Measurements volume

For these different methods, the detection is either by volume measurement, gravimetry, conductimetry or coulometry. 

The following diagram represents underground volumes of fluid produced. The relationship between the underground volumes (measured in reservoir barrels) and the volumes at surface conditions is discussed in Section 5.2. The relationships were denoted by... 

Adsorption isotherms conventionally have been determined by means of a vacuum line system whereby pressure-volume measurements are made before and after admitting the adsorbate gas to the sample. For some recent experimental papers, see Refs. 24 and 25. 

As noted above, not all techniques which provide information regarding crystallinity are useful to follow the rate of crystallization. In addition to sufficient sensitivity to monitor small changes, the method must be rapid and suitable for isothermal regulation, quite possibly over a range of different temperatures. Specific volume measurements are especially convenient for this purpose. We shall continue our discussion using specific volume as the experimental method. 

In discussing Fig. 4.1 we noted that the apparent location of Tg is dependent on the time allowed for the specific volume measurements. Volume contractions occur for a long time below Tg The lower the temperature, the longer it takes to reach an equilibrium volume. It is the equilibrium volume which should be used in the representation summarized by Fig. 4.15. In actual practice, what is often done is to allow a convenient and standardized time between changing the temperature and reading the volume. Instead of directly tackling the rate of collapse of free volume, we shall approach this subject empirically, using a property which we have previously described in terms of free volume, namely, viscosity. 

Pressure. Standard atmospheric pressure is defined to be the force exerted by a column of mercury 760-mm high at 0°C. This corresponds to 0.101325 MPa (14.695 psi). Reference or fixed points for pressure caUbration exist and are analogous to the temperature standards cited (23). These points are based on phase changes or resistance jumps in selected materials. For the highest pressures, the most rehable technique is the correlation of the wavelength shift, /SX with pressure of the mby, R, fluorescence line and is determined by simultaneous specific volume measurements on cubic metals... 

Fig 9 3 A simple laboratory set-up for observing the casting process directly. The mould volume measures about 50 X 50 X 6 mm. The walls are cooled by putting the bottom of the block into a dish of liquid nitrogen. The windows are kept free of frost by squirting them with alcohol from a wash bottle every 5 minutes. 

Flow = (iapacity = Q Lit]uid volume measured in gallons per minute (gpm) or liters per minute, cubic meters per hour, or some other rate. 

The previous volume measurement was done by methane because this does not react and does not even adsorb on the catalyst. If it did, the additional adsorbed quantity would make the volume look larger. This is the basis for measurement of chemisorption. In this experiment pure methane flow is replaced (at t = 0) with methane that contains C = Co hydrogen. The hydrogen content of the reactor volume—and with it the discharge hydrogen concentration— increases over time. At time t - t2 the hydrogen concentration is C = C2. The calculation used before will apply here, but the total calculated volume now includes the chemisorbed quantity. 

If the mobile phase is a liquid, and can be considered incompressible, then the volume of the mobile phase eluted from the column, between the injection and the peak maximum, can be easily obtained from the product of the flow rate and the retention time. For more precise measurements, the volume of eluent can be directly measured volumetrically by means of a burette or other suitable volume measuring vessel that is placed at the end of the column. If the mobile phase is compressible, however, the volume of mobile phase that passes through the column, measured at the exit, will no longer represent the true retention volume, as the volume flow will increase continuously along the column as the pressure falls. This problem was solved by James and Martin [3], who derived a correction factor that allowed the actual retention volume to be calculated from the retention volume measured at the column outlet at atmospheric pressure, and a function of the inlet/outlet pressure ratio. This correction factor can be derived as follows. 

Equation (3) merely sums the two peaks to produce a single envelope. Providing retention times can be measured precisely, the data can be used to determine the composition of a mixture of two substances that, although having finite retention differences, are eluted as a single peak. This can be achieved, providing the standard deviation of the measured retention time is small compared with the difference in retention times of the two solutes. Now, there is a direct relationship between retention volume measured in plate volumes and the equivalent times, which is depicted in Figure 6. 

Liquids have relatively low compressibility compared with gases and, thus, the mobile phase velocity is sensibly constant throughout the column. As a consequence, elution volumes measured at the column exit can be used to obtain retention volume data and, unless extreme accuracy is required for special applications, there is no need for the retention volume to be corrected for pressure effects. 

The compressibilities of solvents vary significantly from one solvent to another. The compressibility of cyclohexane is about 0.67% per thousand p.s.i. change in pressure [11] and, thus, for a column operated at 6,000 p.s.i. (mean pressure 3,000 p.s.i.), there will be an error in retention volume measurement of about 2%. In a similar manner, n-heptane has a compressibility of about 1.0% per 1,000 p.s.i. change in pressure [11] and, under similar circumstances, would give an error of about 3% in retention volume measurement. Fortunately, as already discussed in Part 1 of this book, there are other retention parameters that can be used for solute... 

Calibrate the detector tube pump for proper volume measurement at least quarterly. Simply connect the pump directly to the bubble meter with a detector mbe in-line. Use a detector mbe and pump from the same manufacturer. Wet the inside of the 100 cc bubble meter with soap solution. For volume calibration, experiment to get the soap bubble even with the zero ml mark of the buret. For piston-type pumps, pull the pump handle all the way out (full pump stroke) and note where the soap bubble stops for bellows-type pumps, compress the bellows fully for automatic pumps, program the pump to take a full pump stroke. 

For gaseous feeds, space velocity SV is normally determined in terms of volumes measured at standard conditions T = 25°C and P = 1.013 bar. 

FIGURE 5,20 Graphical representation depicting relationship between airway volume measurements. The curve represents both tidal and forced breathing patterns. 

Ratio between the volumes, measured at standard conditions, of the gas and oil produced simultaneously (units m /m or cu.ft./barrel). The English acronym GOR is also used in France. 

Anyone making a measurement has a responsibility to indicate the uncertainty associated with it. Such information is vital to someone who wants to repeat the experiment or judge its precision. The three volume measurements referred to earlier could be reported as... 

What happens to a gas as the temperature is changed An experiment provides the answer. Table 4-1 shows some pressure-volume measure-... 

More accurate pressure-volume measurements extending to much higher pressures have been performed. Table 4-IV shows the resulis of such experiments. 

ACCURATE PRESSURE-VOLUME MEASUREMENTS FOR 17.00 GRAMS OF AMMONIA GAS AT 25°C... 

The following reaction is carried out with all gas volumes measured at the same pressure and temperature ... 

A new, simple, and practical method for pore volume measurement was proposed... 

Figure 18. Procedure for EPV (effective pore volume) measurement (a) a 50 g MnO, sample is placed in a 100 mL graduated cylinder (2) water is added gradually in 0.5 mL portions (3) with a stopper in place, the cylinder is turned upside down 10 times while being shaken (4) the cylinder is droppes 4 cm onto a wooden surface (5) the Mn02 sample volume is read after 5 and 10 taps (i.e., drops).

A volume measure of the permitted flow rate of water through ion exchange resins and sometimes other media, such as sand. Typically, ion-exchange resins used for water softening will tolerate 8 to 40 BV/hr. 

In some cases, (Ve) may be sufficiently small to be ignored, but for accurate measurements of retention volume, and particularly capacity ratios, the actual volume measured should always be corrected for the extra column volume of the system and equation (11) should be put in the form... 

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