Safety aspects

Safety aspects for two different situations are considered. The first is for nominal operating conditions, where the objective is to maintain stable control of the reactor temperature. The second is for deviations of these operating conditions, especially in the case of a cooling failure, where the objective is to design a reactor that behaves safely even under adiabatic conditions. 

Handling biological material always raises the issue of safety for the persoimel involved. Chemical hazards and safety procedures relating to these are well known for chemists. Regarding biological hazards, first the staff participating in the research should be aware of them, and second, adequate precautions should be taken and the personnel should be trained on how to handle human samples safely. 

Laboratory persoimel should avoid any direct contact of skin and mucous membranes with the human specimens including blood or blood products, excretions, secretions, tissues, or other biological materials. Note that most accidental personnel 

Use of chemicals is highly restricted hazardons chemicals cannot he nsed or stored. Low risk of exposure due to the strong restriction for using hazardous chemicals. 

Use and storage of hazardous chemicals is restricted. Moderate risk of exposure, controlled by limiting the use of hazardous chemicals. 

Use of chemicals is generally unrestricted the use of hazardous chemicals is restricted to closed environment. Substantial risk of exposure, controlled by stringent engineering controls, by minimizing the use and storage of hazardous chemicals, and by carefully reviewing work practices. 

The catalytic hydrogenation of aromatic nitro compounds is a potentially hazardous reaction. The safety of a specific operation depends both on the nature of the nitro arene and on the operating conditions [14], 

Hydrogen-air mixtures are explosive over a wide range of concentrations (4-75 %, v/v) and have a very low ignition energy (0.02 mJ). 

Dry hydrogenation catalysts such as Raney nickel and palladium or platinum on charcoal are pyrophoric. One safety measure is the use of wet catalysts this is usually no problem because the hydrogenation reaction produces water. 

The reduction of nitroaromatic compounds is a very exothermic reaction (560 kJ mol ). When reaction control is lost, decomposition of the aromatic nitro compound or of partially hydrogenated intermediates could be triggered easily. 

Hazards Resulting from the High Decomposition Energy of Aromatic Nitro Compounds and Some Intermediates 

Problematic Chemicals Environmental, Health and Safety Aspects (EHS) 

All routes required highly flammable or hazardous substances such as cyclohexane (A), methanol (A-C), toluene (C, D), diisopropyl ether (D), sodium ethoxide 

All routes used toxic substances such as methanol, acetic acid (D), oxalic acid ethyl ester (A-D), cyclohexane (A), toluene, sulfuric acid and hydrochloric acid. Overall, no major differences were observed with the exception of viologen used in A This substance is toxic to fish, meaning that the sewage of A has to be processed in a water treatment plant, which is not necessary in B. 

The most dangerous substance with regard to the water hazard was toluene (C and D). All other substances only have a low water hazard potential. The potential for eutrophication was only given in A and B where phosphates were used. Persistent and accumulating substances were not used in any of the routes. 

All scientific studies involve some aspect of practical work. It is therefore essential to be able to observe and to record information accurately. In the context of environmental analyses, it should be borne in mind that not all practical work is carried out in the laboratory. Indeed it could be argued that the most important aspects of the whole practical programme are done outside the laboratory in the field, as this is the place where the actual sampling of environmental matrices (air, water, soil, etc.) takes place. It is still common practice, however, to transport the acquired sample back to the laboratory for analysis, so knowledge and implementation of the storage conditions and containers to be used are important. Both sampling and sample storage are covered in Chapters 3 and 4, respectively. 

No laboratory work should be carried out without due regard to safety, both for yourself and for the people around you. While the Health and Safety at Work 

Act (1974) provides the main framework for health and safety, it is the Control of Substances Hazardous to Health (COSHH) regulations of 1994 and 1996 that impose strict legal requirements for risk assessment wherever chemicals are used. Within this context, the use of the terms hazard and risk are very important. A hazardous substance is one that has the ability to cause harm, whereas risk is about the likelihood that the substance may cause harm. Risk is often associated with the quantity of material being used. For example, a large volume of a flammable substance obviously poses a greater risk than a very small quantity. Your laboratory will operate its own safety scheme, so ensure that you are aware of what it is and follow it. 

The basic rules for laboratory work (and, as appropriate, for associated work outside the laboratory using chemicals) are as follows  

What is one of the first things that you should consider before starting a laboratory experiment  

As described above, the main route to adipic acid involves the formation of AMNA. Laboratory studies have determined the heat of the reaction at each individual step. 

