Escalator hazards

Spatial coverage (At-Risk Volume Approach)—based on the correlation between flammable gas accumulation and the resultant overpressure upon ignition. The detection spacing is determined by estimating the size of the cloud that can present a credible escalation hazard. 

The fire detection grading approach is a coarse hazard assessment, which documents the credible fire hazards and defines and establishes acceptable fire detection performance requirements. The fire detection performance requirements are defined by determining what size of fire presents a credible escalation hazard. The systematic application ofthe grading process then develops an engineered detection system whose performance can be verified. The general process utilized to develop the detection layout is as follows ... 

Where the need for fire detection is identified, the required performance of the fire detection system is already specified as part of the grading process. Fixed fire detection is typically installed to protect equipment that is high value, long lead time, or likely to be significant fire escalation hazards. The performance specification defines fire size and response time thresholds for alarm and action(s). Fire hazards are defined by radiant heat output (RHO). RHO gives a reasonable indication of the potential damage and the probability that the fire will escalate or cause loss. The RHO should not be used to determine fire thermal loading onto equipment and structures. Table 8-3 compares RHO and flame area for some typical hydrocarbon fires. 

Close proximity of hazardous processes may result in releases or other hazardous conditions in one process affecting the neighboring process areas, thereby resulting in escalation of the hazard. 

The objective of emergency planning is to reduce die probability of serious loss due to a particular liazardous accident. The probability of an occurrence of a hazardous accident is first evaluated. It is tlien it is assumed tliat, if the accident occurs, tlie worst consequences will follow (tlie so-called worst-case scenario). Procedures for liandling a particular accident are tlien dex eloped and practiced, both to minimize tlie exposure of persoiuiel and to prevent escalation of the original incident. 

Hot gases rise by thermal lift. Hence in the open air they will disperse. Within buildings this is a serious cause of fire escalation and toxic/asphyxiation hazards if smoke and hot gases are able to spread without restriction (or venting) to upper levels. A balanced flue can serve to effectively isolate a combustion process in a gas-fired appliance, but must be sound in construction and unrestricted to avoid leaks. 

The purpose of the Dow Fire and Explosion Hazard Index (Dow, 1987) is to 1) quantify the expected damage of potential fire and explosion incidents in realistic terms, 2) identify equipment that would be likely to contribute to the creation or escalation of an incident and 3) communicate the fire and explosion risk potential to management. The Dow Index is the product of the Unit Hazard Factor and the Material Factor (Table 1). 

Domino effect An incident which starts in one piece of equipment and affects other nearby items, such as vessels containing hazardous materials, by thermal blast or fragment impact. This can lead to escalation of consequences or frequency of occurrence. This is also known as a knock-on effect. 

In this Chapter further evidence is provided that precursors exist long before they escalate into an accident. It will be demonstrated that the existence of precursor information could have been used to foresee and even prevent recent accidents with hazardous substances. Moreover, a set of precursors retrieved from 17 recent accidents in the Dutch chemical process industry is used to validate the 7-stage protocol developed in the previous Chapter. In spite of the limited accident information it is shown that if a proper control action had been initiated, all of these 17 accidents could have been prevented. 

Spatial coverage is a gas detection layout methodology that utilizes a goal setting or at-risk volume approach (Bond, 1993). The objective is to detect gas accumulations that can cause catastrophic escalation through a pragmatic methodology. For flammable gas hazards, this can be based on detection of... 

The CERCLA s creation was a response to the growing concern over escalating dangers associated with inappropriately disposed hazardous waste. The most commonly cited incident being the Niagara Falls, New York s Love Canal, where then-president Jimmy Carter declared the former landfill a federal... 

---