Special devices

Attempts have been made to include a variety of sample treatments as on-line devices into flow systems. Separation of a gaseous component and re-introduction into a liquid flow system has been described by Grasshoff and Hansen (1979) for the determination of total carbon dioxide and by Ehrhardt (1969) for the determination of total dissolved organic carbon. 

A dialyser introduced by Skalar in the flow-analysis of sulphate, permits an exchange of sulphate from the sample into a reagent flow through a membrane. Contact with sample components other than sulphate are thus avoided and sulphate enters the analytical flow at a high dilution. 

As previously described, the determinatioii of nitrate requires reduction to convert nitrate into nitrite. Reductors which can be used in manual as well as flow analyses are described in Section 10.2.9.5. A three-way valve allows bypassing of the reduction. 

Blocking of a tube (in particular capillary tubes) by particles is one of the major malfunctions of flow systems. As a consequence the system pressure increases causing variations in pump and flow rates and finally a blow-off of tube connections. 

A valuable device to monitor the system flow, Le., detect system blockages or tube breaking, has been introduced by H. Johannsen (Institute for Marine Research, Kiel). Hie device (Fig. 10-23) monitors the pressure of the flow system at the beginning of the tubing system. 

In principle the combination of fibre optics and photodiode array spectrometers shows great advantages in photokinetics. Fibre optic technology allows a wide variation of such set-ups. In the 1960s one tried to achieve a versatile spectrometer by combining modules such as light source, monochromator, cell compartment, and detector on an optical bench. This arrangement of the different components allowed the measurement of absorbance, fluorescence, and reflectance. The same can be achieved nowadays by the use of a so-called simultaneous spectrometer module, schematically presented in Fig. 4.11. 

A ceramic block contains a grating and the diode array. A fibre optic guides the measurement light to the sample, the second arm of the bifurcated fibre optic observes the sample and transfers the information to the entrance slit of the spectrometer. 

This modular apparatus allows even very special applications. As a further example a combined measurement and irradiation device can be set up where the sample is placed in a Dewar and kept at low temperature. Fast shutters, a beam splitter, and a repositioning device for sample and reference allow the uninterrupted examination of photochemical reactions under specific conditions (see Fig. 4.12) [54]. 

The application of photodiode arrays in photokinetics results in many advantages, but they require some optical understanding to obtain photometri-cly correct data. For this reason their principles are explained in a later chapter in more detml. 

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The percentage share of the inserts made austenite steel in the martensite structure is refered to the visual field of the probe in the given location. Every probe after performance is given a characteristics, in which the visual field is given, determined using special devices defining the visual field at different distances from the tested object. 

The above simple process cannot be applied to the preparation of the homo-logues a higher temperature is requir (di-n-amyl ether, for example, boils at 169°) and, under these conditions, alkene formation predominates, leading ultimately to carbonisation and the production of sulphur dioxide. If, however, the water is largely removed by means of a special device (see Fig. Ill, 57,1) as soon as it is formed, good 300 of ethers may be obtained from primary alcohols, for example ... 

Free-Electron Lasers. The free-electron laser (EEL) directly converts the kinetic energy of a relativistic electron beam into light (45,46). Relativistic electron beams have velocities that approach the speed of light. The active medium is a beam of free electrons. The EEL, a specialized device having probably limited appHcations, is a novel type of laser with high tunabiHty and potentially high power and efficiency. 

The AeroSizer, manufactured by Amherst Process Instmments Inc. (Hadley, Massachusetts), is equipped with a special device called the AeroDisperser for ensuring efficient dispersal of the powders to be inspected. The disperser and the measurement instmment are shown schematically in Figure 13. The aerosol particles to be characterized are sucked into the inspection zone which operates at a partial vacuum. As the air leaves the nozzle at near sonic velocities, the particles in the stream are accelerated across an inspection zone where they cross two laser beams. The time of flight between the two laser beams is used to deduce the size of the particles. The instmment is caUbrated with latex particles of known size. A stream of clean air confines the aerosol stream to the measurement zone. This technique is known as hydrodynamic focusing. A computer correlation estabUshes which peak in the second laser inspection matches the initiation of action from the first laser beam. The equipment can measure particles at a rate of 10,000/s. The output from the AeroSizer can either be displayed as a number count or a volume percentage count. 

Regardless of the method of evaluating the solids mixture, the sampling procedure is vital. Often a sampling thief, or other special device, is used to remove samples from the mixture without excessive disturbance of the batch. If an easier method of sampling is obvious and will bring less contamination to the batch, it should be used. 

Nature of a Fog. Fog, like smoke, is a colloid. Once a fog is formed, it is very difficult to knock down. It will go right through packed columns, mist eliminators, or other such devices. Special devices are required to overcome a fog, such as an electric precipitator with charged plates. This can overcome the zeta potential of the charged particles and make them coalesce. 

Instead of a sorbent contained in a precolumn, discs can also be used with a special device (38, 39) which enables the number of discs to be changed easily, although this technique is currently limited to the kind of discs that are commercially available. 

Special devices have been used to study erosion-corrosion by boiler water moving at high velocity, and an example is the method used by Wagner, Decker and Marsh . 

Single plates are usually cured in special devices (curing ovens or curing chambers, cf., e.g., [25] ) that control humidity as well as temperature. In continuous plate production, the drying of the pasted ribbon is correspondingly controlled. Furthermore, in continuous manufacture final curing can occur after the plates are separated and inserted into the containers. 

