Fire damage, evaluation

Fire damage to cable trays can be caused by exposure to flames and heat from spill or pool fires below, falling burning liquids from above, thermal radiation from an adjacent fire, or fire originating among the cables themselves. Cable trays and other grouped cable, wire, and nonmetallic tubing runs should be evaluated to determine the potential for fire exposure where warranted by their size and cost or safety-related importance of their service. 

The primary evaluation criteria used for evaluating sprinkler effectiveness was the number of sprinklers that operated, the extent of fire damage, heating potential for material within the commodity cartons, and the magnitude and duration of ceiling steel temperatures. 

The evaluation of fire damage is determined by visual examination with particular emphasis... 

According to the Council Directive 96/82/EC and subsequent laws, the analysis of domino effects due to explosions and fires is carried out using simplified methods based on damage thresholds. This estimation is based upon technical assessments, which are not probabilistic methods and do not take into account uncertainties (Milazzo Aven, 2012). Concerning domino effects triggered by fires, the evaluation of the influence of the flame extent and temperature has been amply explored... 

Metal deck assembhes are tested by UL for under-deck fire hazard by usiag their steiaer tunnel (ASTM E84). The assembly, exposed to an under-deck gas flame, must not allow rapid propagation of the fire down the length of the tuimel. FM uses a calorimeter fire-test chamber to evaluate the hazard of an under-deck fire. The deck is exposed to a gas flame and the rate of heat release is measured and correlated to the rate of flame propagation. A different FM test assesses the damage to roof iasulations exposed to radiant heat. 

In many cases, it is not readily apparent how the potential impacts from different hazards can be translated into some common scale or measure. For example, how do you compare long term environmental damage and health risks from use of CFG refrigerants to the immediate risk of fatality from the fire, explosion, and toxicity hazards associated with many alternative refrigerants This question does not have a right answer. It is not really a scientific question, but instead it is a question of values. Individuals, companies, and society must determine how to value different kinds of risks relative to each other, and base decisions on this evaluation. 

An estimate is then made of the area (radius) of exposure. This represents the area containing equipment that could be damaged following a fire or explosion in the unit being considered. It is evaluated from Figure 7 in the Guide and is a linear function of the Fire and Explosion Index. 

There was no significant damage to equipment in the fire tests, and it was demonstrated that a Jet Airmix mixer may safely handle the mixing of RP formulations on a routine basis. Since a high risk of fire is always associated with any method of transfer of RP, a pneumatic conveying system [dynamic air, two phase positive pressure transfer system was evaluated to load RP into the Jet Airmix mixer. Electrostatic charge measurements were minimal and indicated the system was satisfactory to load the blender. 

A heat flux of 25 kW/m has been published as a general rule-of-thumb for damage to process equipment (Barry, 2002). Clearly, this excludes electrical and electronic equipment, which may fail to operate at much lower heat fluxes and resulting temperatures. For example, data on the thermal impact of fire on electrical and electronic equipment have been summarized for U.S. Navy applications (Scheffey et al., 1990). The following limits were derived from a literature evaluation ... 

Each identified hazard will have a range of possible scenarios it may not be reasonable to evaluate every scenario. Therefore, representative fire scenarios should be chosen to cover a range of foreseeable scenarios. The scenarios to evaluate are those where the initial release and ignition characteristics are likely to cause the most extensive damage, loss of production, and the greatest risk to personnel. The fire scenarios selected should have a sufficient inventory that will burn long enough to cause failure of equipment and/or the structure. 

Only noncombustible materials should be used in the construction of control room buildings. While walls of masonry construction offer greater protection from external fire exposure, control buildings can be of pre-engineered construction if fire or explosion exposure is minimal. When the possibility of damaging explosion overpressure exists, the entire building design must be carefully evaluated. 

Dow s Fire and Explosion Risk Analysis Program provides a step-by-step, objective evaluation of the realistic fire, explosion, and reactivity potential of process equipment and its contents. The procedure allows calculation of the damage that would probably result from, and the areas which could be exposed to, fire or explosion generated in the process unit being evaluated. Management can then decide unit spacing needed to protect people from injury and to keep potential property and equipment damage to acceptable levels. 

The destruction of scarce, critical, or one-of-a-kind equipment in or near a process unit could create many days of downtime, even with minimal fire or explosion damage. This potential for high losses due to business interruption might qualify such equipment as a pertinent process unit for evaluation. 

The replacement value of the property within the area of exposure represents the maximum probable property damage resulting from a fire or explosion in the process unit being evaluated. 

Dow Fire and Explosion Index. The Dow Fire and Explosion Index (F EI), developed by The Dow Chemical Company, is an objective evaluation of the potential of a facility for a fire, an explosion, or a reactive chemical accident. Its purpose is to quantify damage from incidents, identify equipment that could contribute to an incident, and suggest ways to... 

---