Under normal plant operating conditions, heat release is determined by the cyclo-hexanol/cyclohexanone mix flow, which is instrument-controlled in order to keep the correct mix-to-nitiic acid ratio. By cutting off the KA oil feed, the reaction stops and heat release ceases. In most industrial reactors, the water cooling system inside the reactor is regulated by the temperature of the reaction mix. Redimdant alarms and emergency stops are installed to automatically cut off the flow of the cyclo-hexanol/cyclohexanone mix in case of a malfunction. Some of the conditions and chains of events that could lead to potentially dangerous situations include  

In order to prevent these conditions from occurring, redundant alarm and emergency systems are installed. If the temperature falls below 65°C or rises above certain safety limits, or in the case of a lack of air for instruments, the emergency safety system will cut off the reactant feed to the reactor, thus removing the cause of the 

It should be noted that carbide precipitation depends upon carbon content, temperature and the length of time at that temperature. The most critical temperature range is around 700 C, at which 0.06% carbon steels will precipitate carbides in about 2 minutes, whereas 0.02% carbon steels are effectively immune from this problem. 

It is possible to reclaim steel which suffers from carbide precipitation by heating it above 1,000 C, followed by water quenching to retain the carbon and chromium in solution and so prevent the formation of carbides. Most structures which are 

Therefore, the following measures for the safe operation of air separation plants should be observed  

In order to avoid exceeding a certain enrichment in an ASU, in places with the highest enrichment, i.e. mostly in the sump of the low-pressure column (upper column) or after a falling film evaporator, a certain quantity of LOX per time tmit is discharged. In order not to exceed arithmetically an enrichment of 1000, for example, 0.5% of the generated hquid oxygen have to be extracted continuously. To avoid product losses, this liquid is discontinuously being flushed into the warm 02-product pipe. 

The advantage of a vacuum-operated plant is the fact that the evaporation will stop immediately if the vacuum is interrupted. In case of faults, a safe operation can be established immediately. 

This is not the case in pressure-operated plants. A pressure-less operating mode can only be achieved if heat in form of flash vapour and product is discharged and 

Blowing off of the safety valves can result in predictable faults. These faults can be avoided by setting up an emergency condensation. 

The pressure evaporation will represent a problem in case of unpredictable faults, such as leaks for which a directed discharge is not possible. If hazardous substances are processed, a pressure evaporation can therefore not be used. 

Although appropriate sensors are built to withstand the appUed pressures, it is advisable to consider additional protective measures to avert potential danger resulting from smaller parts being ejected in the case of faults. This can be achieved 

13) Picture of ruptured steam engine boiler, public domain, taken from www.wikipedia.org. 

14) Directive lEC/EN 62061 Safety of machinery - Functional safety of safety-related electrical, electronic, and programmable electronic control systems. 

With the knowledge that material tensile strength declines with rising temperature (especially in the range above 200 °C), it is obvious that reliable temperature detection is also a safety issue in high-pressure technology. 

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Wells are worked over to increase production, reduce operating cost or reinstate their technical integrity. In terms of economics alone (neglecting safety aspects) a workover can be justified if the net present value of the workover activity is positive (and assuming no other constraints exist). The appropriate discount rate is the company s cost of capital. 

Each of the main facility types, e.g. steel jacket, gravity structure, tension leg and floating platform, have different options for decommissioning. The main factors which need to be considered and which will impact on costs are type of construction, size, distance from shore, weather conditions and the complexity of the removal, including all safety aspects. The following options are available ... 

A fatal accident and some other disasters, which were caused by small cracks, lead to a more strict consideration of the security of these steam drums. Parallel to these the economical pressure, due to the globalisation of the today s industry, lead to the increase of the pressure and the rotation speed of the paper production machines for a higher output of the production, which means, that all safety aspects from the design and the material will be exploited totally. On the other hand cast iron is also not a ductile and comfortable material, like the most steels for the pressure equipment. 

Certain types of equipment are specifically excluded from the scope of the directive. It is self-evident that equipment which is already regulated at Union level with respect to the pressure risk by other directives had to be excluded. That is the case with simple pressure vessels, transportable pressure equipment, aerosols and motor vehicles. Other equipment, such as carbonated drink containers or radiators and piping for hot water systems are excluded from the scope because of the limited risk involved. Also excluded are products which are subject to a minor pressure risk which are covered by the directives on machinery, lifts, low voltage, medical devices, gas appliances and on explosive atmospheres. A further and last group of exclusions refers to equipment which presents a significant pressure risk, but for which neither the free circulation aspect nor the safety aspect necessitated their inclusion. 