In the case of a continuous monitoring a special device must generally be used. This apparatus is characteristic of a method which is used and is described further (continuous monitoring). 

Many attachments and special devices have been developed to extend and implement the applicability of the OM. One of these is a controlled atmosphere microscope dry-box which offers reproducible environmental control for applications involving toxic, air, or moisture sensitive ingredients, typical of many energetic materials (Ref 33)... 

In separate-loading ammo, obturation is achieved by a special device, called an Obturator... 

Turbidity, due to solid particles in suspension, is a parameter generally neglected. However, under water scarcity, it is very important to be controlled because it may restrict the use of water for irrigation. Solid particles may clog the water distribution systems as drippers or sprinklers. They may also affect the soil permeability. This is why in different countries in the Mediterranean region special devices for the removal of sediments especially are used when marginal waters are only available for irrigation. 

If the acting force causes a roll deflection which exceeds a certain lateral displacement of the roll the thickness gradient across the calendered product might be beyond the required value which means that a calender shall include some special devices to compensate this roll deflection. Some well-known devices are... 

Fuel-cell-based power plants (or electrochemical generators, the rather appropriate Russian term) have several constituent parts (1) the fuel cell battery or stack itself (2) vessels for the reactants (hydrogen or methanol oxygen when needed) (3) special devices controlling the supply of reactants and withdrawal of the reaction products according to their consumption and formation in the electrochemical reactions ... 

The flow pattern of fluids in gas-liquid-solid (catalyst) reactors is often far from ideal. Special care must be taken to avoid by-passing of the catalyst particles near the reactor walls, where the packing density of the catalyst pellets is lower than in the centre of the bed. By-passing becomes negligible if the ratio of reactor to particles diameter is larger than 10 a ratio of 20 is recommended. Flow maldistributions might be serious in the case of shallow beds. Special devices must be used to equalize the velocity over the cross-section of the reactor before reactants are introduced onto the catalyst bed. 

Class II Special Devices for which general control alone is insufficient to provide... 

Collaboration with Beamline Staff. If the beamline staff accepts scientific collaboration with the user, the beamline scientists will actively participate in the experiment and the engineers will help with the adaption of special devices. Such active cooperation should be awarded co-authoring the resulting papers, in particular if the colleagues have participated in the data evaluation and in the discussion of the manuscripts. 

Test facilities are also used to investigate specific attrition phenomena of individual processes. Up to now only a few investigations have been carried out in full-scale equipment. Most results were obtained from very special devices which makes it difficult to compare the results of various research groups and to draw general conclusions. Despite of these difficulties, the specific attrition phenomena in fluidized beds and pneumatic conveying lines will be summarized in the Secs. 5 and 6, respectively. It will... 

By themselves, valves cannot control a process. Manual valves require an operator to position them to control a process variable. Valves that must be operated remotely and automatically require special devices to move them. These devices are called actuators. Actuators may be pneumatic, hydraulic, or electric solenoids or motors. 

The description of special device for TV-computer photometry is given in Suppl.3. 

Reliable deep-water sampling is a special and demanding art. It usually has to be done from the research vessel. Special devices and techniques have been developed to provide reliable samples. 

The use of a special device that allows filtration under nitrogen, the direct introduction of sample into containers for storage during filtration and, the use of these containers as analysis cells are all improvements that minimise external sample contamination and improve between-sample reproducibility. 

Automation CL measurements can be performed very rapidly and with minimal human participation if the flow system is carefully designed. Several reagents can be added to the sample if multiple flow lines are used and at predetermined times to fulfill the best condition for maximum CL sensitivity. Introduction of special devices into the flow line, which allow procedures otherwise time-consuming such as solvent extraction or ion exchange, improve substantially the sensitivity and selectivity of the technique. 

If the foregoing created the impression that the electric and magnetic vectors of a propagating electromagnetic field are confined to vibrate in fixed planes, that was unintentional. A field like that would be plane polarized and to create that requires a special device known as a polarizer. Ordinary unpolarized light consists of an array of plane waves that are randomly oriented with respect to a plane perpendicular to the directions of propagation. 

The measurement is always relative, that is, in 14C measurements the amount of 14C is always related to that of 13C or 12C. The more abundant isotope is detected by a Faraday detector while the less abundant isotope is detected by a specialized device... 

However, infusion also has its limitations. Skilled labor is required, and the setup must be monitored over the entire period of infusion. Larger animals must be restrained, while there are special devices that make this requirement unnecessary for smaller animals. Restraint and protracted manipulation are very stressful on animals. Over a period of time, one must regularly demonstrate patency of a device, that is,... 

A special device was used to collect artificially resuspended sediment. In this device, the sediment was placed in a tube with overlying water. An oscillating grid placed in the water above the sediment caused a steady state resuspension equilibrium, under the same conditions as typically generated by winds and currents in the lagoon. This overlying water was then filtered, and the resuspended material analysed. 

These amines used as inhibitors show negative side effects (disturbances) when used for larger plants. They can be regarded as pollutants by themselves, and can disturb special devices in the plants, especially, when used on a larger scale, filters like electrostatic precipitators. Therefore, we have improved the inhibition method by the use of much safer inorganic compounds as inhibitors, such as. 

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