Connections Connectors

Connections Connectors and manifolds should not be for common use. For example, sharing connectors in a water supply, premix, or raw material supply tanks may be a source of cross-contamination [6],... 

FIGURE 14.5 Schematic diagram of SPME-IMS system (1) needle guide (2) septum (3) T-connection connector (4) modified SRI GC liner (5) nut with punched septum (6) transfer line/desorber (7) PEEK union (8) IMS (9) power lead and clamps (10) thermocouple. FAIMS, field asymmetric IMS. PEEK, polyether ether ketone. (From Liu et al., A new thermal desorption solid-phase microextraction system for hand-held ion mobility spectrometry, Anal. Chim. Acta 2006, 559, 159-165. With permission.)... 

Figure 12.22. Electrical connections (a) washer (b) nut (c) pillar terminal (d) socket (e) wrapped joint (f) tag (g) bullet connector (h) quick-connect connector...

One of the primary tasks in connection with the use of AE method is to identify defects by the AE parameters. For identification of nature of the destruction centre in the polymeric composites it is necessary to consider the peculiarities of their heterogeneous structure, that is presence of at least two different components (filler and connector), and also boundary transitional layers. 

Receiver adapters or connectors. Various forms of receiver adapters are shown in Figs. 11, 56, 26-29. The simplest form. Fig. 11, 56, 26, carries a glass hook for securing it to the condenser by means of a rubber band from the side tube to the hook an improved form, incorporating two ground glass joints is shown in Fig. 11, 56, 27. A useful adapter is illustrated in Fig. 11, 56, 28 when employed at atmospheric pressure, a drying tube may be attached to the side tube, if desired in a distillation under reduced pressure, the side tube is connected to the pump. Fig. 11, 56, 29 depicts a receiver adapter with an additional socket connection. 

Union Connectors. CoUar and cone-type connectors (Figs. 26a and b) are nearly always used to connect smaU bore tubes at pressures up to about 400 MPa (140). The included angle of the end of the tube is 55—57° and that of the seat 60—61° so that when the gland nut is tightened into the connector a metal-to-metal seal is formed along a narrow band of contact between the end of the tube and the connector. Union connectors for smaU bore tubes at pressures of 500 MPa and above usuaUy employ lens rings. 

In addition, most devices provide operator control of settings for temperature and/or response slope, isopotential point, zero or standardization, and function (pH, mV, or monovalent—bivalent cation—anion). Microprocessors are incorporated in advanced-design meters to faciHtate caHbration, calculation of measurement parameters, and automatic temperature compensation. Furthermore, pH meters are provided with output connectors for continuous readout via a strip-chart recorder and often with binary-coded decimal output for computer interconnections or connection to a printer. Although the accuracy of the measurement is not increased by the use of a recorder, the readabiHty of the displayed pH (on analogue models) can be expanded, and recording provides a permanent record and also information on response and equiHbrium times during measurement (5). 

Copper and nickel can be alloyed with zinc to form nickel silvers. Nickel silvers are ductile, easily formed and machined, have good corrosion resistance, can be worked to provide a range of mechanical properties, and have an attractive white color. These alloys are used for ornamental purposes, as sHverplated and uncoated tableware and flatware in the electrical iadustry as contacts, connections, and springs and as many formed and machined parts (see Electrical connectors). 

In addition to the circuit breaker, there have been a number of other SMA appHcations for various functions in electric power generation (qv), distribution, and transmission systems. One such device is a thermal indicator that provides a signal visible from the ground of a hot junction or connector in a distribution yard. Such hot spots occur as a result of the loosening of bus bar connectors owing to cycHc temperature as the electric load varies. In addition to the use of SMA flags as a hot-spot indicators, actuators that automatically maintain the contact force in a bus bar connection have been demonstrated. Based on a BeUeviHe washer fabricated from a Cu—Al—Ni SMA trained to exhibit two-way memory, these washers, when heated by a hot joint, increase their force output and correct the condition. A 30 mm diameter washer 3 mm thick can produce a force of over 4000 N. Similar in purpose... 

