Understanding Hazards

Regardless of the regulatory definitions of hazard, understanding chemical characteristics that pose potential hazards should be a fundamental part of the education and training of any laboratory worker. These characteristics may be derived from knowledge of the properties and/or precursors of the waste. The characteristics may also be established by specific tests cited in the regulations. 

HO DECIDES what s safe And how do they make that determination Another principle of safety is assessing the risks of hazards. Understanding how we each view risk affects how we behave in the laboratory, and affects how we interpret safety information. Not everyone makes the same choice given a set of dangers and options. This chapter is about the process of risk assessment and the means by which scientists share information about hazard levels posed by chemicals. Students involved in research projects have to learn to develop their sense of judgment about risk as they plan and conduct experiments. Will you know how to decide what s safe when presented with the design of a new experiment ... 

When developing responsibilities for nonsupervisory employees, do not confuse specific responsibilities with work rules and/or work practices. A short statement about the employee s responsibility to report hazards, understand and follow rules, and work practices is applicable may include ... 

A knowledge of the molecular composition of a petroleum also allows environmentalists to consider the biological impact of environmental exposure. Increasingly, petroleum is being produced in and transported from remote areas of the world to refineries located closer to markets. Although only a minuscule fraction of that oil is released into the environment, the sheer volume involved has the potential for environmental damage. Molecular composition can not only identify the sources of contamination but also aids in understanding the fate and effects of the potentially hazardous components (7). 

Definition of Terms Following are some definitions that are useful in understanding the components of hazards and risk (CPQRA, 1989, pp. 3, 4). 

Understanding the Reactive Chemicals and Reactive Chemicals Systems Involved The main business of most chemical companies is to manufacture products through the control of reactive chemicals. The reactivity that makes chemicals useful can also make them hazardous. Therefore, it is essential that people who design or operate chemical processes understand the nature of the reactive chemicals involved. 

Example The combustion process in large vapor clouds is not known completely and studies are in progress to improve understanding of this important subject. Special study is usually needed to assess the hazard of a large vapor release or to investigate a UVCE. The TNT equivalent method is used in this example other methods have been proposed. Whatever the method used for dispersion and pressure development, a check should be made to determine if any govern-mentaf unit requires a specific type of analysis. 

The selection of materials to be used in design dictates a basic understanding of the behavior of materials and the principles that govern such behavior. If proper design of suitable materials of construction is incorporated, the eqiiipment should deteriorate at a uniform and anticipated gradual rate, which will allow scheduled maintenance or replacement at regular inteivals. If localized forms of corrosion are characteristic of the combination of materials and environment, the materials engineer should still be able to predict the probable life of equipment, or devise an appropriate inspection schedule to preclude unexpected failures. The concepts of predictive, or at least preventive, maintenance are minimum requirements to proper materials selection. This approach to maintenance is certainly intended to minimize the possibility of unscheduled production shutdowns because of corrosion failures, with their attendant possible financial losses, hazard to personnel and equipment, and resultant environmental pollution. 

Ronald E. Hester is Professor of Chemistry in the University of York. He was for short periods a research fellow in Cambridge and an assistant professor at Cornell before being appointed to a lectureship in chemistry in York in 1965. He has been a full professor in York since 1983. His more than 300 publications are mainly in the area of vibrational spectroscopy, latterly focusing on time-resolved studies of photoreaction intermediates and on biomolecular systems in solution. He is active in environmental chemistry and is a founder member and former chairman of the Environment Group of the Royal Society of Chemistry and editor of Industry and the Environment in Perspective (RSC, 1983) and Understanding Our Environment (RSC, 1986). As a member of the Council of the UK Science and Engineering Research Council and several of its sub-committees, panels and boards, he has been heavily involved in national science policy and administration. He was, from 1991-93, a member of the UK Department of the Environment Advisory Committee on Hazardous Substances and is currently a member of the Publications and Information Board of the Royal Society of Chemistry. 

Understanding the chemistry of the process also provides the greatest opportunity in applying the principles of inherent safety at the chemical synthesis stage. Process chemistry greatly determines the potential impact of the processing facility on people and the environment. It also determines such important safety variables as inventory, ancillary unit operations, by-product disposal, etc. Creative design and selection of process chemistry can result in the use of inherently safer chemicals, a reduction in the inventories of hazardous chemicals and/or a minimization of waste treatment requirements. 

Characterizing chemicai reactivity hazards invoives a review of the inherent thermai hazards of the pure process materiais as weii as the thermai hazards of the materiais under processing conditions. Gaining this understanding and characterizing thermaiiy hazardous systems is a muitistep process. 

The first step is to understand the context in which the thermai hazard information is needed. This might inciude information on materiais, reactions, processing conditions, previous incidents, if any, and any other avaiiabie information that can heip with the characterization. 

After understanding the probiem, the second step is to conduct a theoreticai screening to determine the expected thermai hazards of a system. Tabie A.l identifies properties of materiais to be considered, and some potentiai sources of information, in formuiating an opinion about the thermai hazards of particuiar materiais and reactions. 

While these responsibilities seem straightforward, there are numerous responsibilities that are intertwined and discrete. Both parties need to understand their individual responsibilities especially regarding process hazards, environmental concerns, communication, and technology/knowledge transfer. 

In order to understand the chemical and process hazards, a Process Hazard Analysis (PHA) should be conducted. For tolls involving... 

Is there potential that the product may result m the environmental or non-workplace release of a highly hazardous substance or an environmentally difficult material If yes did the toller receive a life cycle evaluation (for example, disposal of products, handling returns and rejects) Does the Toller understand the information Was written acknowledgment obtained indicating that the information was received ... 

In the past, qualitative approaches for hazard evaluation and risk analysis have been able to satisfy the majority of decision makers needs. In the future, there will be an increasing motivation to use QRA. For the special situations that appear to demand quantitative support for safety-related decisions, QRA can be effective in increasing the manager s understanding of the level of risk associated with a company activity. Whenever possible, decision makers should design QRA studies to produce relative results that support their information requirements. QRA studies used in this way are not subject to nearly as many of the numbers problems and limitations to which absolute risk studies are subject, and the results are less likely to be misused. 

To better understand the limitations of ordinary clothing or work uniforms in jjrotecting you from hazardous materials we will look at the limitations of clothing designed for chemical protection. 

This valuable reference volume conveys a basic understanding of chemical reactor design methodologies that incorporate both scale-up and hazard analysis. It shows readers how to select the best reactor for any particular chemical reaction, how to estimate its size, and how to obtain the best operating conditions. 

What do we mean when we speak of an inherently safer chemical process Inherent has been defined as existing in something as a permanent and inseparable element, quality, or attribute (American College Dictionary, 1967). A chemical manufacturing process is inherently safer if it reduces or eliminates the hazards associated with materials and operations used in the process, and this reduction or elimination is permanent and inseparable. To appreciate this definition fully, it is essential to understand the precise meaning of the word hazard. A hazard is defined as a physical or chemical characteristic that has the potential for causing harm to people, the environment, or property (adapted from CCPS, 1992). The key to this definition is that the hazard is intrinsic to the material, or to its conditions of storage or use. Some specific examples of hazards include ... 

Deciding among a number of process options having inherent safety advantages and disadvantages with respect to different hazards can be quite difficult. The first step is to understand thoroughly all hazards associated with the process options. Process hazard analysis and evaluation techniques are appropriate tools (CCPS, 1992). These include ... 

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