Physical contact

Two basic methods are used for the appHcation of protective coatings to metal containers, ie, roUer coating and spraying. RoUer coating is used if physical contact is possible, eg, coating of metal in sheet and coil form. Spraying techniques are used if physical contact is not possible, eg, to coat the inside surface of two-piece drawn and ironed can bodies (see Coating processes). 

Induction furnaces utilize the phenomena of electromagnetic induction to produce an electric current in the load or workpiece. This current is a result of a varying magnetic field created by an alternating current in a cod that typically surrounds the workpiece. Power to heat the load results from the passage of the electric current through the resistance of the load. Physical contact between the electric system and the material to be heated is not essential and is usually avoided. Nonconducting materials cannot be heated directiy by induction fields. 

The compact disk player has become a very widespread consumer product for audio reproduction. The information is stored along tracks on the disk in the form of spots of varying reflectivity. The laser beam is focused on a track on the surface of the disk, which is rotated under the beam. The information is recovered by detecting the variations in the reflected light. The compact disk offers very high fideHty because there is no physical contact with the disk. This appHcation has usually employed a semiconductor laser source operating at a wavelength of around 780 nm. Tens of millions of such compact disk players are produced worldwide every year. 

In case of physical contact with sulfuric acid, immediately flush eyes or skin with plenty of water for at least 15 min while removing contaminated clothing and shoes. Call a physician. Wash clothing before reuse and destroy contaminated shoes. 

Droplet size, particularly at high velocities, is controlled primarily by the relative velocity between liquid and air and in part by fuel viscosity and density (7). Surface tension has a minor effect. Minimum droplet size is achieved when the nozzle is designed to provide maximum physical contact between air and fuel. Hence primary air is introduced within the nozzle to provide both swid and shearing forces. Vaporization time is characteristically related to the square of droplet diameter and is inversely proportional to pressure drop across the atomizer (7). 

Conduction is the transfer of heat from one part of a body to another part of the same body, or from one body to another in physical contact with it, without appreciable displacement of the particles of the body. 

Rotaiy diyers have been classified as direct, indirect-direct, indirect, and special types. The terms refer to the method of heat transfer, being direct wnen heat is added to or removed from the sohds by direct exchange between flowing gas and solids and being indirect when the heating medium is separated from physical contact with the solids by a metal wall or tube. 

Galvanic corrosion is location specific in the sense that it occurs at a bimetallic couple (Fig. 16.2). It is metal specific in the sense that, typically, corrosion affects the metal that has less resistance in the environment to which the couple is exposed. Hence, in principle, we would anticipate galvanic corrosion of relatively reactive metals wherever they are in physical contact with relatively noble metals in a sufficiently aggressive, common environment. Experience has shown, however, that all such couples do not necessarily result in unsatisfactory service. This is because of the interplay of various critical factors that influence galvanic corrosion. These critical factors are discussed in the next section. 

Mining. A solid-state semiconductor device has no physical contacts to make or break the current. There is thus no arc formation during switching of these... 

Toxicity The ability of a substance to produce a harmful effect on an organism by physical contact, ingestion, or inhalation. 

Protection of monitoring and sampling instruments by covering them with plastic or plastic bags (openings can be made in the bags for sample ports and sensors that are required to physically contact worksite materials). 

The more enclosed a process is, the easier it is to keep a low concentration in the workroom. It is usually necessary for the workers or for some equipment to have physical contact with the process, w hich could make it difficult to use complete enclosures. If it is possible to enclose the contaminant source and the tool, a total enclosure is recommended, especially if the workers only need to access the process during pauses in operation. Total enclosures may also be necessary for processes that generate highly toxic contaminants. Where total enclosures are not practicable, partial enclosures may be used. F xterior hoods are the least effective exhaust hood. 

Considerable care must be taken at all times when using potassium cyanide to avoid any form of physical contact and chemical antidotes must be kept permanently and easily available. 

Repellency appears to be associated with the highly pungent odor of the material since physical contact is unnecessary. The oily repellent is stable to heat and is not phytotoxic to the seedlings when proper aeration is provided. 

Catalytic activity is a result of physical contact the reaction ceases when particles no longer present a salt-additive interface. 

When an antineoplastic drag is administered orally, the nurse must handle the drag safely. Gloves are considered acceptable if physical contact with the tablet or capsule is necessary. 

The atmosphere, as a single body of gas, is in physical contact with the entire surface of the Earth. It extends upward toward space, with... 

Physical contact between chemical and electrical parts of the cell... 

Propagated outbreaks of infection relate to the direct transmission of an infective agent from a diseased individual to a healthy, susceptible one. Mechanisms of such transmission were described in Chapter 4 and include inhalation of infective aerosols (measles, mumps, diphtheria), direct physical contact (syphilis, herpes virus) and, where sanitation standards are poor, through the introduction of infected faecal material into drinking water (cholera, typhoid). The ease oftransmission, and hence the rate of onset of an epidemic (Fig. 16.3) relates not only to the susceptibility status, and general state of health of the individuals but also to the virulence properties of the organism, the route oftransmission, the duration of the infective period associated with the disease. 

Exposure to trichloroethylene can occur via the inhalation, oral, and dermal routes in people living in areas surrounding hazardous waste sites if evaporation occurs from contaminated soils or spill sites, or if contaminated water is ingested or used in bathing. Individuals who work in the vicinity of industries that use this substance may breathe trichloroethylene vapors or come into physical contact with spilled trichloroethylene. The group with the greatest likelihood for substantial exposure to trichloroethylene consists of those exposed to trichloroethylene in the workplace. 

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