Fires, accidental types

Flame Types and Their Characteristics. There are two main types of flames diffusion and premixed. In diffusion flames, the fuel and oxidant are separately introduced and the rate of the overall process is determined by the mixing rate. Examples of diffusion flames include the flames associated with candles, matches, gaseous fuel jets, oil sprays, and large fires, whether accidental or otherwise. In premixed flames, fuel and oxidant are mixed thoroughly prior to combustion. A fundamental understanding of both flame types and their stmcture involves the determination of the dimensions of the various zones in the flame and the temperature, velocity, and species concentrations throughout the system. 

Tlie remainder of tliis cliapter provides information on relative physical properties of materials (flash points, upper and lower explosive limits, tlireshold limit values, etc.) and metliods to calculate tlie conditions tliat approach or are conducive to liazardous levels. Fire liazards in industrial plants are covered in Sections 7.2 and 7.3, and Sections 7.4 and 7.5 focus on accidental explosions. Sections 7.6 and 7.7 address toxic emissions and liazardous spills respectively. tliese latter types of accident frequently result in fires and explosions tliey can cause deatlis, serious injuries and financial losses. 

Moist potassium peroxodisulphate was accidentally exposed to traces of potassium hydroxide. It combusted spontaneously, causing the installations to catch fire. It is impossible to put out a fire involving this peroxydic compound with carbon dioxide or extinguishing powders although these agents are suitable for fires of chemical substances. Only water, which is usually not recommended in this case, can put out this type of fire. 

The extraction of the common metals from their ores in antiquity was based mainly on relatively simple equipment and processes. Lumps of copper or iron ore, for example, that may have formed part of a ring of stones around an ancient domestic fire and become embedded in its embers, could have been reduced to metal. It is quite reasonable to conjecture, therefore, that some prehistoric campfire became, quite accidentally, the first metallurgical furnace. All that is needed to convert a campfire into a smelting furnace is a small depression in the ground to receive the molten metal. A furnace of this type is illustrated in Figure 42 (Gowland 1912 Killick 2001). 

It is possible, therefore, that early humans may have accidentally made this type of dish when making fire to warm themselves or for cooking. Could such accidentally fired objects have given prehistoric humans the idea of modeling clay by hand and then firing it into pottery Any such hypothesis... 

Since accidental fire spread mostly occurs under natural convection conditions within buildings and enclosures, some examples of configurations leading to opposed or wind-aided types of spread are illustrated in Figure 8.3. Flame spread calculations are difficult... 

Accidental incidents involving new types of emergencies began to surface in the 1940s. They were linked with the behavior of certain chemical products collectively called hazardous chemicals (or hazardous materials) whenever they are misused or involved in unintended mishaps and fires. 

Fuzes utilizing centrifugal force must be fashioned so that they will not become "unarmed as the rotational velocity decreases. Some types, also are provided with devices (such as safety wire or cotter pin) to prevent accidental arming during handling or shipping preparations. Such "safety devices must be removed before firing... 

The State Police report quoted a refrigeration serviceman who reported that all of the valves on the evaporator were shutoff and the fire chief found a steam hose steaming underneath the machine. The serviceman had previously seen steam used to melt ice buildup around the valves and to heat the oil in the machine to make it easier to drain the oil. [ 51 The District Engineering Inspector s report confirmed that the machine was completely isolated and the ammonia system was not protected by a safety valve or any type of pressure-relief device. The cause of the accident was the presence of the steam ho.se underneath the equipment to melt the ice on the drain valve or to help evacuate the system. The inspector s report could not determine if these preparations were intentional or accidental. 151... 

Composite propellants. A composite propellant represents a group of propellants in which the composites, the fuels, and the oxidizers are separated materials. This type of propellant has replaced the sensitive propellants that suffer from the possibility of accidental initiation from fire, impact, electric spark, and others [4-6],... 

An emergency response to an incident that involves the accidental or intentional release of toxic chemicals or materials will typically be categorized as a HAZMAT incident. With the greater emphasis placed on this type of response, HAZMAT incident response plans have become increasingly standardized across the country. Specialized HAZMAT teams are routinely activated to respond in such situations. HAZMAT teams are typically part of the fire services and will possess chemical detection equipment. The first-responders, typically the police or fire department, must be capable of determining that a HAZMAT incident has occurred. Unfortunately, most emergency response vehicles do not have any chemical detection equipment, and the first-responder must make a quick judgment call whether or not to call in HAZMAT units. 

Accidental firing of the more sensitive types by stray currents, radio frequency (RF), or body static. ... 

The emergency plan covers different types of accidental situations such as criticality, fire, contamination, stack discharge, and accident from external cause, and is set up according to national (federal) guidelines. 

There are many types of accidents and spills involving hazardous materials. In 1992, the Ministry of the Environment listed 710 sueh accidents, which resulted, separately or simultaneously, in fires and explosions (47%), water pollution (30%), atmospheric pollution (20%), ground pollution (19%) (BARPI, 1992). Fifty-seven percent of these accidents were from industrial establishments. The transport of hazardous materials is often involved (16% of cases). Accidental pollution of unknown origin, which essentially damages natural environments, is caused by a significant number of the cases listed (15%). Agriculture is the source of 6% of these accidents, and 5% are from various trades and activities. 

Sulphur dioxide gas is produced in the process from the combustion of sulphur under controlled conditions. Exposure to sulphur dioxide gas may occur due to leaks in the process or if the sulphur store accidentally catches fire. Leaks can be detected by placing the stopper of a bottle containing ammonium hydroxide close to the area of the suspected leak. Dense white fumes are released by the reaction of sulphur dioxide with ammonia. Continuous cycle sequential monitoring systems e.g. Gelman type are recommended for the early detection of sulphur dioxide leaks, particularly if the plant is located inside a building. 

The full title of this standard is, Fire Prevention and Control on Open Type Offshore Production Platforms. It provides recommendations for rninimizing the likelihood of having an accidental fire, and for designing, inspecting, and maintaining fire control systems. It emphasizes the need to train personnel in firefighting, to conduct routine drills, and to establish methods and procedures for safe evacuation. The fire control systems discussed in this recommended practice are intended to provide an early response to incipient fires to prevent their growth. They provide a baseline, and are not intended to preclude the appUcation of more... 

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