Ignition tools

Hot Work. The objective of a hot work standard is to prevent fires, explosions, and other causes of injury which might result from workplace ignition sources such as welding (qv), cutting, grinding, and use of electrically powered tools. The OSHA standards have specific requirements (36,94) for fire prevention and protection and a permit system. 

Although acetylene is considered to be a material having a very low toxicity, a threshold limit value (TLV) of 2500 ppm has been estabUshed by NIOSH. In the presence of a small amount of water carbide may become incandescent and ignition of the evolved air—acetylene mixture may occur. Nonsparking tools should be used when working in the area of acetylene-generating equipment. 

Figure 3.2.1 shows flame kernels of the schlieren photograph taken by a high-speed camera. These photographs can be compared with the calculated temperature distribution in Figure 3.2.4. As can be seen, both of them bear a close resemblance. From this result, the authors firmly believe that the numerical simulation is a significant tool for grasping the mechanism of spark ignition. Of course, the experimental work should also be of importance to verify the results obtained by numerical simulations. In this work, the authors mainly introduce the results of numerical simulations that have been obtained xmtil then in their laboratory.

In Chapter 3.2, M. Kono and M. Tsue examine the mechanism of flame development from a flame kernel produced by an electric spark. They discuss results of numerical simulations performed in their laboratory in confrontation with experimental observations and confirm numerical simulation as a significant tool for elucidating the mechanism of spark ignition. 

Use of a steel chisel to open a drum of carbide caused an incendive spark which ignited traces of acetylene in the drum. The non-ferrous tools normally used for this purpose should be kept free from embedded ferrous particles [1], If calcium carbide is warm when filled into drums, absorption of the nitrogen from the trapped air may enrich the oxygen content up to 28%. In this case, less than 3% of acetylene (liberated by moisture) is enough to form an explosive mixture, which may be initiated on opening the sealed drum. Other precautions are detailed [2], Use of carbon dioxide to purge carbide drums, and of brass or bronze non-sparking tools to open them are advocated [3],... 

Materials for a batch of ammonium perchlorate castable propellant were charged into a mechanical mixer. A metal spatula was left in accidentally, and the contents ignited when the mixer was started, owing to local friction caused by the spatula. A tool-listing safety procedure was instituted [1]. The literature on the kinetics of thermal decomposition has been reviewed critically [2],... 

Use of a rusty iron tool on an aluminium compressor piston caused incendive sparks which ignited residual propene-air mixture in the cylinder. 

Furthermore, it has been shown that the time period until ignition occurs, in the Cone calorimeter, is proportional to the inverse of the flame spread rate [16]. The Cone calorimeter can also be used to provide the mass loss rate information required for the simplified classification into categories of toxic hazard [1] quick toxic hazard assessment. Thus, the NBS Cone calorimeter is a very useful tool to overcome some of the disadvantages associated with measuring a single property at a time. 

Crawley and Grant (1997) have developed a risk assessment tool for new offshore installations. They have examined typical leak frequencies of equipment items and the ignition probability of these leaks in four pressure bands. With this information it was possible to define leak size and frequency for any piece of equipment and the ignited leak frequency. In off-shore installations gas separation vessels were found to have ten times higher ignited event frequency than oil pumps. 

American Petroleum Institute (API), Publication 2214. Spark Ignition of Hand Tools. Third Edition, API, Washington, D.C., 1989. 

The risk of explosion or fire associated with the use of mobile telephones in a LPG vehicle is extremely low. First, LPG vehicle fuel systems are closed systems with safety features to prevent accidental release of LPG. The risk of fuel leakage is less than that of a petrol or diesel vehicle. Second, LPG will only bum when mixed with air in proportions within the flammable limits and when there is an ignition source. Working with higher-pressure fuel systems requires special tools and... 

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