Tracer systems

Are ambient sensing valves used to turn off steam tracer systems ... 

The electric heat tracer systems require good temperature control. A self-regulating system is shown in Figure 10-169. The manufacturers should he consulted to prepare proper temperature control systems. 

As indicated above, frequently the amount of material involved in a radiochemical procedure is quite small. To obviate some of the difficulties associated with this, a weighable amount ( mg) of inactive material, the carrier, is added to the procedure at an early stage. It is essential that this carrier and the radionuclide (tracer) be in the same chemical form. This is achieved usually by subjecting the carrier + tracer system to one or more redox cycles prior to initiating any chemical separations to ensure that the carrier and tracers are in the same oxidation state. 

P.-F. Cevey and U. von Stockar, A tracer system based on a photochromic dye and on fiber optics for measuring axial dispersion of organic liquids in pilot-scale packed columns, Chem. Eng. J., 31, 7-13 (1985). 

The methods of continuous isotopic analysis of the product or of successive product fractions have been applied to tracer systems, where k/k —l l, by Ropp, Weinberger, and Neville,51 Downes,51 and Schmitt, Myerson, and Daniels.55 The expressions for (k/k —l) can be developed conveniently from Eqs. V.22and V.23. Consider an experiment in which the reaction is allowed to proceed to an extent ft of completion. The product formed between ft and /, of completion is isolated for isotopic assay. From Eq. V.23 one obtains... 

In remote areas, CMB methods are not applicable due to the mixed influence of numberless sources. FA generally tends to uncover obviously influencing sources such as maritime, crustal, and mixed anthropogenic ones (Heidam 1981). More promising for such regions is the use of enrichment factors (Zoller et al. 1974) and of tracer systems (Rahn 1985). The enrich-... 

With the use of a seven-element tracer system, Lowenthal and Rahn (1985) came to the conclusion that roughly 70% of the tracer elements observed in Alaska came from the former Soviet Union, 25% from Europe, and the remainder from North America. Support for the tracer sets used for Central Europe has been found by Borbely-Kiss etal. (1988). 

The methods of continuous isotopic analysis of the product or of successive product fractions have been applied to tracer systems, where by Ropp, Weinberger, and Neville, Downes, ... 

Figure 8.12 Schematic diagrams of a Rh target side-window tube (ARTAX system) and a modem handheld transmission target design (TRACER system). (Courtesy of Roald Tagle, BRUKER NANO GmbH, Berlin, Germany. 2013 Bmker, Inc. Used with permission.)...

Recently a fluorescent tracer system was proposed for automatic identification and sorting of waste plastics [252]. The system is based on the following three elements the use of selected tracers in the polymer, a high speed system for identification of the tracers, a process for automatically separating the plastics identified. 

It would appear that the use of laser-aided polymer waste sorting [137] (eventually in combination with LIBS) and fluorescent tracer systems (cfr. Chp. 1.4.2) [152] are technologically the most attractive, with the latter technology more geared towards the identification of polymers than additives. 

The use of tracers enables efficient and reliable measurements of oil, gas and water flow in industrial process units and pipe line systems under production conditions thus fundamentally being non-destructive testing methods. Typical problems which can be efficiently assessed by tracer studies include ... 

A tracer is a minute amount of matter similar to the bulk material which is added to a flow system without affecting the bulk flow and the concentration of which is measurable. Obtaining information of the tracer flow by measurements provides information about bulk flow properties. 

Flow measurements using tracers are performed in all piping systems carrying oil, gas or water including separators, compressors, injector systems, and flares. Calibration of elsewhere difficult accessible flow meters is regularly performed by the tracer methods, which are based on international standards. Tracer flow measurements are also well suited for special purposes... 

In situ control and calibration of flare and other gas metering systems is performed by gaseous tracers using the transit time method without affecting the normal production. Details about methodology are given in / /. 

The technique just described requires the porous medium to be sealed in a cell, so It cannot be used with pellets of irregular shape or granular material. For such materials an alternative technique Introduced by Eberly [64] is attractive. In Eberly s method the porous pellets or granules are packed into a tube through which the carrier gas flows steadily. A sharp pulse of tracer gas is then injected at the entry to the tube, and Its transit time through the tube and spreading at the exit are observed. A "chromatographic" system of this sort is very attractive to the experimenter,... 

A rapid increase in diffusivity in the saturation region is therefore to be expected, as illustrated in Figure 7 (17). Although the corrected diffusivity (Dq) is, in principle, concentration dependent, the concentration dependence of this quantity is generally much weaker than that of the thermodynamic correction factor d ap d a q). The assumption of a constant corrected diffusivity is therefore an acceptable approximation for many systems. More detailed analysis shows that the corrected diffusivity is closely related to the self-diffusivity or tracer diffusivity, and at low sorbate concentrations these quantities become identical. 

Radiometric detection technology offers high sensitivity and specificity for many appUcations in scientific research. The radioactive emission of the labeled compound is easily detected and does not suffer from interference from endogenous radioactivity in the sample. Because of this unique property, labeled compounds can be used as tracers to study the localization, movement, or transformation of molecules in complex experimental systems. 

The radioactive isotopes available for use as precursors for radioactive tracer manufacturing include barium [ C]-carbonate [1882-53-7], tritium gas, p2p] phosphoric acid or pP]-phosphoric acid [15364-02-0], p S]-sulfuric acid [13770-01 -9], and sodium [ I]-iodide [24359-64-6]. It is from these chemical forms that the corresponding radioactive tracer chemicals are synthesized. [ C]-Carbon dioxide, [ C]-benzene, and [ C]-methyl iodide require vacuum-line handling in weU-ventilated fume hoods. Tritium gas, pH]-methyl iodide, sodium borotritide, and [ I]-iodine, which are the most difficult forms of these isotopes to contain, must be handled in specialized closed systems. Sodium p S]-sulfate and sodium [ I]-iodide must be handled similarly in closed systems to avoid the Uberation of volatile p S]-sulfur oxides and [ I]-iodine. Adequate shielding must be provided when handling P P]-phosphoric acid to minimize exposure to external radiation. 

The methods for detection and quantitation of radiolabeled tracers are deterrnined by the type of emission, ie, y-, or x-rays, the tracer affords the energy of the emission and the efficiency of the system by which it is measured. Detection of radioactivity can be achieved in all cases using the Geiger counter. However, in the case of the radionucHdes that emit low energy betas such as H, large amounts of isotopes are required for detection and accurate quantitation of a signal. This is in most cases undesirable and impractical. Thus, more sensitive and reproducible methods of detection and quantitation have been developed. 

If the source fingerprints, for each of n sources are known and the number of sources is less than or equal to the number of measured species (n < m), an estimate for the solution to the system of equations (3) can be obtained. If m > n, then the set of equations is overdetermined, and least-squares or linear programming techniques are used to solve for L. This is the basis of the chemical mass balance (CMB) method (20,21). If each source emits a particular species unique to it, then a very simple tracer technique can be used (5). Examples of commonly used tracers are lead and bromine from mobile sources, nickel from fuel oil, and sodium from sea salt. The condition that each source have a unique tracer species is not often met in practice. 

B. J. Ehrlich and S. E. Spencer, Development of an Automated Mustard S tack Monitor, Edgewood Arsenal Report No. ED-CR-76084, Tracer, Inc., June 1976. L. Schwart2 and co-workers. Evaluation of Ml 5/Ml 8 Enyme Detector Ticket System with Eow Concentration of GB, Edgewood Arsenal Report No. 

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