Percentages

We often use percentages to describe quantitatively how a total is made up of its parts. In Table 1 -4, we described the amounts of elements present in terms of the percentage of each element. Percentages can be treated as unit factors. For any mixture containing substance A, 

If we say that a sample is 24.4% carbon by mass, we mean that out of every 100 parts (exactly) by mass of sample, 24.4 parts by mass are carbon. This relationship can be represented by whichever of the two unit factors we find useful  

This ratio can be expressed in terms of grams of carbon for every 100 grams of sample, pounds of carbon for every 100 pounds of sample, or any other mass or weight unit. The next example illustrates the use of dimensional analysis involving percentage. 

pennies made since 1982 consist of 97.6% zinc and 2.4% copper. The mass of a particular penny is measured to be 1.494 grams. How many grams of zinc does this penny contain  

From the percentage information given, we may write the required unit factor 

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These sources of waste from the steam system can be reduced by increasing the percentage of condensate returned (in addition to reducing steam generation by increased heat recovery). 

The percentage humidity is the ratio of the amount of water vapour present per unit mass of dry air to the amount the air could hold if... 

With the accumulation of results obtained from various and complex analyses of narrow cuts (Waterman method), correlations have been found f ctween refractive index, specific gravity and molecular weight on one hand, and percentages of paraffinic, naphthenic and aromatic carbon on the other. 

The naphthenic carbon percentage is the difference between 100 and the sum of the above concentrations. 

Starting from these methods, as we will see further on, nuclear magnetic resonance (NMR) of carbon has provided an absolute percentage of aromatic, paraffinic, and naphthenic carbons. 

Comparing the overall concentrations of these different carbons designated generally as structural patterns , measured before and after a process such as FCC or hydrocracking (see Chapter 10), enables the conversion to be monitored the simple knowledge of the percentage of condensed aromatic carbon of a feedstock gives an indication of its tendency to form coke. 

As stated earlier, these hydrocarbons are difficult to quantify with accuracy. The FIA method, which is a chromatographic adsorption on silica, gives volume percentages of saturated hydrocarbons, olefins and aromatics. 

The level of injector fouling is most often illustrated in terms of residual flow (RF) expressed as a percentage of the flow under new conditions for a given needle lift. An RF on the order of 20% for a lift of 0.1 mm is a good compromise. This level may not be achieved with certain aromatic or naphthenic diesel fuels. The best recourse is then detergent additive addition. 

The initial temperature of a gas condensate lies between the critical temperature and the cricondotherm. The fluid therefore exists at initial conditions in the reservoir as a gas, but on pressure depletion the dew point line is reached, at which point liquids condense in the reservoir. As can be seen from Figure 5.22, the volume percentage of liquids is low, typically insufficient for the saturation of the liquid in the pore space to reach the critical saturation beyond which the liquid phase becomes mobile. These... 

Black oils are a common category of reservoir fluids, and are similar to volatile oils in behaviour, except that they contain a lower fraction of volatile components and therefore require a much larger pressure drop below the bubble point before significant volumes of gas are released from solution. This is reflected by the position of the iso-vol lines in the phase diagram, where the lines of low liquid percentage are grouped around the dew point line. 

The percentages chosen are often denoted as the p85, p50, pi 5 values. Because they each approximately represent one third of the distribution, their discrete probabilities may each be assigned as one third. This approximation is true for a normal (or symmetrical) PDF. 

When estimating the operating and maintenance costs for various options, it is recommended that the actual activities which are anticipated are specified and costed. This will run into the detail of frequency and duration of maintenance activities such as inspection, overhaul, painting. This technique allows a much more realistic estimate of opex to be made, rather than relying on the traditional method of estimating opex based on a percentage of capex. The benefits of this activity based costing are further discussed in Section 13.0 and 14.0. 

The resource loading can be represented in percentage terms (see Figure 12.7) to give an indication of the resource weighting distribution on a daily basis and per activity. (Note Activity B has been moved to day 3 to smooth resource loading.)... 

Cost Plus Profit contract all costs incurred by the contractor are reimbursed in full, and the contractor then adds an agreed percentage as a profit fee. 

Fixed opex is proportional to the capital cost of the items to be operated and is therefore based on a percentage of the cumulative capex. Variable opex is proportional to the throughput and is therefore related to the production rate (oil or gross liquids). Hence,... 

Royalty is normally charged as a percentage of the gross revenues from the sale of hydrocarbons, and may be paid in cash or in kind (e.g. oil). The prevailing oil price is used. 

