Electrical devices

PEN is used in manufacturing electrochemical lithium ion batteries because it is dimensionally stable and highly resilient [54], It could replace polyethylenimine, which is currently used at unusually high temperatures to cure special inks. PEN is also useful in membrane touch switches (MTSs) where the circuit would be exposed to a high temperature, such as the domes for switches and seat sensors in automobiles. PEN is also particularly suited to a wide range of flexible heaters and low- to intermediate-voltage heaters, such as waterbed heaters and battery heaters. 

---

The SI unit for magnetic field strength is the tesla (T) named after Nikola Tesla a contemporary of Thomas Edison and who like Edison was an inventor of electrical devices... 

W/m -nm at 340 nm ( ) represents sunshine carbon arc with Corex and (-) represents daylight. Courtesy of Adas Electric Devices Co. 

Some amino resins are used as additives to modify the properties of other materials. For example, a small amount of amino resin added to textile fabric imparts the familiar wash-and-wear quaUties to shirts and dresses. Automobile tires are strengthened by amino resins which improve the adhesion of mbber to tire cord (qv). A racing sailboat may have a better chance to win because the sails of Dacron polyester have been treated with an amino resin (1). Amino resins can improve the strength of paper even when it is wet. Molding compounds based on amino resins are used for parts of electrical devices, botde and jar caps, molded plastic dinnerware, and buttons. 

One of the first important uses of sihcon carbide was as an abrasive (see Abrasives). Additional markets in refractories, electrical devices, and metallurgy have since been developed. In 1988, the sihcon carbide market was estimated at 55% metallurgical, 43% abrasive, and 2% for refractories and... 

These include the use of coalescers, separating membranes, and electrical devices and the addition of emulsion-breakiug reagents. These last are used for treating permanent enmlsions and whl not be discussed here. 

In order to develop measures for removal of debris from the waste matrix, the general types of debris anticipated need to be identified. A composite list, based on debris found at 29 Superfund sites, was developed. The list includes cloth, glass, ferrous materials, nonferrous materials, metal objects, construction debris, electrical devices, wood existing in a number of different forms, rubber, plastic, paper, etc., as presented in Table 11. Similar types of debris would be expected at RCRA sites. 

Airflow rate controller Any mechanical, pneumatic, or electrical device that controls the air flow rare into Or out of a space by increasing or decreasing the flow resistance. See Dampers and Valve. 

Electric control An electrical device that controls some mechanical function, such as a damper control. 

Electrical properties Relating to the resistance, electrical capacity, and insulating characteristics of a conductor or electrical device. 

Pulse The regular beating of the blood in the main blood vessel, a pulse of electricity, the vibrating of a mechanical or electrical device. 

Thermohydrograph A mechanical or electrical device that records simultaneously the relative humidity and temperature of the air throughout the day. 

Fig. 3.8. The time periods over which significant developments are reported in the literature for the various electromagnetic and optical devices are shown. As for the electrical devices, the development periods are 10 yr or longer.

Hermetically sealed electrical devices must be verified by a testing laboratory to meet mechanical abuse and to withstand aging and exposure to expected chemicals. Devices potted with common silicones and similar materials by an end user or even a manufacturer, without testing, and devices merely provided with O-rings seldom meet acceptable criteria. Normally, hermetically sealed devices must be sealed through metal-to-metal or glass-to-metal fusion. Many electrical relays, switches, and sensors are available as hermetically sealed devices for common oil and gas producing facility applications. Hermetically sealed devices are often desirable to protect electrical contacts from exposure to salt air and other contaminants. 

LIMITATIONS ON INSTALLATION OF ELECTRICAL DEVICES IN HAZARDOUS AREAS... 

At present batteries worth more than 30 billion USD are produced every year and the demand is still increasing rapidly as more and more mobile electronic end electric devices ranging from mobile phones to electric vehicles are entering into our life. The various materials required to manufacture these batteries are mostly supplied by the chemical industry. Ten thousands of chemists, physicists and material scientists are focusing on the development of new materials for energy storage and conversion. As the performance of the battery system is in many cases a key issue deciding the market success of a cordless product there is in fact a kind of worldwide race for advanced batteries. 

One of the most stringent and most widely accepted test is UL 94 that concerns electrical devices. This test, which involves burning a specimen, is the one used for most flame-retardant plastics. In this test the best rating is UL 94 V-0, which identifies a flame with a duration of 0 to 5 s, an afterglow of 0 to 25 s, and the presence of no flaming drips to ignite a sample of dry, absorbent cotton located below the specimen. Tlie ratings go from V-0, V-l, V-2, and V-5 to HB, based on specific specimen thicknesses. 

Capacitor There are several applications for plastics in electrical devices that use the intrinsic characteristics of the plastics for the effect on the electrical circuit. The most obvious of these is the use of plastics particularly in the form of thin films as the dielectric in capacitors. TP polyester films such as Mylar are especially useful for this type of application because of the high dielectric strength in conjunction with a good dielectric constant. 

Sulfur hexafluoride is a colorless, odorless, nontoxic, unreactive gas. It is prepared commercially by reacting sulfur with excess fluorine. Because of its unusual stability, sulfur hexafluoride is used as an insulating gas for high-voltage electrical devices. 

The relatively large band gaps of silicon and germanium limit their usefulness in electrical devices. Fortunately, adding tiny amounts of other elements that have different numbers of valence electrons alters the conductive properties of these solid elements. When a specific impurity is added deliberately to a pure substance, the resulting material is said to be doped. A doped semiconductor has almost the same band stmeture as the pure material, but it has different electron nonulations in its bands. 

Chromium makes up just 0.012% of the Earth s crust, yet it is an important industrial metal. The main use of chromium is in metal alloys. Stainless steel, for example, contains as much as 20% chromium. Nichrome, a 60 40 alloy of nickel and chromium, is used to make heat-radiating wires in electrical devices such as toasters and hair dryers. Another important application of chromium metal is as a protective and decorative coating for the surface of metal objects, as described in Chapter 19. 

---