial monitors have been constructed. If it can be ensured that the concentration of only one component changes... 

One IR spectroscopic system often used for industrial monitoring is the selective-wavelength spectrometer... 

Miscellaneous other uses of emission spectroscopy should be mentioned. The cement and glass industries use spectroscopic methods for quality control. The food and beverage industries monitor trace element concentrations during processing. Spectroscopy is used for forensic purposes, usually to help identify samples as to source or origin. Meteorite composition also has been studied by spectroscopic methods, as have lunar samples returned to earth by astronauts. Emission spectroscopy also has served as a research tool in chemistry and physics by providing composition information on research samples. 

Electrochemical noise This is a non-perturbation method and is defined as random low frequency low amplitude fluctuations either of the potential or current in a corroding system. Analysis of the corrosion potential noise can provide information relating to both the mechanism and kinetics of the corrosion occurring . The method has been applied to industrial monitoring in power generation plant, cooling water systems and reinforcement in concrete, and the method can provide information concerning localised corrosion and loss of passivity. 

This will become more and more of a problem for this industry. Monitoring and education are the keys here. 

Various analytical methods now employ amperometric measurements as part of their procedures. In particular, amperometric titrations have been widely used for the analysis of various substances in samples ranging from water to radioactive materials. Also, amperometric sensors, such as the dissolved oxygen probe and various amperometric biosensors, are widely used for clinical, environmental, and industrial monitoring. Furthermore, amperometric detectors have gained considerable use since the 1970s in high-performance liquid chromatographic determination of various substances and in flow injection analysis. 

These electrodes have nitrate-sensitive ion-exchange material incorporated into poly(vinyl chloride)-based membrane electrodes. Care is necessary to avoid contamination by the chloride from the saturated calomel reference electrode and a mercury/me-rcurous sulfate electrode is preferable as a reference electrode. Industrial monitors using nitrate ion-selective electrodes are commercially available. 

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