Flow wrapping

Films and labels for a wide range of applications in the film market including labels, heat-seal overlays, window films, flow wrap, twist wrap and formulations for carrier bags. 

In 2005, SPAR Austria started packaging organic apples, pears and tomatoes in rigid trays sealed with a flow wrap film made from NatureWorks PLA. Research showed that consumers perceive that nature-based packaging enhances the appeal of fresh food, and strongly prefer products packaged in biodegradable plastic containers. 

NatureFlex films are also stiffer and more oriented than some other biopolymers, which make them suitable for use on standard flow-wrap and form-fill-seal equipment. 

Pack A (with flow Pack B (no flow wrap) Storage... 

Sachets also have the advantage that they can be used for liquid and semi-liquid packaging. Flow wraps are a further extension of a sachet-type pack. Both have been widely used as a protective overwrap to extend the shelf life of blisters. 

Bars and stick products are flow-wrapped. The printed wrapping, which may be coated paper, orientated polypropylene or metallized film, is supplied as a long roll. The wrapping is unwound from the roll and made into a continuous tubular sleeve (Figure 5.17a). Products are placed in the sleeve (Figure 5.17b), which is heat or pressure sealed along its seam. Finally, the tube is cut across to separate the products and the ends of the wrapping are sealed. 

Figure 5.16 Examples of common types of ice cream packaging (a) flow wrap, (b) a cone sleeve and a tube, (c) tubs and (d) a dessert container...

Figure 5.17 Flow wrapping (a) the wrap comes off the roll and is shaped into a sleeve ...

BioPeel is a clear, peelable PLA lidding or flow-wrap film, suitable for use with chilled and frozen products such as fruif vegetables, salads, and sandwiches. BioPeel has a broad sealing window and clarity, is available with antifog, and can be perforated. BioPeel can be tailored to seal and peel to any type of container. 

Several wick stmctures are in common use. First is a fine-pore (0.14—0.25 mm (100-60 mesh) wire spacing) woven screen which is roUed into an annular stmcture consisting of one or more wraps inserted into the heat pipe bore. The mesh wick is a satisfactory compromise, in many cases, between cost and performance. Where high heat transfer in a given diameter is of paramount importance, a fine-pore screen is placed over longitudinal slots in the vessel wall. Such a composite stmcture provides low viscous drag for Hquid flow in the channels and a small pore size in the screen for maximum pumping pressure. 

Bacteriological sampling is performed by manual techniques because of stringent sterilization requirements. Samples are taken in wide-mouthed, sterile, glass-stoppered bottles that are wrapped in paper prior to sterilization in an autoclave at 138 kPa (20 psi) or in an oven at 170°C. The botde is unwrapped and the lower portion is held in the hand. The sample is taken with the botde mouth in the direction of the flow. The stopper must be protected from contamination, the botde only partially filled, and the sample stored at 4°C after sampling. For bacteriological samples withdrawn from a tap, the water should mn for five minutes and then be shut off the tap should then be sterilized by flaming before a sample is taken. 

For very low Reynolds numbers, 7 . << 1, the flow lines wrap smoothly around the cylinder, as shown in figure 9.1. 

When large areas of the membrane are depolarized in this manner, the electrochemical disturbance propagates in wave-like form down the membrane, generating a nerve impulse. Myelin sheets, formed by Schwann cells, wrap around nerve fibers and provide an electrical insulator that surrounds most of the nerve and greatly speeds up the propagation of the wave (signal) by allowing ions to flow in and out of the membrane... 

At the heart of an automotive catalytic converter is a catalyzed monolith which consists of a large number of parallel channels in the flow direction whose walls are coated with a thin layer of catalyzed washcoat. The monolith catalyst brick is wrapped with mat, steel shell and insulation to minimize exhaust gas bypassing and heat loss to the surroundings. 

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