Conversion factors, vaporizers

The water-vapor transmission rate (WVTR) is another descriptor of barrier polymers. Strictly, it is not a permeabihty coefficient. The dimensions are quantity times thickness in the numerator and area times a time interval in the denominator. These dimensions do not have a pressure dimension in the denominator as does the permeabihty. Common commercial units for WVTR are (gmil)/(100 in. d). Table 2 contains conversion factors for several common units for WVTR. This text uses the preferred nmol/(m-s). The WVTR describes the rate that water molecules move through a film when one side has a humid environment and the other side is dry. The WVTR is a strong function of temperature because both the water content of the air and the permeabihty are direcdy related to temperature. Eor the WVTR to be useful, the water-vapor pressure difference for the value must be reported. Both these facts are recognized by specifying the relative humidity and temperature for the WVTR value. This enables the user to calculate the water-vapor pressure difference. Eor example, the common conditions are 90% relative humidity (rh) at 37.8°C, which means the pressure difference is 5.89 kPa (44 mm Hg). 

Table 2. Water Vapor Transmission Rate Units with Conversion Factors...

A-l Alphabetical Conversion Factors, 416 A-2 Physical Property Conversion Factors, 423 A-3 Synchronous Speeds, 426 A-4 Conversion Factors, 427 A-5 Temperature Conversion, 429 A-6 Altitude and Atmospheric Pressures, 430 A-7 Vapor Pressure Curves, 431 A-8 Pressure Conversion Chart, 432 A-9 Vacuum Conversion, 433 A-10 Decimal and Millimeter Equivalents of Fractions,... 

In this article both unsensitized and mercury vapor sensitized reactions are discussed. The plan has been to proceed from the chemically simplest system, oxygen molecule, to the chemically most complex, ozone plus hydrogen peroxide. Unless otherwise stated, thermochemical values have been taken from compilations of the National Bureau of Standards (68) and are reported in kcal. for the reaction represented in mole amounts. Conversion factors for energy units, spectroscopic notation, and unless noted, spectroscopically based values have been taken from... 

Now, we can use the heat of vaporization as a conversion factor to calculate the energy transferred from the steam as is condenses. The negative sign is included with the heat of vaporization because condensation is an exothermic process. 

Desflurane has a heat of vaporization of 45 cal/g. How much heat does des-flurane absorb from the surroundings when 2 g vaporize To solve this problem, just use the heat of vaporization as a conversion factor. 

Residue Curve Maps for Reactive Mixtures 461 Heat-Exchanger Design 474 Materials of Construction 483 Saturated Steam Properties 487 Vapor Pressure of Some Hydrocarbons 489 Vapor Pressure of Some Organic Components 490 Conversion Factors to SI Units 491... 

B. Suppose that /Jcch for the soil is 200 H20/CO2, that 90% of the water vapor passing out of the canopy comes from the leaves, and that the net photosynthetic rate for the forest (using CO2 from above the canopy as well as from the soil) corresponds to 20 kg of carbohydrate hectare-1 hour-1 (use conversion factor in Table 8-2). If Jm from the soil is 0.6 mmol m-2 s-1, what are the. /Co2 s up from the soil and down into the canopy ... 

Melting point Boiling point Vapor pressure Vapor density Liquid density Conversion factor Odor... 

When setting up your equations, use the correct conversion factors so that you get the desired units when cancehng. But be careful to keep values for vaporization together and separate from those for fusion. Keep track of your units You may have to convert from joules to kilojoules or vice versa. 

It is known that the enthalpy change for the decomposition of X, according to the reaction described above, is -1893 kJ/mol X. The standard enthalpies of formation for gaseous carbon dioxide and liquid water are -393.5 kJ/mol and -286 kJ/mol, respectively. The heat capacity for water is 4.184 J/°C g. The conversion factor between L atm and J can be determined from the two values for the gas constant R, namely, 0.08206 L atm/K mol and 8.3145 J/K mol. The vapor pressure of water at 29.5°C is 31 torn Assume that the heat capacity of the piston-and-cylinder apparatus is negligible and that the piston has negligible mass. 

One conversion factor needed to solve this problem is the molar mass of water. The other conversion factor is given in the problem. It takes 44.0 kJ of energy to vaporize 1 mole of water. 

BS 4370, Part 2, Method 8 is related to ISO 1663. 1981 [25] and describes the determination of water vapor transmission rate (pg/(nr s)), water vapor permeance (ng/(m s Pa)) and water vapor permeability (ng/(m s Pa) for rigid cellular materials that have thicknesses of between 10 mm and 70 mm. The first two properties are specific to the specimen thickness, whereas the permeability is a property of the material if this is homogeneous. A table is included in this British Standard giving conversion factors for all three properties. The method described is suitable for materials having a water vapor transmission rate of between 200 to 3000 pg/(m" . s). 

In order to calculate the vapor pressure on the basis of Eqs. (2) and (3), it is necessary to find a conversion factor K for transforming the relative to the absolute total pressures. This factor may be calculated easily using one of the basic equations for the molecular flow of gases... 

Eq. (2) for the gas phase, but with its chemical potential p,° defined at atmospheric pressure p = 1.0 atm. Equation (3) expresses then the chemical potential of the (pure) solvent vapor over the solution. Note, that in these expressions one always uses atm as unit of pressure, a non-SI unit of pressure (see Fig. 2.3, for conversion factors see Sect 4.5.1). At equilibrium, the two logarithmic terms in Eqs. (1) and (3) must be equal, Pi = pP, and produce Raoult s law. Raoult s law is indicated by the diagonal in the graph of Fig. 7.3. At concentrations approaching the pure solvent, Xj - 1.0, this equation must always hold. 

Conversion factors for ambient air conditions (ppm to mgm ) and for concentrations in blood and other fluids (SI mass to molar units) for a number of volatile compounds are given in Table 6. There may be a big overlap in the blood concentrations of volatile compounds attained after workplace exposure and as a result of deliberate inhalation of vapor. For example, blood toluene concentrations after exposure to up to 127 ppm toluene (UK OEL at the time was 100 ppm) for 8h ranged between 0.4 and... 

The cost of electric power was estimated as the sum of four terms. The first is the cost to provide the steam flow (in pph) noted in Table 4.11. That value was converted to a requirement for energy as 945 BTU/lb steam, and the conversion factor of 3415 BTU/kilowatt (kW). The second term was the power cost to continually operate the air amplifier, taken to be a 6 HP motor. The third term was the power cost to operate a 3 HP water pump for condensed water and solvent vapor fed to the decanter. The fourth term is a general allocation of 52 kW for miscellaneous and unspecified needs. This value was taken from the reference of Appendix A2, Footnote 12, page 34. Both the third and fourth terms were corrected for the actual capacity of activated carbon using the six-tenth power rule used to estimate capital investment. The sum has the units of kW hours. 

We can use the heat of vaporization of a liquid to calculate the amount of heat energy required to vaporize a given amoxmt of that liquid. To do so, we use the heat of vaporization as a conversion factor between moles of the liquid and the amount of heaf required to vaporize it. For example, suppose we want to calculate the amount of heat required to vaporize 25.0 g of water at its boiling point. We begin by sorting the information in the problem statement. 

Body temperamre, ambient pressure,. saturated with water vapor (BTPS) occurs when the person tested exhales a volume of gas at body temperature (37 °C). When collected in the spirometer, this volume rapidly cools to approach the lower ambient temperature and contracts. TTiis reduced volume must be multiplied by the appropriate BTPS conversion factor to correct it to what it should be at normal body temperature (Table 11). 

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