Magnetic devices

Polymer magnets, although common today, are a quite recent development. The first patent application was filed in France in 1955. Since that time, many ferromagnetic fillers have found their way to market. Plastics magnets do not match the performance of metal magnets but their properties are being systematically improved. 

Barium ferrites do not affect the mechanical properties of natural rubber and hence are useful in magnetic apphcations. Cure rates are increased considerably but ferrites may cause reversion problem. The magnetic properties increase almost linearly with the amount of ferrite added. 

A magnetic filler in the form of fiber was added to HDPE and injection molded test products were made. Anisotropic composites were manufactured to induce flow orientation of the fibers. The increased orientation contributed to the generation of a higher permeabihty magnet. The orientation can be affected by changing the die diameter. 

Magnetizable particles were used in the separation of biochemical compounds. Magnetizable particles of iron oxide are produced on different supports capable of absorbing various biological substances which are then removed from suspension by a magnetic field (see more about this application in Chapter 2). 

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Smoke damper A damper installed in a ductwork system designed to close in case of fite by means of a fusible link and electrical or magnetic device to stop the spread of smoke. 

Cathodic protection apparatuses are well proven, widely used devices and are not to be confused with magnetic devices gadgets ) or other similar but generally less than satisfactory items of capital equipment. Cathodic protection devices reverse the tendency of a metal to go into solution at the anode (corrosion) by the application of a counter-potential. This counter-potential or electromotive force (EMF) is provided either from a permanent external source such as a battery or rectifier or from the installation of a sacrificial anode. 

In practice, however, it is often the case that for small LP steam heating boiler systems with a very high percentage of CR, and in those regions of countries where soft water is supplied, no water softener is provided or deemed necessary. Instead there is merely a reliance on internal chemical treatments (or sometimes magnetic devices or other types of gadget ). A good rule of thumb is ... 

For more than 50 years, magnetic devices and other devices have been regularly tested and compared with other water treatment methods, notably chemicals. Although irrefutable, documented evidence of their beneficial effect in industrial water systems still seems sadly lacking, they have enjoyed a profitable share of the water treatment market. 

Magnetic devices A magnet(s) is fixed onto, or plumbed into a system, along the parallel axis of water flowing in a pipe. It is claimed that, with careful sizing and fitting, these devices inhibit the formation of scale. 

The arguments for and against the use of magnetic devices and similar technologies are periodically aired. These center around ... 

Whether magnetic devices and related technologies really do work under any or some limited circumstances is still debatable. It is clear, however, that, in general, the chemical-based water treatment companies remain extremely skeptical, although the market has perhaps... 

Whether electrostatic technology is superior to magnetic device technology is debatable. What is of interest is that, in a 1998 marketing and technical support documentation pack from a major electrostatic unit manufacturer, most of the information supplied related primarily to cooling water applications rather than boilers. The boiler data, such as there was, concerned only smaller, simple systems (e.g., HW boilers and steam ovens). 

NOTE The author has, on behalf of engineering personnel, occasionally conducted properly controlled, parallel trials of magnetic devices in hardworking industrial cooling systems. All trials were less than successful. 

NOTE EMS systems are legitimate technologies and should not be confused with magnetic devices proposed for pretreatment of MU water. 

In the experiment, target 1 (semiconductor ZnO film) was exposed to a beam of metal particles for a specified time interval by activating a shutter 3 (controlled by a magnetic device) installed in front of a diaphragm 4, with magnetic field on and magnetic field off. The rate of variation of an electric conductivity was measured. At small surface coverages, this rate is strictly directly proportional to the number of metal atoms incident on the film surface, i.e., (da/dt) /, where is the atomic beam intensity. The shorter was the time of exposition and... 

Iron Oxide Fe304 FeO(OH) Magnetite Ferritin Bacteria-chitons teeth Widespread Magnetic device Iron store... 

R. Kindervater, W. Kiinnecke, and R.D. Schimid, Exchangeable immobilized enzyme reactor for enzyme inhibition tests in flow-injection analysis using a magnetic device. Determination of pesticides in drinking water. Anal. Chim. Acta 234, 113-117 (1990). 

The properties of modern electronic, optoelectronic, photonic, and magnetic devices provide another story of great science that has affected most of humankind. Electronic devices require special materials materials that emit light when struck by a beam of electrons for use in television screens and computer monitors, materials to make the semiconductors that are the heart of electronic and microelectronic circuits, and materials that are used in magnetic memory storage devices for computers. 

FIGURE 10.2 A schematic drawing of the sensor (tip/cantilever/optical/magnetic device) movement over a substrate in x/y/z direction with nanometer sensitivity controlled by piezomotor at the solid-gas or solid-liquid interface. 

The opening of the test pipe has been designed and tested to ensure fully developed turbulent flow in the test section. Hence, the inlet length of the pipe to the first pressure gap amounts to 220 x d. The device has been carfully tested and calibrated with water, which complies with the Newtonian theory of fluids for smooth pipes. Measurements are taken after stabilization occurs and then a magnetic device in the form of a swinging arm turns the outlet tube to the collecting vessel and at this moment a stop-watch is... 

Physical devices (catalytic devices) for the nonchemical treatment of water, and more specifically for scale prevention, have been commercially available for 25 years or so. Physical devices include electronic, catalytic, and magnetic water treatment, etc. More widely known are various types of magnetic devices. There are also other more recent alternative technologies to chemical treatments available in the marketplace. Some of these technologies are summarized here ... 

Two examples of magnetic devices are discussed in the following sections. 

Cooling system operators are required to install a bleed-off in the recirculating line between the pump and the magnetic device to remove suspended minerals and dissolved solids from the system, and are further required to install a constant bleed-off in the cooling system sump or lowest point to keep mud and loosened scale from accumulating in the system. 

It is useful to be able to compare the relative costs of a typical magnetic device system with a water treatment chemical program (scale, corrosion, and dispersion of sludges only). Although selling prices may vary considerably across the competitive market spectrum and will also tend to rise over the years, a very basic exercise, as discussed below and shown in Table 3.3, will serve to provide some comparison. 

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