Each year the capital allowance is a fixed percentage of the unrecovered value of the asset at the end of the previous year. The same comments about when the allowance can start apply. 

Many variations on the above theme exist, and the percentage shares A/ill vary from country to country and from contract to contract. 

In Section 13.2, it was suggested that opex is estimated at the development planning stage based upon a percentage of cumulafive capex (fixed opex) plus a cosf per barrel of hydrocarbon production (variable opex). This method has been widely applied, with the percentages and cost per barrel values based on previous experience in the area. One obvious flaw in this method is that as oil production declines, so does the estimate of opex, which is nof the common experience as equipment ages it requires more maintenance and breaks down more frequently. 

A considerable percentage (40% - 85%) of hydrocarbons are typically not recovered through primary drive mechanisms, or by common supplementary recovery methods such as water flood and gas injection. This is particularly true of oil fields. Part of the oil that remains after primary development is recoverable through enhanced oil recovery (EOR) methods and can potentially slow down the decline period. Unfortunately the cost per barrel of most EOR methods is considerably higher than the cost of conventional recovery techniques, so the application of EOR is generally much more sensitive to oil price. 

For detecting and percentage evaluation of the participation of the amount of austenite in the quenched structure of hyper-eutectoidal steel, devices manufactured by CMP type WIROTEST 202 and WIROTEST 12 finish (Table 1.) are applied. These devices allow to detea and evaluate the content of residual austenite as well as form the signal for part segregation with austenite content above the allowed amount, as well as parts with grinding burning... 

The percentage share of the inserts made austenite steel in the martensite structure is refered to the visual field of the probe in the given location. Every probe after performance is given a characteristics, in which the visual field is given, determined using special devices defining the visual field at different distances from the tested object. 

Segregation of bearings, with regard to residual austenite was performed with the aid of WIROTEST 202 and WIROTEST 12 finish. Selected rings with defined indications were subject to metalographic tests, in order to state whether residual austenite occurs, and then using the diffraction method, the percentage content of residual austenite. 

The realized experiments have shown the large possibilities of analysis by the eddy currents method. They allow, besides the verification of the coating and the determination of its thickness, to give an overview on the percentage of the main chemical components of the controlled samples coating by a deepened processing. 

Evaluation data taken from the more than 8 thousand reports of the laboratory and field wire ropes inspections show that the visual methods and life time criteria are non adequate to real durability of the ropes in service [4]. The data show that only a very small percentage of all ropes was replaced in a proper time, when one has used a visual inspection. 

The total budget proposed is ECU 16.3 billion, which is a 3% increase in the percentage of the EU s GDP represented by the new Framework Programme compared to the previous one. 

A large percentage of eddy-current inspections are conducted in the field, away from the home base and often in remote or inaccessible locations. Using local telephone lines or mobile phone lines would allow the inspector to beam his data back to the office. In this way highly qualified personnel can be consulted when problems or difficult to interpret results occur. Inspectors no longer need to feel isolated on site. 

A gas/gas heat exchanger at a refinery had a known leakage, which it for technical reasons had been impossible to repair completely. The objective of the survey was to determine the leakage size in terms of the percentage of process stream crossing it. 

Many solids show marked swelling as a result of the uptake of a gas or a liquid. In certain cases involving the adsorption of a vapor by a porous solid, a linear relationship exists between the percentage of linear expansion of Ae solid and the film pressure of the adsorbed material [134, 135]. 

An enlarged view of a crystal is shown in Fig. VII-11 assume for simplicity that the crystal is two-dimensional. Assuming equilibrium shape, calculate 711 if 710 is 275 dyn/cm. Crystal habit may be changed by selective adsorption. What percentage of reduction in the value of 710 must be effected (by, say, dye adsorption selective to the face) in order that the equilibrium crystal exhibit only (10) faces Show your calculation. 

Calculate the percentage of atoms that would be surface atoms in a particle containing 125 atoms 1000 atoms. Assume simple cubic geometry. 

Most metal surfaces have the same atomic structure as in the bulk, except that the interlayer spaciugs of the outenuost few atomic layers differ from the bulk values. In other words, entire atomic layers are shifted as a whole in a direction perpendicular to the surface. This is called relaxation, and it can be either inward or outward. Relaxation is usually reported as a percentage of the value of the bulk interlayer spacing. Relaxation does not affect the two-dimensional surface unit cell synuuetry, so surfaces that are purely relaxed have (1 x 1) synuuetry. 

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