Evaporators continuous

The evaporation rate from the gel is dictated by the difference between the vapor pressure at the evaporating surface, P, and the vapor pressure of the ambient atmosphere, P. Evaporation continues as long as at a rate, E), of... 

Relative humidity can have a significant impact on drying behavior and film quahty. Water-based formulations that perform weU when apphed under dry conditions may be deficient under high humidity apphcation conditions. The rate of water evaporation is much slower at high humidity, but solvent evaporation continues. This results in solvent depletion during the critical phases of film formation and consequent poor film development. 

All of us are familiar with the process of vaporization, in which a liquid is converted to a gas, commonly referred to as a vapor. In an open container, evaporation continues until all the liquid is gone. If the container is closed, the situation is quite different. At first, the movement of molecules is primarily in one direction, from liquid to vapor. Here, however, the vapor molecules cannot escape from the container. Some of them collide with the surface and reenter the liquid. As time passes and the concentration of molecules in the vapor increases, so does the rate of condensation. When the rate of condensation becomes equal to the rate of vaporization, the liquid and vapor are in a state of dynamic equilibrium ... 

The solution is filtered if not clear, and the cyanoacetic acid is set free (hood) by adding with thorough stirring 600 cc. (a slight excess) of commercial hydrochloric acid (sp. gr. 1.156). The solution is evaporated on a water bath at 60-70° (Note 3) under a pressure of 20 30 mm. and the evaporation continued until practically 110 more distillate (Note 4) comes over. To... 

The composition of the earth s atmosphere differs from day to day, from altitude to altitude, and from place to place. The largest variation is in the concentration of water vapor. Water evaporates continually from the hydrosphere, from the soil, from leaves, from clothes drying, etc. At intervals, parts of the atmosphere become chilled until the dew point or frost point is reached and then any vapor in excess of the saturation amount is precipitated as rain or snow. 

During evaporation of organic solvents, the temperature of the water-bath should be kept at 40 °C or lower. Once the solvent is evaporated, continued rotary evaporation may lead to reduced analyte recovery. 

In standard FAB, the surface of the matrix solution is depleted of analyte and suffers from radiational damage during elongated measurements. Refreshment of the surface proceeds by diffusion (limited by the viscosity of the matrix) or evaporation. Continuous-flow fast atom bombardment (CF-FAB) continuously refreshes the surface exposed to the atom beam. [107,108] The same effect is obtained in slightly different way by the frit-fast atom bombardment (frit-FAB) technique. [109,110] In addition, both CF-FAB and frit-FAB can be used for online-coupling of liquid chromatography (LC, Chap. 12) [111] or capillary electrophoresis (CE) to a FAB ion source. [112]... 

It is normal for additional potassium chloride to precipitate as the evaporation continues. 

A common fallacy arises that cooling towers cannot function when the inlet air is at its wet-bulb temperature. To the contrary, when air at the wet-bulb temperature enters the tower it acquires sensible heat from the hot water, thereby raising its temperature so that it is no longer saturated. Consequently, water evaporates continuously into the air phase as it ascends through the tower and cooling takes place. 

Phosphorus trichloride twice redistilled was mixed very slowly with specially purified water, the flat porcelain dish in which the addition was made being floated on cold water during the operation. It was found that, if the addition was made too rapidly, a discoloration was produced, which at the end of the preparation was seen to be due to a fine powder suspended in the liquid. The phosphorous acid was then heated until it gave no precipitate with silver nitrate. It was then oxidized by cautious addition of dil. nitric acid, when an active effervescence ensued. Nitric acid was eventually added in slight excess, and the evaporation continued until all the nitric acid was expelled. The phosphoric acid thus prepared was transparent and colourless. The 100 per cent, acid did not affect litmus paper, and had no action on sodium carbonate. 

PFO-rich domains are all ringed by ripple structures (Figure 2.4), which exhibit height variation on the order of 10 nm and a characteristic length-scale, A., of approximately 500-800 nm. We speculate that the formation of these features is attributed to the differences in solubility of the two polymers in the common solvent the less soluble component of the blend in the common solvent will first solidify and impose the domains architecture of the film. The other component still swollen at this time will then collapse as the evaporation continues. 

M2. Macheboeuf, M., Dubert, J. M., and Rebeyrotte, P., Microelectrophorese sur papier avec Evaporation continue du solvant (Electrorheophorese). II. Etude theorique. Application a la mesure des mobilites electrophoretiques. Bull. soc. chim. biol. 36, 346 (1953). 

