Flexible containers

Dry oxahc acid is packed and sold in polyethylene-lined, multilayered 25-kg paper bags or in polyethylene-lined 300—600-kg PVC flexible containers. It should be stored in a cool, dry, ventilated place. For storage of its solutions at ordinary temperature, 316 stainless steel is often used as a constmction material. 

Toothpastes are packaged in flexible tubes, other flexible containers, and mechanically operated pump dispensers. They are usually extmded as cylindrical ribbons of a cohesive, smooth paste, approximately 2.54 cm in length and weighing approximately 1.5 g. New or modified dispensing devices are continually introduced to increase consumer interest. 

Shipment. The shipment of porcelain enamel is typically in 45-kg (100-lb) three-ply paper bags. More recently, 227-kg (500-lb) multi-ply cardboard barrels and bulk bags made of high strength woven polymers have been used. Porcelain enamel frit, powder, and premixed and premilled mill additions ate shipped in these flexible containers. 

T oods packaged in flexible containers and processed for commercial sterilization are a part of the trend toward improved quality in convenience foods. The retorted pouch has the package integrity of the metal can coupled with the food quality, reheating, and serving convenience of frozen, boil-in-the-bag foods (1). Its use for combat rations has especially interested military R D personnel because of the functional advantages over the metal can (2). 

The components of the plant cell wall (8-21) are the middle lamella (intercellular substance), the primary wall, and the secondary wall. The middle lamella is the pectic layer between cells and holds adjoining cells together as do membrane carbohydrates. The primary wall is thin (1-3 pm) and flexible containing cellulose, hemicelluloses, pectins, and glycoproteins. This wall provides mechanical strength, maintains cell shape,... 

Three flexible containers are used for gases. The containers are at the same temperature and pressure. One container has 2.0 g of hydrogen, another has 32.0 g of oxygen and the third has... 

Aldosterone influences electrolyte balance in the body. Specifically, aldosterone increases the excretion of potassium by the kidney but decreases the excretion of sodium by this organ. One result is the net retention of water. The action of mineralocorticoids tends to increase blood pressure. Basically, the more sodium you retain, the more water you retain. Retaining water tends to increase the fluid level in the vascular system and that increases blood pressure. Think about the pressure changes that happen when you continue to fill a flexible container such as a balloon with water the more water, the greater the pressure in the balloon. You might well imagine that an... 

In Japan, sulfamic acid is produced and supplied in crystal form. It is packaged in 25-kg net weight paper bags and in 600-kg, 700-kg, and 750-kg resinous flexible containers. The truckload price (fob Japan) is 1—2/kg. Three principal uses of sulfamic acid are in chemical cleaning, as sulfonation reagent, and for use in synthetic sweetener. 

A change to a flexible container system (bag) from another container system. 

OXALIC ACID. [CAS 144-62-7]. Oxalic acid, HOOC-COOH, or ethanedioic acid, mol wt 90.04, is the simplest dicarboxylic acid. It is soluble in water, and acts as a strong acid. This acid does not exist in anhydrous form in nature and is available commercially as a solid dihydrate, O2H2O4-2H2O, mol wt 126.07. The commercial product is packed in polyethylene-lined paper bags or flexible containers. Anhydrous oxalic acid can be efficiently prepared from the dihydrate by azeotropic distillation in a low boiling solvent that can form a water azeotrope, such as benzene and toluene. 

Many of the difficulties encountered in dry-pressing can be avoided by some form of isostatic-pressing. Ideally, this simply involves the application of hydrostatic pressure to powder in a flexible container. Powder movement is minimal and side-walls are absent. In practice shapes are often produced by the use of rigid mandrels as illustrated in Fig. 3.4. Powder is weighed into a rubber bag with a rigid mouth and a mandrel is then inserted and makes a seal with the mouth. Pressures of 20-280 MPa ( 200-2800 atm) can be applied through either liquid or gas media. The pressure must be released slowly since the air originally... 

The residue consists of mainly carbon and has a high heating value, as shown in Table 26.12. However, applications could not be found and the residue was landfilled as waste, after cosily packaging in a flexible container because the residue was a fine dry powder and caused dusl problems upon handling. The codevelopment work with Sapporo city successfully utilized the residue in the sludge incinerator as supplementary fuel. However, dust was still a problem in this application. To resolve the problem and to find belter applications, pelletizing facilities for this residue were installed in April 2004. As a result, the dust problem was solved and better applications are expected. 

The capsules in HCP may use either rigid containers or flexible containers. Fig. 3 shows a 7 in.-diameter steel capsule tested for grain transport in an 8 in. steel pipe at the University of Missouri-Columbia (UMC). With rigid containers, a second pipeline is needed to return the empty capsules, as is the case with PCP. If flexible containers made of plastic film are used to hold... 

The pressure of 6.0 L of an ideal gas in a flexible container is decreased to one-third of its original pressure, and its absolute temperature is decreased by one-half. What is the final volume of the gas ... 

Increasing or reducing the pressure within a pack, e.g. a reduction of pressure within a pack can occur if a warm or hot fill is employed or if a flexible container is compressed during capping. 

Capping a flexible container whereby the container is compressed, flexed or distorted (i.e. squats) to an extent that the content momentarily occupies more volume in the container. Thus if a good seal is then obtained, a partial vacuum can then be created in the pack. This type of operation may be extremely sensitive for plastic containers which show changes in wall thickness and compress (e.g. concertina) easily. 

If flexible containers are used, their arrangement may be such that they contract or dilate by the application of pressure. Whether the tooling is an integral part of the press or loaded and removed during each compaction cycle determines if it is a dry bag or wet bag process. The difference between the two methods is illustrated in Fig. 8.147. 

In the dry bag process, the flexible container is fixed in the pressure vessel and the powder is loaded directly. The tool forms a membrane between the fluid and the powder. Optionally, the flexible container may be placed inside of a primary diaphragm so that the powder never comes in contact with the fluid, even if the flexible mold is damaged or breaks. Therefore, dry bag tooling also has the advantage that the fluid is not contaminated with the powder. However, because the container must stand up to many pressing cycles and since changing it is time consuming, it has to be made of a very durable material. 

The wet bag pressing of large and/or complex shapes in which the flexible container is filled and prepared outside the pressure vessel and then immersed in the fluid and compacted. 

Today, the best method of overcoming the problem of uneven densities in a green body is isostatic pressing. In this compaction process, the pressure is applied by a fluid that is pressurized and acts uniformly from all sides on dry particulate solids that are enclosed in a flexible container ( mold ) immersed in the fluid [B.13a]. This results in the most uniform consolidation possible. Of course, there is still a density gradient across the part, the center is always less compacted than the surface, but the gradient is uniform and, typically, does not cause distortion during sintering. 

If flexible containers are used, their arrangement may be such that they contract or dilate under the application of pressure. Whether the tooling is an integral part of the... 

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