Electrical Connections. Electric current is brought from the transformers by air-cooled copper busbars and close to the electrode by water-cooled bus tubes and flexible cables, connecting to water-cooled copper contact plates at the electrode. The plates are held against the electrode by hydraulic pressure. The connectors are as short and as balanced as possible to allow cancelling of magnetic fields associated with individual conductors. 

Electronic Connectors. The complexity and size of many electronic systems necessitate constmction from relatively small building blocks which ate then assembled with connectors. An electronic connector is a separable electrical connector used in telecommunications apparatus, computers, and in signal transmission and current transmission <5 A. Separable connectors ate favored over permanent or hard-wired connections because the former facilitate the manufacture of electronic systems also, connectors permit assemblies to be easily demounted and reconnected when inspection, replacement, or addition of new parts is called for. 

Electronic connectors may connect internally or externally. Internal connections may be between a component and a printed circuit board or wire (Fig. la) a printed circuit board and a wire or another printed circuit board which is in a chassis (Fig. lb) and between chassis in the same cabinet (Fig. 

A popular connection system consists of square metal pins, usually 0.064 cm (0.025 in.) in size, that are pressed into holes drilled in a printed circuit board. The holes are copper (qv) plated on the insides and interconnect conductors on the top and bottom faces of the board. Multilayer boards have interior circuits that may also be interconnected in this way. The pias have either a soHd shank or a deformable (compHant) cross section where the pias joia the board (Fig. 2). Separable connectors or soldedess wraps (Fig. 3) engage the ends of the pias. One end of the pia can be the contact and spring of a separable connector. 

Another design which provides unusually low mating forces employs bundles of wires in both halves of the connector that intermesh, like two hair bmshes, when the parts ate connected (2). 

Another type of electronic connector joins coaxial conductors. These have a soHd or stranded center-conductor surrounded by a dielectric. The dielectric is covered with a conductive shield made of metal braid or tape and with a layer of insulation. Coaxial cable connectors terminate the center-conductor and the shield. These are used primarily in radio frequency circuits. The shape, dimensions, and materials of an electronic connector shell or stmcture may have to be designed to shield the connection from electromagnetic and radio frequency interferences in many appHcations. 

Considerable effort has been directed to determining the causes of connection failutes and to learning how to minimize the likelihood of occurrence. Acceptable failute rates range from <1 in 10 operating hours for contacts in air-frame (31) electrical systems and in some telecommunications equipment, to 100—1000 in 10 operating hours in instmments, to even larger rates for contacts in many consumer products. A failute is defined as exceedance of contact resistance, which can be as Httle as twice the initial contact resistance, that causes circuit malfunction. The required lifetimes of connectors may be >20 yr, although most required appHcation times ate shorter (see Materials reliability). 

It is not practical to determine the contact resistance in power connectors. The resistance of the connection of a specified length of conductor on each side of the connector is measured and is called the overall resistance or the connection resistance. One industry specification (32) defines the included lengths and requites the stabiUty of the connection resistance to be within 5% of its average value throughout the heat-cycle test. 

The anodes most suitable for burying in soil are cylindrical anodes of high-silicon iron of 1 to 80 kg and with diameters from 30 to 110 mm and lengths from 250 to 1500 mm. The anodes are slightly conical and have at the thicker end for the current lead an iron connector cast into the anode material, to which the cable connection is joined by brazing or wedging. This anode connection is usually sealed with cast resin and forms the anode head (see Fig. 7-2). Ninety percent of premature anode failures occur at the anode head, i.e., at the cable connection to the anode [29], Since installation and assembly costs are the main components of the total cost of an... 

In addition to anodes with a simple connecting head, there are cylindrical double anodes that have cable connectors cast on at both ends and that can be used in the construction of horizontal or vertical anode chains. Anodes of graphite or magnetite are more compact than anodes of high-silicon iron because of the danger of fracture. 

Flexible cord approved for extra-hard service, flexible metal conduit, and liquidtight flexible conduit for limited flexibility. A suitable grounding conductor must be provided inside the flexible cord s outer jacket. Flexible conduit must be bonded with an external jumper or an approved internal system jumper external bonding jumpers are disallowed for flexible conduit exceeding six feet. Typical liquidtight and flexible cord connectors and an explosion-proof flexible connection are shown in Figure 17-23. 

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