Saturated water vapour, 4.18

Fig. 5.17 Adsorption of water vapour at 25°C on samples of nonporous silica (TK 800). (a) The sample had been exposed to nearly saturated water vapour (p/p° = 0-98) before determination of the isotherm, (b) The sample had been outgassed at 1000°C. (Some points omitted for clarity.)...

The effect of these factors on the adsorption isotherm may be elucidated by reference to specific examples. In the case of the isotherm of Fig. 5.17(a), the nonporous silica had not been re-heated after preparation, but had been exposed to near-saturated water vapour to ensure complete hydroxylation. The isotherm is of Type II and is completely reversible. On the sample outgassed at 1000°C (Fig. 5.17(h)) the isotherm is quite different the adsorption branch is very close to Type III, and there is extrensive hysteresis extending over the whole isotherm, with considerable retention of adsorbate on outgassing at 25°C at the end of the run. 

The water produced is, however, liquid, hence we must take H3 as the concentration of saturated water vapour at the given temperature, since the liquid water produced could be evaporated to form vapour at this concentration without additional work, except that due to the change of volume under the given pressure, viz., 2RT, which must now be omitted fron the RT2)r . 

Blister Box Test, according to ASTM D 4585 (ISO 6270). This test evaluates the water resistance of a coat by condensation of water vapour. The panel surface with the coating system is exposed to 40°C, saturated water vapour, at an angle of 15° to the horizontal. The reverse side of the panel is exposed to room temperature. At each inspection blisters and rust are evaluated according to ASTM D 714 (ISO 4628-2) and ASTM D 610 (ISO 4628-3) respectively. Cracking is evaluated according to ISO 4628-4. When the test is stopped, adhesion is evaluated according to ASTM D 3359, tape test (ISO 2409) or ASTM D 4541 (ISO 4624), pull-off test. 

The solubility of hematite was measured in NaOH/NaCl (0.007-2 m) at between 60 and 300 °C at saturated water vapour pressure with the dissociation reaction being described by ... 

PRESSURE OP SATURATED WATER VAPOUR IN EQUIRIBLIUM WITH WATER AT VARIOUS TEMPERATURES, DEGREES CELSIUS... 

The above material is expected to have excellent diffusion resistance to gases such as sulfur dioxide, nitrogen oxides and saturated water vapour and outstanding chemical resistance to mineral acids, bases, aqueous phases and polar solvents and weatherproof. 

Excellent diffusion resistance to gases such as sulfur dioxide, nitrogen oxides and saturated water vapour ... 

While conductometric responses of coated and uncoated gold layers on exposure to mercury vapour are similar, a strong difference in then-responses to other compounds is observed (Fig. 12.6). No response of the coated sensors to saturated water vapour was detected (Fig. 12.6a). Also in contrast to the uncoated sensors, practically no effect of either vapour of sulphuric acid (Fig. 12.6b) or butanethiol (Fig. 12.6c) on the coated sensors was observed. The effect of iodine vapour was not changed. 

Dietericis found the density of saturated water vapour at 0° C. as 4 8856 mg. /lit. by determining the weight of water evaporated in an ice calorimeter (the heat change giving the weight) to fill a known volume in an evacuated bulb. This is 204 68 Iit./g. 

The density of saturated water vapour at 100° is almost exactly normal. i Up to about 40° the density in g. per m. is approximately equal to the vapour pressure in mm. Hg. ... 

Difficult environments for sealant materials are long-term immersion in water or continuous exposure to high humidity. A sealant immersed in water or exposed to saturated water vapour will be subject to physical, chemical and biochemical changes. The useful life of a sealant will depend on the relative levels of these effects, which in turn will depend on the type of polymer used and the formulation. The changes may occur in bulk or on the surface, and may lead to a loss of adhesion, which is the most damaging result of attack by water (Lee et al., 1992). 

From equation (9) it is easy to calculate that the specific heat of saturated water vapour, for example, is negative at the normal boiling point. Thus for 1 gr. of water vapour at 100° C., we have... 

By the compression of 1 gr. of saturated water vapour at 100° to saturated water vapour at 101°, we have an emission of 1-2 cal. If this heat is not allowed to escape, we do not obtain saturated water vapour at 101°, but superheated steam at a correspondingly higher temperature. Conversely, if we allow saturated water vapour to expand adiabatically, condensation takes place. We may mention that this spontaneous condensation of water vapour, which for a slight expansion takes place only in the presence of dust particles or ions, has been successfully employed in counting the number of ions or nuclei in the vapour. 

The ratio of the actual water vapour pressure of the air to the saturated water vapour pressure of the air at the same temperature expressed as a percentage. More simply put, it is the ratio of the mass of moisture in the air, relative to the mass at 100% moisture saturation, at a given temperature. standard operating procedure (SOP)... 

The Thermal Properties of Saturated Water Vapour (Steam)... 

If the reaction were made to take place under such circumstances that all the substances were pure liquids or solids, the affinity A of the reaction is given by (1 e the affinity of formation of 2 moles of H20)— A = RT log K - RTSv log Caaturated Now exactly as m the case of the dissociation of the carbonates, the term for the concentration of saturated water vapour present in both of the above terms cancels The term log C may therefore be taken as equivalent to-... 

Table 3.3. Dependence of saturated water vapour pressure on temperature...

Measurements in a vacuum were performed with an STA 429 thermal analyser, and those in air, with STA 429 and 449 thermal analysers. The partial water-vapour pressure in air was estimated from the relative humidity (measured with a hygrometer) and tabulated pressures of saturated water vapour at the temperatures in the room (see Appendix, Table A6). 

The original Wexler s equation published in 1971 [8] has been revised in 1976 [9], and updated in 1998 with coefficients computed for the International Temperature Scale of 1990 (lTS-90) [10]. This updated version of Wexler s equation has been used to calculate the saturation water vapour pressure Ps for each mean daily temperature, and also to calculate the partial water vapour pressure Pd at the same time point and place by taking the corresponding daily dewpoints instead of the temperature. 

Rotary vane vacuum pumps are always tailored for the specific application. The optimisation of a rotary vane vacuum pump with recirculating lubrication for extracting saturated water vapour under suction conditions is described below by way of example. 

The higher differences, in phase composition are observed in the pastes autoclaved in the saturated water vapour at temperature range 120-200 °C. The phase composition of the calcium sihcate hydrates is primarily the function of C/S in the starting mixture. In Portland cement paste without additions the C-S-H (I) is transformed quickly to the C-S-H (II) and the latter already at 25 °C into a-C2SH [194, 199]. The proper addition of the ground quartz gives the 1.1 nm tobermorite. This phase contains aluminium in solid solution, which causes the transition to xonotlite, at temperatures exceeding 160 °C difficult... 

The cause of delayed ettringite formation was elucidated based on the ettring-ite stability in concrete. As it is known, ettringite is stable at least at temperature 100 °C, in saturated water vapour [157]. However, Wieker et al. [151] found that ettringite is not stable at higher temperatures in the presence of alkalis. The results of these studies are presented in Table 6.2. 

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