Safe operating limit

Flash points, lower and upper flammability limits, and autoignition temperatures are the three properties used to indicate safe operating limits of temperature when processing organic materials. Prediction methods are somewhat erratic, but, together with comparisons with reliable experimental values for families or similar compounds, they are valuable in setting a conservative value for each of the properties. The DIPPR compilation includes evaluated values for over 1000 common organics. Detailed examples of most of the methods discussed are available in Danner and Daubert."... 

Frequently a piece of equipment is used in different processes during its lifecycle. This could result in process conditions that exceed the safe operating limits of the equipment. Equipment inspection may provide a poor prediction of the equipment s useful life and reliability, due to the change of material handled or change in process chemistry over the life of equipment. Batch operations are also characterized by frequent start-up and shut-down of equipment. This can lead to accelerated equipment aging and may lead to equipment failure. This chapter presents issues and concerns related to the safe design, operation, and maintenance of various pieces of equipment in batch reaction systems, and provides potential solutions. 

Use of materials sensitive to shock, high temperature or high pressure. If the material is inadvertently exposed to an unsuitable condition, or if the process moves out of the safe operating limits, it could result in a loss of containment. 

Explosion testing should be performed to establish safe operating limits. Dust explosibility and ignitability are measurements of the potential for a combustible material, in dust form, to explode or ignite. Any combustible material has the potential to cause a dust explosion if dispersed in air as a dust and ignited. Further details on explosibility testing can be found in Palmer (1973), Bartknecht (1989) and Eckhoff (1997). 

The standard operating procedures demand great attention as they reflect personnel safety issues, safe operating limits and quality considerations. They should be written simply and clearly. The level of detail is determined by the training and experience of the operations staff but should also take into account the hazards inherent in the process. 

If a design limit test is included in the test run (such as a hydrostatic test) and it exceeds safe operating limits, consider writing a special procedure for this part of the test. 

Figure 24.9 Normal characteristics of a generator, illustrating the stability levels (safe operating limits)...

Provide adequate operating instmetions to ensure that the plant is operated within its safe operating limits, and emergeney instmetions. 

It is inherently safer to develop processes with wide safe operating limits that are less sensitive to variations in critical safety operating parameters, as shown in Figure 4.3. Sometimes this type of process is referred to as a forgiving or robust process. If a process must be controlled within a very small temperature band in order to avoid... 

The establishment of safe operating limits on existing plants. 

In a preferred embodiment of the invention, the tubular reaction zone is uncooled and the temperature of the reaction mixture in the tubular reaction zone is controlled within safe operating limits by regulating the temperature... 

The SIS is normally designed to fail-safe on loss of power and takes action only when the process demands that it do so. These demands often occur when safe operating limits are exceeded due to BPCS failures. Therefore, the SIS is designed and managed to be independent of the BPCS in terms of its hardware and software and its user interfaces, such as operator, maintenance, and engineering interfaces. 

Whatever risk reduction methods or technologies are applied, the net result will be a system that must be operated within certain limits. It is essential that safe operating limits be established, documented, and incor-... 

Procedural controls, process controls, 98-99 Process controls, 96-100 active controls, 98 inherently safer approach, 97 mitigation techniques, 99 passive controls, 97-98 procedural controls, 98-99 safe operating limits, 99-100 Process definition, documentation, 102-104 Process design, documentation, 105 Process hazard analysis (PHA) risk assessment, 92-93 screening methods, 63 Process risk management decisions, documentation, 105-106... 

Once a new chemical is introduced into the plant, employees receive on-the-job training on the new production process, which covers safe operating limits, process controls, emergency situations, etc. 

Liquid hydrogen must be stored in highly insulated containers similar to those used for liquefied natural gas. These containers are made from stainless steel and may be spherical or cylindrical in shape. The containers are double-walled to allow use of vacuum insulation in addition to insulation to prevent heat transfer from conduction, convection, and radiative sources. Pressure relief devices are incorporated to release hydrogen should the internal pressure of the tank increase to the maximum safe operating limit. 

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