Loss of control

The subsequent step is to identify the various scenarios which could cause loss of control of the hazard and result in an accident. This is perhaps the most difficult step in the procedure. Many accidents have been the result of improper characterization of the accident scenarios. For a reasonably complex chemical process, there might exist dozens, or even hundreds, of scenarios for each hazard. The essential part of the analysis is to select the scenarios which are deemed credible and worst case. 

Determine Critical Control Points. A critical control point (CCP) is any point in the process where loss of control may result in an unacceptable health risk. A CCP is estabhshed for each identified hazard. The emergence of foodbome pathogens has taught food processors the importance of potential product contamination from the processing environment. 

Often, analysts will want to run special short-term tests with the operating unit in order to identify the cause of the trouble being experienced By the unit. Operators are naturally leery of running tests outside their normal operating experience because their primaiy focus is the stable control of the unit, and tests outside their experience may result in loss of control. Multiple tests with few results may decrease their cooperation. 

Same sensor used for basic process control system and safety instrumented system. Failure of sensor leads to loss of control system and safety system functionality. 

Eailure of basic process control system (BPCS) resulting in loss of control. 

This shows that as the vessel size increases, the volume increases at a faster rate than the surface area. Thus, care must be taken before scale-up is implemented as even a small increase in volume can result in insufficient cooling and subsequent loss of control. 

Creating a strong system that constitutes a passive design requires a complete knowledge and characterization of the potential overpressure scenarios. This requires knowledge of the chemistry outside the design conditions to evaluate effects of loss of utilities and the loss of control systems. 

Chloride leakage with BX softening NOTE Caused by inadequate rinsing. BW carryover Increased BD Temporary loss of control Depassivation... 

Subcase bl This case is encountered, for example, when batch records from different production campaigns are compared and the same number of samples was analyzed in each campaign. (Note under GMP, trend analysis has to be performed regularly to stop a process from slowly, over many batches, drifting into a situation where each parameter on its own is within specifications, but collectively there is the risk of sudden, global loss of control. Catastrophe theory has gained a foothold in physical and biological literature to describe such situations cf. Section 4.14.)... 

Indeed, the resistance problem has sometimes been severe enough to threaten a loss of control over the pest. A study of a number of resistant strains from the field has revealed two major types of resistance mechanism. Some individuals possess aberrant forms of the target site, the Na" channel. At least two forms are known that confer either kdr (<100-fold) or super kdr (>100-fold) resistance, which is the consequence of the presence of insensitive forms of the Na+ channel protein (McCaffery 1998, and Chapter 4, Section 4.4 of this book). 

The main danger in the operation of a nuclear power plant is potential loss of control over the nuclear reaction. If the core overheats, it may either explode or melt down. In either event, radioactive materials escape Irom the reactor to contaminate the environment. Designers attempt to make nuclear reactors fail-safe by providing mechanisms that automatically shut the core down on overheating. One way this has been done is to design the control rods to fall into the core if their control mechanism fails. 

A previously unexplained observation of a link between nose and gonads — the so-called naso-genital relationship — can now be placed in context. Removal of the relay site for the pump-regulator (see above) by extirpation of the sphenopalatine ganglion was found to result in a state of pseudo-pregnancy (Rosen et al, 1940). Interruption of stimulus access would clearly prevent most uptake through loss of control over the pump. A diestrous state would be induced (Sec. 5.3 below) attributable to the lack of male urinary semiochemicals. 

Requires multiple visits each week to the hemodialysis center, which translates into loss of control by the patient. 

Overpressuring of a process or storage vessel caused by loss of control of reactive materials or external heat input... 

In the preparation of 2,5,5-trimethylcyclopenten-3-one by dehydrobromination of the title bromoketone, the scale should be limited to below 10 g of the latter, to avoid a vigorous exotherm and loss of control on addition of the bromoketone to potassium hydroxide in triethylene glycol at 60-70°C. 

Dining the fluorination of organic materials by passing hydrogen fluoride into a vigorously stirred suspension of the oxide (to form transiently mercury difluoride, a powerful fluorinator), it is essential to use adequate and effective cooling below 0°C to prevent loss of control of the reaction system. 

The origin of a malignant tumor is a random genetic mutation leading to the loss of mitotic control by the cells. Normal cells experience mutations regularly, and they are necessary mechanisms of adaptation that are strictly controlled. Malignant transformation, however, means a loss of control and a chaotic, uncontrolled growth. 

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