Controlling Static Electricity

Charge buildup, resulting sparks, and the ignition of flammable materials is an inevitable event if control methods are not appropriately used. In practice, however, design engineers recognize 

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G. Luttgens and M. Glor, Understanding and Controlling Static Electricity (Goethestrasse, Germany Expert Verlag, 1989). 

Fibers emerging from the spinneret are cooled under controlled conditions, passing over guides and rollers to a take-up spool or bobbin. Often a finish is applied before windup to control static electricity and friction (Stevens 1993). Large-scale production machinery produces fiber at a rate of thousands of feet a minute. A schematic diagram of a melt-spinning apparatus is drawn in Figure 8-10. 

Leonard, C. G-, Controlling Static Electricity on Cotton During Ginning With an Antistatic Agent, USDA Agr. Res. Serv. Rpt. (1960), ARS 42-39, 16. 

Various industries make efforts to introduce static control to workplace, products and packaging. As many as 10% of the failures of electronic equipment are related to static electricity. To control static electricity in the work place, many products should be conductive (coatings, mats, bench tops, etc.). Packaging has been developed using conductive fillers. This creates new opportunities for manufacturers of products and fillers. 

For example ISO 1853, Conducting and antistatic rubbers, vulcanised or thermoplastic -Measurement of resistivity (in revision-DIS issued 1996). BS 2050. Electrical resistance of conducting and antistatic products made from flexible polymeric material. BS 2044. Determination of resistivity of conductive and antistatic plastics and rubbers (laboratory methods). An lEC standard is in draft giving comprehensive guidance. This is at present at the Committee draft stage—15D(Secretariat)37, Methods of test for the resistance of solid materials used to control static electricity. 

When faced with the potential for spontaneous ignition of hazardous vapors and dusts, controlling static electricity is critical. 

Fabric softening agents Soften, control static electricity in fabrics Quaternary ammonium compounds ... 

Kassebaum, J.H., Kocken, R.A., 1997. Controlling static electricity in hazardous (classified) locations. Ind. Appl. IEEE Trans. 33 (1), 209-215. 

Statexan ITA Static control agents Static decay Static decay times Static dissipation Static drying Static electricity Static eliminating devices Static mixers Static phenomena... 

Control of relative humidity is needed to maintain the strength, pHabiUty, and moisture regain of hygroscopic materials such as textiles and paper. Humidity control may also be required in some appHcations to reduce the effect of static electricity. Temperature and/or relative humidity may also have to be controlled in order to regulate the rate of chemical or biochemical reactions, such as the drying of varnishes, the appHcation of sugar coatings, the preparation of synthetic fibers and other chemical compounds, or the fermentation of yeast. 

Chemical treatments commonly appHed to cormgated paperboard packaging materials include additives that impart various degrees of water resistance, humidity resistance, oil and grease resistance, product abrasion resistance, product corrosion resistance, adhesion release properties, flame-retardant properties, nonskid properties, and static electricity control properties to the finished package (1,2). 

Humidification. Adding moisture to air has long been used to control static and to help dissipate static electricity in textile mills (see A IR conditioning). Moisture does not improve the electrical conductivity of the air, but it increases the electrical conductivity of materials absorbing moisture. 

Flammable liquids are considered particularly static-prone if their elec trical conductivity is within the range of 0.1 to 10 pS/m. If no particulates or immiscible liquid are present, these prodlic ts are considered safe when their conductivity has been raised to 50 pS/m or higher. Blending operations or other two-phase mixing may cause such a high rate of charging that a conductivity of at least 1000 pS/m is needed for safe charge dissipation (British Standard 5958, part 1, Control of Undesirable Static Electricity, para. 8, 1991). 

Static electricity Inert milling system generation both, Control/interlock with oxygen concentration in mill and con- monitoring veying equipment bond all electrically conductive components Use conductive materials of construction CCPS G-12 CCPS G-23 CCPS G-29 CCPS G-32 ISAS84.01 NFPA 654... 

Control humidity of air in operating area to reduce accumulation of static electricity... 

BS 5958. Code of Practice for Control of Undesirable Static Electricity. BSI, U.K. 

The purpose of this book is to assist the user in controlling the hazards associated with the generation, accumulation, and discharge of static electricity by presenting... 

Other areas such as static electricity and its use and control were not discussed since they represent a different type of application (2). As new materials became available and the electrical art continued to develop, the uses for plastics in electrical applications has increase both in the basic application as a dielectric and in special applications using the special intrinsic properties of the plastics. 

Code of practice for the control of undesirable static electricity. 

The nonelectric firing system is simple and requires a minimum of equipment. Once initiated, however, it passes from the control of the operator. The electric system can be retained in the control of the operator up to the actual firing. Electric caps also are more waterproof. On the other hand,-the electric system is more complicated, employs more equipment, and may require the operator to remain near the scene at the time of firing. In addition, electric systems can be accidentally activated by static electricity and are hazardous to use in some target situations. 

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