For the estimation of volatile dialkyl nitrosamines and A-nitrosopiperidine, A-nitrosopyrrolidine and A-nitrosomorpholine, ION sulphuric acid was added to the sample which was then extracted with redistilled dichloromethane. 1.5m sodium hydroxide was added to the combined extract. After separation, the organic layer was dried over sodium sulphate and evaporated to 2.5mL at 46°C on a water bath. Hexane was added, and evaporation continued to about 250pL. Ahquots of 5pL were analysed for volatile nitrosamines using gas chromatography. 

Preparation from Carbohydrazide. One hundred seventeen grams of carbohydrazide (1.3 mols) and 108 ml. of 12 M hydrochloric acid (1.3 mols) are" mixed in a 400-ml. beaker equipped with a mechanical stirrer and a 360° thermometer. The mixture is heated slowly on a hot plate with constant stirring. At first, there is vigorous effervescence, which may cause spattering, but this gradually subsides as evaporation continues. The temperature rises to about 215° and remains there for approximately an hour. Heating is stopped when the temperature rises above 220°. The over-all time of reaction is 4 hours. To the cooled melt, 125 ml. of water is added, and the mixture is heated to effect solution of soluble by-products (principally hydrazine hydrochloride). After the solution has cooled to room temperature, the urazine is filtered and washed with water, ethanol, and ether. The yield of dry product is 55 g. (73%)- The product melts with decomposition at 271 to 272°. 

After the passage of the gas the liquid is evaporated in a platinum (or porcelain) capsule on the water bath to a volume of 2-3 ml. and then 2 drops of acetic acid are added and the evaporation continued almost to dryness. The residue is redissolved in 2-3 ml. water and again evaporated to dryness to decompose the sodium biacetate which is formed. The residue is once more dissolved in 2 ml. water, a drop of potassium chromate solution added and then titrated with N/40 silver nitrate. It is advisable to carry out a blank determination. The amount of phosgene present in the sample is calculated from the number of ml. of N/40 silver nitrate solution employed in titration. 

A large quantity (ca. 1000 Mg) of d-RDF had to be stored and stockpiled for a test burn for periods of ca. 1 year. Storage was outdoors, under cover of plastic sheeting, on a 100 m2 asphalt pad. The pile was originally 2 m high and later increased to 4 m. Moisture evaporated continuously and some condensed on the under surface of the plastic sheeting, forming a "cap" 15 -30 cm thick of wet pellets on the surface of the pile. 

A volatile compound evaporates continuously, even at room temperature. Higher temperature accelerates the evaporation. Some food ingredients such as lipids and proteins may hap flavor compounds to some extent and reduce their volatility. Different flavor compounds have different volatility. An aged food may not only lose its total flavor, but also change its proportions of the flavor components, resulting in a changed odor. 

Evaporation causing carbonate precipitation occurs in soils and surface waters. Line A-B in Fig. 6.7(c), positioned at atmospheric CO2 pressure (10 bar), describes the increase in Ca with evaporation. If evaporation continues to point B, calcite precipitation takes place according to the reaction... 

The emission rates of formaldehyde and VOCs from most indoor decorating and refurbishing materials are highest in new or renovated buildings. These compounds can outgas (i.e., evaporate continuously) slowly over months or years. As a consequence, the indoor concentration of these compounds slowly decreases, as shown in Tables 8 and 9. However, it can be also seen from... 

It may be shown that the vapour pressure exerted by a convex surface is greater than that exerted by a plane surface (Starling, 1935). This effect of the curvature of the surface is referred to as the Kelvin effect, and is of importance in considering the stability of small liquid droplets. If a very small droplet occurs in an atmosphere in which the vapour pressure is the maximum associated with a plane surface (SVP), evaporation from the surface of the droplet will still occur as a result of the vapour pressure exerted by the droplet surface exceeding the SVP. As the droplet becomes smaller, so the curvature of the surface increases and evaporation continues. This effect in part explains the observation that a dust-free vapour does not form droplets at a temperature below the normal temperature of condensation (the dew point). The Kelvin effect must be taken into account when considering the stability of small liquid aerosol droplets in the airways. 

When a gas is collected over water, some of the water evaporates and its vapor forms a mixture with the other gas. Evaporation continues until the rate of evaporation of the liquid water equals the rate at which the water vapor condenses, and a state of physical equilibrium is achieved. 

After completion of evaporation, continue the mixing of the mass under vacuum 0.4-0.6 bar while cooling it to 40° 2°C. 

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