The current or potential iadustrial appHcations of microemulsions iaclude metal working, catalysis, advanced ceramics processiag, production of nanostmctured materials (see Nanotechnology), dyeiag, agrochemicals, cosmetics, foods, pharmaceuticals, and biotechnology (9,12—18). Environmental and human-safety aspects of surfactants have begun to receive considerable attention (19—21). 

Specifications, Standards, Quality Control and Health and Safety Aspects. The OSB industry is represented by the APA—The... 

Health and Safety Aspects. The U.S. EPA has significantly reduced the aHowed levels of antimony compounds in drinking water causing a toxicity cloud over the viabHity of this class of stabilizers. Presently, antimony products are no longer aHowed for use as potable water pipe stabilizers pending completion of NSE International s review (28). Eor these reasons, the future of this stabilizer technology appears limited. 

The safety aspects of pdot-plant constmction and operation will continue to grow driven by both regulation and an increased awareness of the potential hazards. This will also require specialized skills and training at ad. levels. 

Health nd Safety Factors. Thionyl chloride is a reactive acid chloride which can cause severe bums to the skin and eyes and acute respiratory tract injury upon vapor inhalation. The hydrolysis products, ie, hydrogen chloride and sulfur dioxide, are beheved to be the primary irritants. Depending on the extent of inhalation exposure, symptoms can range from coughing to pulmonary edema (182). The LC q (rat, inhalation) is 500 ppm (1 h), the DOT label is Corrosive, Poison, and the OSHA PEL is 1 ppm (183). The safety aspects of lithium batteries (qv) containing thionyl chloride have been reviewed (184,185). 

The following discussion on health and safety aspects of titanium compounds is concerned only with the behavior of the titanium present in inorganic compounds and not with the effects of the compounds themselves. For example, titanium tetrachloride must be treated with care because of the effects of the hydrochloric acid and heat produced when it reacts with water, not because of the possible toxicity of titanium. Apart from very few exceptions, the inorganic compounds of titanium are generally regarded as having low toxicity. Because of the ubiquitous nature of the element and its compounds, average concentrations of titanium in blood have been determined at 130—160 Fg/L (182—184), with a typical value of 10 Fg/L in urine (185). 

The lower volatihty of JP-8 is a significant factor in the U.S. Air Force conversion from JP-4, since fires and explosions under both combat and ordinary handling conditions have been attributed to the use of JP-4. In examining the safety aspects of fuel usage in aircraft, a definitive study (15) of the accident record of commercial and military jet transports concluded that kerosene-type fuel is safer than wide-cut fuel with respect to survival in crashes, in-flight fires, and ground fueling accidents. However, the difference in the overall accident record is small because most accidents are not fuel-related. 

Additional information on health and safety aspects should be sought by consulting material safety data sheets available from suppHers of the chemical in question. In addition, most suppHers of bleaching chemicals, upon request, provide on-site training sessions by experts on the safe use and handling of their products. 

There were over 3000 electrostatic powder spray lines and about 800 other powder coating installations operating in the United States as of 1991. Eor additional general information on the safety aspects of powder coatings, see References 90, 93, and 94. 

General Safety Aspects. Whereas cyanides have become infamous as poisons in part because of the use in prison execution chambers, Na2i death camps, and in over-the-counter dmg tampering cases, there is worldwide safe production of nearly one million t annually. 

Table A.4 Essential Questions on Safety Aspects of Reactions...

Once a toller has been selected and any required preliminary confidentiality protection is in place, the client typically shares more detailed information. The toller can then make an informed decision about the economic, technical, and safety aspects involved in bidding the work. If the two parties decide the project will be mutually beneficial, agreements and obligations are negotiated and then formalized in a written contract. Both parties—the client and the toller—have roles in fulfilling the contract and in carrying out their responsibilities to the workers and the public. The purpose of the written contract is to clarify and document those roles and responsibilities to effectively execute, maintain and eventually terminate the project. 

In order to quantify the sometimes intangible elements of variability associated with the product design and the safety aspects in service requires an understanding of risk . The assessment of risk in terms of general engineering practice will be discussed next. This will lead to a better understanding of designing for quality and reliability, which is the main focus of the book. 

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