Limitation of effects

Limitation of Effects of Failures Limitation can be done by equipment design or change in reaction conditions, rather than by adding on protective equipment. For example ... 

Moderate Use less hazardous conditions, a less hazardous form of a material, or facilities which minimize the impact of a release of hazardous material or energy (also called Attenuation and Limitation of Effects). 

Moderate (attenuation and limitation of effects) Use vacuum to reduce boiling point Reduce process temperatures and pressures Refrigerate storage vessels Dissolve hazardous material in safe solvent Operate at conditions where reactor runaway is not possible Place control rooms away from operations Separate pump rooms from other rooms Acoustically insulate noisy lines and equipment Barricade control rooms and tanks... 

The approximate pH range over which a buffer solution remains effective can be deduced from Figure 3.1. The limits of effective buffering can be seen as the points at which the ratio [AH]/[A ] becomes 10 1 or 1 10 whence substitution in equation (3.20) yields... 

In practice the main purpose of the process plant design is to minimize the total process risk for the limitation of effects. Here risk is the product of the probability of an incident to happen and the possible consequences of that incident. In this thesis the limitation of effects by the means of inherent safety principles is evaluated. 

If it is not possible to make plants safer by intensification, substitution or attenuation, the effects of a failure should be limited. For instance equipment is designed so that it can leak only at a low rate that is easy to stop or control. For example gaskets should be chosen to minimize leak rates. Also limitation of effects should be done by equipment design or change in reaction conditions rather than by adding on protective equipment. 

Limitation of effects By equipment design By changing reaction conditions X X X... 

From Table 6 it can be seen how the selected parameters have a connection to the basic principles of inherent safety. For instance the subindices of equipment safety and safe process structure contain several characteristics of inherent safety such as limitation of effects or tolerance to maloperation. It is practical to include several characteristics into few parameters, since the inherent safety principles are both very broad and overlapping. The philosophy behind them cannot be described just by one process parameter. The selected parameters are discussed in more detail on the following pages. 

Limitation of Effects - safer technical alternatives - safer reaction conditions temperature pressure equipment safety safe process structure pressure temperature chemical interaction... 

If each cell responds to radiation autonomously (i.e., independently of any other cell), an upper limit of effect probability E D) is the probability that at least one energy deposition event actually occurred in it. This latter is given [by Poisson statistics, see Eqs. (13) and (14)] by 1—exp(—Z)/zf) and thus, for any dose, one must have ... 

However, about 200 years ago, Thenard and Gay-Lussac were the pioneers who decided to concentrate an HF solution and to study the very specific characteristics of both its physical and its chemical properties. They have noticed that the use of a solution of diluted potash could stop both pains and burns caused by HF. Why was this brand-new concept abandoned so quickly Is the exothermic characteristic of the reaction the only cause of this abandon and is it only a myth The limit of effectiveness of passive washing is probably the principal explanation. 

The analysis of the potential consequences of an accident is a useful way of understanding the relative inherent safety of process alternatives. These consequences might consider, for example, the distance to a benchmark level of damage resulting from a fire, explosion, or toxic material release. Accident consequence analysis is of particular value in understanding the benefits of minimization, moderation, and limitation of effects. This discussion includes several examples of the use of potential accident consequence analysis as a way of measuring inherent safety, such as the BLEVE and toxic gas plume model results shown in Figures 4, 5, and 6. 

The approximate pH range over which a buffer solution remains effective can be deduced from figure 3.1. The limits of effective buffering can be seen... 

In dtphvuylryanarfdne, we have the extreme limit of effectiveness in low concentrations of all chemical agents used in the war. Thus, a con-(tentration of 0.00025 mg. per lit[Pg.233]

I Scattered pinpoint and cloudy-white frosting signal the most superficial peel to the dermis this is the limit of effectiveness (see Chapter 15). 

While a 97% decrease in required column efficiency is calculated for changing k from 0.1 to 1.0, another 70% decrease occurs for a k change from 1.0 to 10.0. It is clear from Eq. (21) that as k becomes large, the resolution is unaffected by small changes in k. Changing k to improve resolution thus has an upper limit of effectiveness at approximately k = 10. This is illustrated in Fig. 8. 

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