Polyethylene enclosure

In each study, three transparent polyethylene enclosures (4.5 m deep, 2 m diameter, ca. 11 m3, 90% PAR) were filled with unfiltered fjord water... 

Overlapping flap, minimum 2 ft wide, at polyethylene enclosures for personnel access... 

A mesocosm is an enclosure containing a well-defined amount of the environment being investigated (in this study it was seawater) which is maintained at close to natural conditions, but for which environmental factors can be controlled and manipulated. It therefore provides a bridge between laboratory-based and real-world measurements. In this study, the mesocosms were sirrqily nine polyethylene enclosures (- 20 m watCT volume each, with - 4.3 m headspace volume). 

A composite dmm is constmcted of a plastic, semirigid inner liner (usually polyethylene) and either a steel or fiber outer container or overpack. The composite dmm may be a useful compromise between a plastic dmm and a conventional steel dmm. It is strong enough to be handled like a steel dmm, yet provides an enclosure for chemicals that cannot be shipped safely in steel or fiber dmms. Capacities of composite dmms are 19—208 L (5—55 gal). Such dmms are used in chemical, pharmaceutical, and food industries. 

The principal use of LDPE and LLDPE in building products is as a film water barrier under below-grade doors as a wall vapor barrier, though PVC is typically preferred and as temporary enclosure film during constmction. The film is made either by extmding a thin-waHed tube, which may be sHt or wound up direcdy, or by extmsion through a slot die and cast direcdy on to a cold roU, cooled, then wound up. The former method is more widely used. A much smaller use for low density polyethylene is in piping. 

Electrical Applications. Plastics are used for electrical insulation, conduit and enclosures, lighting fixtures, and mechanical devices. The most widely used plastic for wire and cable insulation is flexible, plasticized PVC, which constitutes well over half the market in insulating wires for buildings, automobiles, appHances, and power and control lines. Polyethylene is also a factor. Higher performance plastics such as nylon and fluoropolymers also play a smaller role in this area. 

Bottle systems are more varied, whether for glass, polyethylene terephtha-late (PET) or other plastic. Bottles are rinsed with oxonia solution and then sterile water prior to filling. The filler is generally of a non-contact type (it does not touch the bottles) and product is either weighed in or measured volumetrically. Caps are also chemically sterilised (unless a foil closure is used) and applied on a capper monoblocked with the filler, enclosed in a high efficiency pure air (HEPA) filtered enclosure. The filler and final rinser are in a class 100 room and file operator wears full protective clothing to prevent infection of the product. 

The main concept of the box design is to maximize the area of constant pressure, which is exerted by the polyethylene bag, in order to provide a reasonable zero-slope flow rate. Consequently, a rectangular box enclosure was used, because the forces would be transferred perpendicularly to most of the surface of the drug bag. This also explains why two bags were used instead of one. 

Two heavy steel plates 1.8 are held 5 or 15 cm apart. Tlie plates arc in a gaslight enclosure formed from steel sides with sheet polyethylene. The explosive cartridges are in the groove. The space inside the enclosure is filled with an explosive gas mixture. The ignition or non-ignition of the gas mixture is observed. 

A calculation—and it is only a mathematical exercise— shows that if a single matchbook is enclosed in a 2 mil (0.002 in.) thick envelope of the best grade of polyethylene with 100 cm total surface area and exposed to 98% RH, assuming an average interior RH of 55% (1 cm Hg of water vapor pressure differential), the influx of moisture per week would be 28 mg or 0.7% of the weight of the enclosed paper and chemicals. This proves the above-raised point that prolonged, uninterrupted, severe exposure cannot be counteracted by plastic enclosure. 

The spent fuel neutron counter (SFNC) is a prototype neutron-detector system that verifies closely packed spent fuel assemblies stored in a spent fuel pond (Ham et al. 2002). The system contains a fission chamber moderated by a polyethylene cylinder housed in a watertight stainless steel enclosure. The SFNC measures total neutron signals from long-cooled spent fuel assemblies while in their storage position, without requiring them to be moved. The technique can detect a missing fuel assembly. These measurements are performed underwater in a gap between four assemblies. 

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