Quantity meters liquids

For liquids, the quantities surface energy and surface tension, usually given the symbol y, are numerically the same and are given in units of millijoules per square meter. Liquid surface energy, or surface tension, is easily observed in that liquids appear to have a skin. Surface energies of common organic liquids vary from about 10 mj /m2 up to about 65 mj /in2 at room temperature. The room-temperature surface energy of water is approximately 72 nij/ni2. 

For the manufacture of SO3 using cold process and manufacture of SO2 using high pressure reactor fed with metered quantities of liquid sulphur and liquid SO3 are economically the most viable options. 

The innovative process as described in Fig. 7.2 is as follows -Metered quantities of liquid SO3, liquid SO2 and liquid ammonia are fed to a high pressure agitated reactor with chilled water cooling. 

For a standard of flow rate metering, traceability is the top priority the measurement uncertainty should he sufficiently small, and a system that features single operation, low measurement uncertainty, and high repeatability is desirable. Therefore, approaches based on weighing are, above all others, favorable candidates for such a purpose. As shown in Fig. 6, a gravimetric primary metering standard has been set up to achieve these requirements [9]. Liquid water is driven by a pneumatic pressure control mechanism to obtain flow rates down to less than a microliter per minute. The measurement capabUity depends on the weighing of the collection beaker, the stability of the pressure difference, the time interval, and the variation of the ambient temperature. Buoyancy variation and liquid evaporation are critical concerns for measurements associated with such a small quantity of liquid. 

In those days, there were no oil refineries, nor bottlers of carbonated soda, nor sulfuric acid plants. There was only one liquid to consider, and move in large quantities. .. fresh water from the mountains. With only one liquid under consideration, fresh water, and no. sophisticated instrumentation, they measured the water s force, or pressure, in terms of elevation. It is for this reason that today all over the world, pump manufacturers u.se the term Head measured in meters or feet of elevation to express pre.ssure or force. The term flow expresses volume over time, such as gallons per minute, or cubic meters per second. 

In automatic systems the filler sets the quantity to be filled on a meter, which closes a valve when this required quantity has been delivered. Overfilling has occurred because the wrong quantity was set on the meter, because there was already some liquid in the tank (left over from the previous load), and because the filling equipment failed. For these reasons many companies now fit their tank trucks with high-level trips, which automatically close a valve in the filling line [8]. 

This equation defines the flow coefficient, Cv. Here, SG is the fluid specific gravity (relative to water), pw is the density of water, and hv is the head loss across the valve. The last form of Eq. (10-29) applies only for units of Q in gpm and hv in ft. Although Eq. (10-29) is similar to the flow equation for flow meters, the flow coefficient Cv is not dimensionless, as are the flow meter discharge coefficient and the loss coefficient (Af), but has dimensions of [L3][L/M]1/2. The value of Cv is thus different for each valve and also varies with the valve opening (or stem travel) for a given valve. Values for the valve Cv are determined by the manufacturer from measurements on each valve type. Because they are not dimensionless, the values will depend upon the specific units used for the quantities in Eq. (10-29). More specifically, the normal engineering (inconsistent) units of Cv are gpm/ (psi)1/2. [If the fluid density were included in Eq. (10-29) instead of SG, the dimensions of Cv would be L2, which follows from the inclusion of the effective valve flow area in the definition of Cv]. The reference fluid for the density is water for liquids and air for gases. 

Boron trifluoride gas may be used in place of the etherate. In this case a fritted-glass gas-dispersion tube that extends below the liquid surface replaces the second addition funnel. Boron trifluoride gas (0.20 mole, 4.48 1.) is passed through the solution as the peroxytrifluoroacetic acid is added. The boron trifluoride may be metered into the mixture through a calibrated flowmeter containing carbon tetrachloride as the indicator liquid. Alternatively, a premeasured quantity of boron trifluoride may be displaced by carbon tetrachloride from a gas bulb. The yield is approximately the same regardless of the source of boron trifluoride. 

