Totally Enclosed Manner

The regulations reiterate the statutory ban on the manufacture, processing, distribution in commerce, or use of PCBs in other than a totally enclosed manner, a phrase defined by EPA as any manner that will ensure no exposure of human beings or the environment to any concentration of PCBs. Examples of activities that are determined to be totally enclosed include the following  

If an activity is not conducted in a totally enclosed manner, it must be authorized or must qualify for an exemption, with the exception of the use, processing, and distribution of excluded PCB products, excluded manufacturing processes, recycled PCBs, and certain uses of sewage sludge containing PCBs. 

In many instances, the use authorization provides that PCBs may only be used in such equipment at concentrations less than 50 ppm and that servicing 

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Under Section 6(e)( 1), within six months of the effective date of the Act, EPA is obligated to promulgate rules that prescribe methods for the disposal of PCBs and require PCBs to be marked with clear and adequate weimings, as well as with instructions with respect to their processing, distribution in commerce, use, or disposal. Section 6(e)(2) provides that, one year after the effective date of the Act, no person may manufacture, process, distribute in commerce, or use any PCB other than in a totally enclosed manner. Section 6(e)(3) provides that no person may manufacture any PCB after two years from the effective date of the Act, or process or distribute in commerce any PCB after two and one-half years after such date. The provisions of Sections 6(e)(1) and 6(e)(2) allow the Administrator to promulgate rules granting exemptions from the control measures mandated by Section 6(e). 

Of the myriad of chemical substances regulated under TSCA, PCBs are subject to unique treatment. Indeed, upon enactment of TSCA, Congress prohibited the manufacture, processing, distribution, and use of PCBs in any manner other than a totally enclosed manner, subject to exceptions that may be issued by EPA if it finds that such exception would not result in an unreasonable risk of injury to health or the environment. These restrictions were unique because at the time TSCA was passed it did not single out any other chemical for a ban in this maimer. 

These broad statutory prohibitions are subject to limited exceptions that may be created by the EPA. Section 6(e)(2)(B) of TSCA allows EPA to authorize by rule the continued use of PCBs in a non-totally enclosed manner if the EPA finds that no unreasonable risk of injury to health or the environment would result. Section 6(e)(3)(B) also permits the Administrator to grant case-by-case exemptions to the statutory prohibitions on manufacturing, processing, and distribution. Such an exemption, which may be granted for one year, subject to additional terms and conditions, may be made upon a finding that (i) an unreasonable risk of injury to health or the enviroiunent would not result and (ii) good faith efforts have been made to develop a... 

A) Except as provided under subparagraph (B), effective one year after January 1, 1977, no person may manufacture, process, or distribute in commerce or use any polychlorinated biphenyl in any manner other than in a totally enclosed manner. 

B) The Administrator may by rule authorize the manufacture, processing, distribution in commerce or use (or any combination of such activities) of any polychlorinated biphenyl in a manner other than in a totally enclosed manner if the Administrator finds that such manufacture, processing, distribution in commerce, or use (or combination of such activities) will not present an unreasonable risk of injury to health or the environment. 

C) For the purposes of this paragraph, the term totally enclosed manner means any manner which will ensure that any exposure of human beings or the environment to a polychlorinated biphenyl will be insignificant as determined by the Administrator by rule. 

Under section 6(e)(2) of TSCA, the EPA allows the use of PCBs in a totally enclosed manner such as transformers, capacitors and electromagnets based upon considerations of cost and risk reduction. 

A dust-ignition-proof machine is a totally enclosed machine whose enclosure is designed and constructed in a manner which will exclude ignitable amounts of dust or amounts which might affect performance or rating, and which will not permit arcs, sparks, or heat otherwise generated or liberated inside of the enclosure to cause ignition of exterior accumulations or atmospheric suspensions of a specific dust on or in the vicinity of the enclosure. 

Paralleling 6(e), the regulations provide that no persons may use any PCB, or any PCB Item regardless of concentration, in any manner other than in a totally enclosed matmer within the United States unless authorized. Exceptions to the authorization requirement are provided for excluded manufacturing processes and excluded PCB products. 

Since compressed air is supplied by a compressor. Great care must be taken to insure certain types of equipment are operating in a safe manner. Safety devices for a compressed air system should be checked frequently. Compressors should be equipped with pressure rehef valves and pressure gauges. The air intakes must be installed and equipped so as to ensure that only clean uncontaminated air enters the compressor. Air filters installed on the compressor intake cilitate this. Before any repair work is done on the pressure system of a eompressor, the pressure is to be bled off and the system locked-out. All compressors must be operated and lubricated in accordance with the manufacturer s recommendations. Signs are to be posted to warn of the automatic starting feature of compressors. The belt drive system is to be totally enclosed to provide protection fiom any contact... 

In a manner similar to that nsed to calculate the density of a nnit cell, we can calcn-late the density of atoms on a plane, or planar density. The perpendicular intersection of a plane and sphere is a circle, so the radius of the atoms will be helpful in calcnlat-ing the area they occnpy on the plane. Refer back to Example Problem 1.4 when we calcnlated the lattice parameter for a BCC metal. The section shown along the body diagonal is actually the (110) plane. The body-centered atom is entirely enclosed by this plane, and the comer atoms are located at the confluence of four adjacent planes, so each contributes 1/4 of an atom to the (110) plane. So, there are a total of two atoms on the (110) plane. If we know the lattice parameter or atomic radius, we can calculate the area of the plane, Ap, the area occupied by the atoms, Ac, and the corresponding... 

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