Filter temporary

In addition, all of the process raw materials must be clean and not iatroduce contaminants. The raw materials and temporary coatings must also be defect-free, and these have to be manufactured under similar conditions so that no contaminants are iatroduced. The solvents used to clean the substrate and develop the resists must be filtered and pure. Care must also be taken to ensure that no trace compounds or elements are present that may affect the electronic properties. The specific type of coating aid, the type of functional coating, and the process used to apply the functional coating are all widely varied ia actual practice. 

Surface cleaning as a preparation for coatings is discussed in Sections 11.1 and 11.2. It is important to control degreasing baths to prevent accumulation of water and formation of corrosive products which will contaminate the atmosphere as well as the objects being degreased. In the case of tri-chlorethylene, stabilisers are added to prevent formation of hydrochloric acid Exclusion of dust is beneficial, and may necessitate filtering the air or use of a temporary protective. 

Filter and dry. Check PEG-bound product by NMR and repeat glycosylation if necessary. Remove temporary protecting group and continue second cycle. 

After the bomb has been cooled the contents are removed and allowed to stand until the catalyst has settled (Note 5). The mixture is filtered, and the filtrate is transferred to a Claisen flask placed in an oil bath. The solvent is removed by distillation at atmospheric pressure, and the oil-bath temperature is raised to 200°. After temporary cooling, the residue in the flask is distilled under reduced pressure. The 5,5-dimethyl-2-pyrrolidone boils at 126.5-128.5°/12 mm. and solidifies in the receiver. The yield is 84-92 g. (88-96%) m.p. 42-43° (Note 6). 

Lime-soda process. Combination of the use of slaked lime for the removal of temporary hardness and sodium carbonate for the removal of permanent hardness constitutes the lime-soda process for softening natural waters. This method is commonly used in municipal water-treatment plants and is a cheap and yet fairly effective process. If sufficient time can be allowed, the insoluble carbonates may be permitted to settle out in settling basins, or they may be more rapidly removed by means of filters. Frequently, iron or aluminum salts are added, and these hydrolyze to form gelatinous precipitates of ferric or aluminum hydroxides. As these precipitates slowly settle, they carry with them the insoluble normal carbonates, as well as any other suspended matter such as sand, clay, or organic matter which is sometimes slow in settling otherwise. 

Just before a plant startup, the operations team wondered if the piping upstream of a flammable gas compressor may not have been cleaned sufficiently to prevent dirt from entering the precision machinery. Concerned employees had a temporary filter installed in the suction line. The operations team was correct there was a sufficient amount of foreign material in the upstream piping to plug up the filter. [8]... 

Unfortunately the temporary filter was placed between the compressor and a low suction pressure trip. The compressor suction pressure was reduced to a vacuum and air intruded into the system. The air reacted within the system. A decomposition occurred further downstream and a major fire caused many months delay in the startup of this unit. 

Should the water be so hard that 8 c.c. upwards of soap solution are required, a smaller volume than 50 c.c. should be taken and diluted to tins amount with freshly boiled distilled water. Reference to the table indicates the amount of hardness corresponding to each titration. The total hardness is given by this method. If a second sample of water be boiled and after settling or filtering titrated m a similar manner, the permanent hardness is obtained. Subtraction gives the temporary hardness. 

Short cycles can be caused by temporary or permanent stoppage of body feed addition, blinded septa, changes in characteristics of the liquid being filtered, entrapment of air in the filter, which will decrease the filter area, and too high a filtration rate. 

Factors That Determine the Particle Size of Precipitates The particle size of solids formed by precipitation varies enormously. At one extreme are colloidal suspensions, whose tiny particles are invisible to the naked eye (10 to 10 cm in diameter). Colloidal particles show no tendency to settle from solution and are not easily filtered. At the other extreme are particles with dimensions on the order of tenths of a millimeter or greater. The temporary dispersion of such particles in the liquid phase is called a crystalline suspension. The particles of a crystalline suspension tend to settle spontaneously and are easily filtered. 

---