Moisture contamination

Specifications and Packaging. Aluminum chloride s catalytic activity depends on its purity and particle size. Moisture contamination is an important concern and exposure to humid air must be prevented to preserve product integrity. Moisture contamination can be deterrnined by a sample s nonvolatile material content. After subliming, the material remaining is principally nonvolatile aluminum oxide. Water contamination leads to a higher content of nonvolatile material. 

Before insulation is installed, carbon steel surfaces between 32°F and 200°F (0°C and 93°C) should be prepared and painted in accordance with manufacturer s recommendations. A vapor barrier should be provided over the outer layer of the insulation. Minimum thickness of insulation for fireproofing should be 2 in (5 cm). Moisture contamination to the insulation should be avoided to prevent damage to the insulation as a result of steam pressure caused by a fire. 

Cure Rate as Measured by Strength Development of Prototype Joints. Cure rate is an important factor when the expense of jigs and fixturing equipment is high or fast production rates are critical. It is also used as a quality control test to determine if the curing mechanism within the adhesive has changed from lot to lot or if it may have been spoiled by storage, moisture contamination, etc. 

There are certain plastics that, when compounded with certain additives such as color, could have devastating results. Day-to-night temperature changes is an example of how moisture contamination can be a source of problems if not adequately eliminated when plastic materials are exposed to the air otherwise it has an accumulative effect. The critical moisture content (average material moisture content at the end of the constant-rate-drying period) is a function of material properties, the constant-rate of drying, and particle size. 

Note 4. In this step care should be taken to avoid moisture contamination of the sample (van Zyl 1978). 

It is undesirable to re weigh the trimethylchlorosilane in the addition funnel because moisture contamination is possible. An excess of sodium azide is used in this preparation and the exact amount of the silane used is not critical. 

NIRS has proven to be a fast, reliable, and cost-saving method for numerous applications in the pharmaceutical industry. It is no longer the esoteric method it was once believed to be. The pharmaceutical industry has learned a great deal about NIRS from the agricultural and food industries. Concepts and techniques have been borrowed and fitted to the needs of pharmaceutical scientists. Users in all disciplines face common issue, such as calibration transfer, moisture contamination, particle size, and the rigors of calibrating multiple constituents. 

Fig. 3 Moisture contamination vs. bearing life. (View this art in color at www.dekker.com.)...

The cells for use in visible and ultraviolet spectrometers are usually cuvets 1 cm thick internal distance between parallel walls), although cells of different pathlengths and volumes can be used. These are illustrated in Figure 16.16. For infrared instruments, various assorted cells are used. The most common is a cell of sodium chloride windows. Fixed-thickness cells are available for these purposes and are the most commonly used. The solvent, of course, must not attack the windows of the cell. Sodium chloride cells must be protected from atmospheric moisture (stored in desiccators) and moist solvents. They require periodic polishing to remove fogging due to moisture contamination. Silver chloride windows are often used for wet samples or aqueous solutions. These are soft and wUl gradually darken due to exposure to visible light. 

Storage Store under nitrogen to eliminate moisture contamination Zoldine RD-20 [ANGUS]... 

Any moisture contamination of the cell has a deleterious effect on its operation. Therefore, all cell assembly operations are usually carried out in a dry room or dry box. Alternatively, the cell then may be put in a heated vacuum oven for 16-24 h in order to extract residual water from the cell core before electrolyte filling. In the next process, the cell is filled with the electrolyte using a vacuum injection apparatus. Electrolyte is added to the cell by a precision pump and then vacuum filled to ensure that the electrolyte permeates and completely fills the porosity in the separator and electrode structures. Precision pumps meter the exact amount of electrolyte needed for good cell operation. The electrolyte salt usually is LiPF dissolved in a... 

Lechner-Knoblauch and Heitz (1987) have studied the effect of impurities such as chlorides and organic acids on the corrosion rate in CH3OH and C2H5OH, both at 50°C and at room temperature. At acid contamination levels of 0.1 mol/L, corrosion rates could reach 1 p.m/h or more, but at 0.01 mol/L, 0.03 p.m/h was more typical (Table 5.8). It has also been shown that the presence of water may cause a marked increase in the corrosion of zinc in organic chemicals. Therefore, the possible effect of moisture contamination should be considered in using the data from Table 5.6. Constantinescu and Heitz (1976), in tests on formic, acetic, proprionic, and butyric acids, showed that water has a significant effect on the corrosion by monocarboxylic acids with three or more carbon atoms. 

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