Vent fire control system

Figure 19. Drawing of vent fire control system...

By identifying the potential sources of failures, it is possible to develop controls to address those hazards. These controls might be passive physical items (e.g., dikes, walls, vents), active physical systems (e.g., fire suppression, pressure limiters, temperature controls), or administrative procedures. 

Provide safety and alarm devices, such as fire-alarm systems, combustible-vapor detectors, flame arresters, pressure-relief venting of equipment, flame-failure controls for oil- and gas-fired equipment. 

Filtration of oxidizable materials can constitute a serious fire hazard. The ignition source can be a burning particle from the dryer or the static charge carried by the dust particle. Because of this, bag-house systems should be equipped with automatic devices for closing off the airflow in case of fire, should be provided with adequate sprinklers or chemical fire control apparatus, and vents should be provided on the side containing the dust particles. 

The preventive maintenance/predictive program covers pressure vessels and storage tanks, valve and piping systems, relief and vent systems, emergency shutdown systems, fire suppression systems, controls, and pumps. 

Various classifications of buildings may be required by a code to have smoke control systems. This includes particular requirements such as natural smoke venting, smoke exhaust systems, air handling systems of a particular design, and smoke doors. In particular, smoke must be excluded from fire-isolated exits. For natural venting, openings must be either openable or - if on a ground floor - shatterable. 

Activate fire, Start water systems. Control valves Ensure piping Vent and test... 

Quite clearly, this discussion will raise many points for the designers to consider. Similarly, each of the other hazard prompts can be addressed. They will undoubtedly raise questions about the design of the venting system (toxic and flammable emissions), how to deal with a failure of the cooling water supply to the condenser, how to control and monitor the effluent discharge even under conditions of plant malfunction, instrument failure, loss of other services such as electrical supply and steam, human error, ease of safe maintenance and so on. The prompt internal fire may lead to a debate on the start-up of the system, when acetone vapour and air will be present initially. 

Potential hydrocarbon losses from the overpressuring of operating vessels are controlled first by staged computer alerts and/or manual alarms to provide for correction of the condition. If the overpressure exceeds a second set point, pressure relief valves vent the vessel contents to a flare release system. The flare system provides a means of controlled burning of hydrocarbon vapors at a nonhazardous point to avoid fire or explosion risks. Smoke problems from flares are avoided by more efficient designs that use multiple nozzles and low pressure operation to promote clean combustion [57]. Greenhouse gas concerns should more frequently stimulate an interest in energy recovery options from flared hydrocarbons. 

Because there are no reasonable methods for mitigating risk following the occurrence of a BLEVE, all practical measures should be taken to prevent the causes of a BLEVE. This could include fixed water-spray systems over process vessels containing flammable liquids or which could be exposed to flammable-liquid fire, ensuring that relief devices do not direct vented flammable vapors onto the container, systems for diverting spilled flammable liquid to locations that would not expose process vessels, and pubhc-address systems to warn persons to evacuate locations where loss of process control could lead to a BLEVE [14]. 

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