Volume maximum permissible

Short Term Exposure Limits - Defined as the parts of vapor (gas) per million parts of contaminated air by volume at 25 C (77 °F) and atmospheric pressure. The limits are given in milligrams per cubic meter for chemicals that can form a fine mist or dust. The values are the maximum permissible average exposures for the time periods specified. The term Short Term Exposure Limit, or STEL, is also used and is considered interchangeable with Short Term Inhalation Limit. The STEL designation is derived from the OSHA standards. 

In catalytic incineration, there are limitations concerning the effluent streams to be treated. Waste gases with organic compound contents higher than 20% of LET (lower explosion limit) are not suitable, as the heat content released in the oxidation process increases the catalyst bed temperature above 650 °C. This is normally the maximum permissible temperature to which a catalyst bed can be continuously exposed. The problem is solved by dilution-, this method increases the furnace volume and hence the investment and operation costs. Concentrations between 2% and 20% of LET are optimal, The catalytic incinerator is not recommended without prefiltration for waste gases containing particulate matter or liquids which cannot be vaporized. The waste gas must not contain catalyst poisons, such as phosphorus, arsenic, antimony, lead, zinc, mercury, tin, sulfur, or iron oxide.(see Table 1.3.111... 

Helical-lobe compressors are best suited for base-load applications where they can provide a constant volume and pressure of discharge gas. The only recommended method of volume control is the use of variable-speed motors. With variable-speed drives, capacity variations can be obtained with a proportionate reduction in speed. A 50 per cent speed reduction is the maximum permissible control range. 

When performing chemical reactions it is necessary to consider conceivable deviations (e.g., upsets, abnormal situations, failures) from the normal operation of a process and equipment and their possible effects on the reaction enthalpy AHr, the gas volume M produced and the rate of gas production (dM/dt), the heat flow balance (dQR/dt) - (dQ /dt) and the maximum permissible temperature TeXo for thermal stability under the applicable process conditions. Upsets (abnormal situations, failures) can be divided into two categories, and their consequences can be assessed using the following tables3 ... 

The main contributions are the sample volume and the profile of the injected band characterized by both the injection volume and the injection time 16, 20, 27, 5). We want to calculate the maximum permissible sample size which causes a relative increase in the zone width by a factor 6, hence a decrease in the efficiency by 0. The sensitivity depends little on the column length at constant plate number if the maximum sample size is used in all cases. 

Equations (67) and (68) show that the efficient columns available today tolerate much smaller sample sizes than the columns used a few years ago. Wlicicua lui culuiiiiis With t>p - 25 fiin, h = 5, and /V - 200U tlic maximum permissible sample volume Vs,m is about 60 /xl. tne microparticulate columns can accept samples of only a few microliters without deterioration of the intrinsic column efficiency. 

This problem has been discussed by Snyder (8,10) and Scott 9, II). A general solution is difficult to give since it would depend oh the composition of the sample mixture, e.g., the concentration of the la eluting components, and the detection limit, which varies in liquid chromatography with the chemical nature of the sample component. Therefore some arbitrary assumptions have to be made. From Eq. (26), using the maximum permissible sample size given by Eq. (73), we can write foi the retention volume, Vr, the following expression ... 

Developing, the expression for the maximum permissible sample volume as in chapter (5),... 

The expression for the maximum permissible sample volume, given by equation (20), shows a strong dependence on the product of the solute diffusivity and the viscosity of the mobile phase It is also seen to vary as the inverse of the fourth power of foe-10 so that, for very difficult separations, where (a) is small, the sample volume will be a maximum... 

It Is seen from equation (9) that the maximum sample volume depends on the square of the radius and inversely on the square root of the column inlet pressure. Now, although (r) and (P) are not mathematically interdependent, there is a practical dependance of (r) on (P). The column must, physically, be able to withstand the the pressure (P) and thus, the column walls must be sufficiently thick to accommodate the pressure for any given radius (r). The aspect of column strength, and weight will be discussed further in due course. Now, if the mass of the selected solute that is required per separation is (M) and is placed on the column in the maximum permissible sample volume (Vj),... 

One measure of the hazard associated with this waste is the water dilution volume (m3). The water dilution volume is the volume of water needed to dilute a radionuclide to its maximum permissible concentration in water. A plot of the water dilution volume (WDV) for spent fuel is shown in Figure 16.11. 

The concentration sensitivity of a chromatographic system (XJ is defined as that which will provide a peak with a height equivalent to twice the noise level and can be obtained directly from the system mass sensitivity. If the minimum detectable mass is dissolved in the maximum permissible sample volume [9] (that sample volume that will limit the increase in sample variance to 10% of the column variance), then this solute concentration will constitute the minimum detectable sample concentration. 

It is seen that the system concentration sensitivity is also directly (and solely) dependent on the detector sensitivity and, in contrast to the system mass sensitivity, is independent of column or solute properties. It should be emphasized, however, that in order to realize the minimum concentration sensitivity, the maximum permissible sample volume must be used. 

Now as stated previously, the maximum permissible sample volume (VJ is given by Vj = l.loc... 

Providing the detector has a reasonable sensitivity the limit for (k ), however, is fairly high as shown in table 2 where the sample concentration is assumed to be 0.1 % w/v. The data given above is subject to the caveat that the sample is placed on the column in the maximum permissible volume but not overloaded. 

Figure 3.5 illustrates the spatial variation of power density in one-quarter of the core of a 1060-MWe PWR when the enrichment of and the concentration of boron control poison are uniform throughout the core. The lines plotted are lines of constant power density expressed as kilowatts of heat per liter of reactor volume, and also as kilowatts of heat per foot of fuel rod. The maximum permissible value of the latter is around 16 kW/ft, to ensure against overheating the fuel or cladding. 

This might imply a maximum permissible scale of operation. On the other hand power per unit volume is given by... 

Authors of the report [7.5] have noted, that such lead-bismuth coolant activity gives rise to the problems even under normal operating conditions. They consider that in case of the cover gas leak rate of 0.01% of its volume per day, release of o to the central hall may cause (if gas circuit is not cleaned from polonium) 200 fold exceeding of its maximum permissible concentration (mpc) [7.1]. To ensure that mpc value is not exceeded for personnel in the central hall, it is necessary to comply with very strong requirements for the reactor cover gas circuit leak-tightness. 

Most process plants work in the range of up to 250 bar. Higher pressures are accompanied by higher energies. The characteristic quantity is the product of the maximum permissible pressure (PS) in bar and the volume exposed to it (V) in 1, the energy... 

Furthermore, Eq. (3.57) shows that there is a specific volume due to thermal expansion of the (practically incompressible) liquid which leaves no space for the gaseous phase. This must be accounted for when fixing the maximum permissible degree of filling. Table 3.3 shows some values. ... 

If the maximum permissible Injection volume is defined as the volume at which 80Z of N mCan be retained, then the value in Figure 2 is estimated to be 75 pi and the weight of benzene injected is 0.38 mg. The example of the relationship between N and a constant amount of sample. Injected with different injection volume is illustrated as follows. A Shodex SEC column KF803 is packed with polystyrene gels of a mean particle diameter 6 pm in a 8 mm... 

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