Hazards search

Some examples of those methods, commonly used for hazard search in chemical processes, are presented in Section 1.5. 

Chapters bear titles such as, Preparing for Hazards Evaluation Studies, Hazards Identification Methods and Results, and Selecting Hazard Evaluation Techniques. Supplemental Questions for Hazards Evaluation in Appendix B is excellent. Appendix B contains some of the important questions that are not thought of when performing a HAZOP study. There are 45 pages of probing questions on the process, specific classes of equipment, operation and maintenance, and hazard searching review. List price 120. 

Online information on hazardous substances. Includes response information and medical effects data with unique search capabilities. Cost is 120 per hour (1983). 

Hazardous materials iransponation regulations on disk. System displays text of regulations by chemical name or number. Also searches by keyword. Updates to regulations are provided on a monthly basis. 

The wide array of choices available to research chemists necessitates a diligent search for hazards to select the inherently safest chemistry. One of the means to search for hazards is to conduct a literature search, looking in particular for reports of incidents occurring in processes using the same or similar process chemistry being considered. 

Table 4.1 is a representative list of the types of hazards and hazardous events that research chemists are attempting to address in searching for the best chemistry. Some key factors to consider relative to process hazards include ... 

The identification of hazards includes both a search for those hazards reduced or eliminated by inherently safer design, and a search for hazards controlled by instmmentation and administrative procedures. 

Research chemists cannot do these searches independently. There are a number of tools designed to identify and evaluate hazards. Several of these "identification tools are described below. 

Certain molecular groupings are likely to introduce hazards into a process. The research chemist should identify groupings and molecular structures that may introduce these hazards. A search of the open literature will assist in identifying which types of compounds are likely to create potential hazards. Table 4.2 presents molecular structures and compound groupings associated with known hazards. The groupings in the table were developed from CCPS (1995d, Table 2.5), and Medard (1989). The table is not all-inclusive. 

The RMC HARIS (Hazards and Reliability Information System) programs provide organizations with a data ban)c of reliability, maintainability, accident, and source-abstract data. The programs permit the input of information in a standard data sheet format. Search capability is built into the programs for retrieval of these data sheets against specific search profiles. HARIS presently contains over 4400 data sheets. 

The alternative is hexane, which because of the explosion hazard requires a more expensive type of extractor construction. After the extraction the product is dull gray. The continuos sheet is slit to the final width according to customer requirements, searched by fully automatic detectors for any pinholes, wound into rolls of about 1 m diameter (corresponding to a length of 900-1000 m), and packed for shipping. Such a continuous production process is excellently suited for supervision by modern quality assurance systems, such as statistical process control (SPC). Figures 7-9 give a schematic picture of the production process for microporous polyethylene separators. 

In addition to the extra hardware required for these experimental runs, the ARC was operated differently than under standard hazard evaluation conditions. Instead of heating, searching and waiting, the samples were heated to a specified temperature and were then maintained isothermally at that temperature for extended periods of time. Pressure and temperature data were then monitored and stored in the microcomputer at a rate of 1 Hz. It should be noted that the apparatus reverts back to normal operation (i.e., tracking an exotherm), if a heat rise rate greater than 0.02 °C/min is detected. 

The reaction was reported by Henry J. Fenton [140]. This reaction is appHed in the treatment of hazardous organic wastes. A search for Fenton reaction in the website ISI Web of Knowledge [141] throws up thousands of scientific papers due to the exponential growth in its use over the years. It has been reviewed in various papers [142-145]. Below, the reaction pathway in the absence of an organic compound is given ... 

The current version of eChemPortal offers the possibility to retrieve information by searching on chemical names or CAS Registry numbers. The second phase will incorporate additional search options to retrieve and compile specific hazard or other effects data (e.g., toxicity endpoints) from the participating databases. 

A 100 Degree Rule was often used in the past throughout the chemical industry to assess whether an accident would occur. According to this rule, if the operating temperature of a process is 100 "C away from the nearest detectable exotherm observed in DSC (Differential Scanning Calorimetry) experiment the operation will not experience this thermal event. In such a case no more detailed information on hazards need be searched for. The 100°C degree rule is, however, often far from the safety margin The use of this rule was the reason of many accidents. 

A process is inherently safe in a rigorous sense, when no fluctuation or disturbance can cause an accident. To search for synthetic routes that avoid hazardous reactants, intermediates, and reaction mixtures, is an impetus to be seriously considered by chemists and process designers. Nevertheless, there will always be a need to cope with potentially hazardous materials and reaction mixtures in future process design work, the more so because process streams are expected to become potentially more dangerous in the future. The process streams will be more concentrated to increase energy efficiency, to ease purification, and to decrease the load of wastewater and spent acids. More concentrated process streams have a higher specific content of latent energy and are hence less stable. 

This iilustrative exercise completes the presentation of the different parameters that can be taken into account in the search for the fire hazard risk ievel of a substance. The methods available will now be discussed followed by a case study. 

Many substances must have Material Safety Data Sheets (MSDS) to describe their hazards and methods to correctly handle the substance. Using an internet search engine, find the primary health risk associated with argon, a noble gas. 

Transformation Rates. A literature search was conducted to determine rates of oxidation, hydrolysis, photolysis, and biodegradation. When no values were found, we made estimates based on our experience, known rates for similar compounds, and structure-activity relationships. In cases where there was great uncertainty, a transformation rate of zero was assumed so that the compound would be considered persistent. This would force a more detailed fate assessment to be conducted if considerations of toxicity indicated that the compound might be hazardous. 

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