Fixed systems are classified in the manner they are stored. Low pressure 2,068 kPa (300 psi) or high pressure 5,860 kPa (850 psi) systems can be specified. Low pressure systems are normally provided when the quantity of agent required exceeds 907 kgs (2,000 lbs ). Protection of electronic or electrical hazards usually requires a design concentration of 50% by volume. NFPA 12 provides a table specifying the exact concentration requirements for specific hazards. As a guide, 0.45 kgs (1 lb.) of CO2 liquid may be considered to produce 0.23 cubic meters (8 cu. ft. ) of free gas at atmospheric pressure. 

Laboratories are normally classified nonhazardous locations if the quantities of flammable and combustible liquids are within the requirements of NFPA. Normally a vapor collection hood is provided when sampling and measurements are conducted with exposed liquids. The primary concern is the exhaust of vapors and the storage and removal material saturated with liquids. The exhaust hood, ducting and a radius of 1.5 meters (5 ft.) from the exhaust vent should be considered an electrically classified area. 

A generally useful method of metering small quantities of compounds with reasonable vapour pressures is to condense the vapour of the compound from a known volume at a known temperature. If the vapour of a liquid or a solid in a reservoir A can expand into an evacuated bulb B of volume V (see Fig. 3.11), then the number n of moles in V is given to an adequate degree of accuracy by the Ideal Gas Law pV = nRT where p is the vapour pressure of the compound at a temperature T which must be lower than the ambient temperature of the vapour (Biddulph and Plesch, 1959). 

Viscosity is equal to the slope of the flow curve, ff = dr/dy. The quantity r/y is the viscosity T for a Newtonian liquid and the apparent viscosity T a for a non-Newtonian liquid. The kinematic viscosity is the viscosity coefficient divided by the density, v = Tf/p. The fluidity is the reciprocal of the viscosity, common units for viscosity, dyne seconds per square centimeter ((dyn-s)/cm2) or grams per centimeter second ((g/(cm-s)), called poise, which is usually expressed as centipoise (cP), have been replaced by the SI units of pascal seconds, ie, Pa-s and mPa-s, where 1 mPa-s = 1 cP. In the same manner the shear stress units of dynes per square centimeter, dyn/cm2, have been replaced by Pascals, where 10 dyn/cm2 = 1 Pa, and newtons per square meter, where 1 N/m2 = 1 Pa. Shear rate is AP//AX, or length/time/length, so that values are given as per second (s 1) in both systems. The SI units for kinematic viscosity are square centimeters per second, cm2/s, ie, Stokes (St), and square millimeters per second, mm2 /s, ie, centistokes (cSt). Information is available for the official Society of Rheology nomenclature and units for a wide range of rheological parameters (11). 

Positive-displacement (PD) flowmeters are used when the total quantity of the flowing process stream is of interest or when a recipe is being formulated in a batch process. These meters operate by trapping a fixed volume of fluid and transferring that volume from the inlet to the outlet side of the meter. The number of such calibrated "packages" of fluid is counted as a measure of total volumetric flow. These measuring devices are used in both gas and liquid services. 

Techniques for handling sodium in commercial-scale applications have improved (5,23,98,101,102). Contamination by sodium oxide is kept at a minimum by completely welded constmction and inert gas-pressured transfers. Residual oxide is removed by cold traps or micrometaUic filters. Special mechanical pumps or leak-free electromagnetic pumps and meters work well with clean liquid sodium. Corrosion of stainless or carbon steel equipment is minknized by keeping the oxide content low. The 8-h TWA PEL and ceiling TLV for sodium or sodium oxide or hydroxide smoke exposure is 2 mg/m. There is no defined AI D for pure sodium, as even the smallest quantity ingested could potentially cause fatal injury. 

A simple apparatus (which can give an accuracy of O-Or) for use with small quantities (0-1 g. or less) of liquid (Fig. 20.VIII J) consists of a small bulb A containing the liquid and wired on to a therino-meter, the bulb being then put into a well-stirred heating bath (Fig. 21.VIIIJ). For higher temperatures (nearly 300°) fused spermaceti is convenient. ... 

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