Explosions flammable atmospheres

Inadequate ventilation in ducts due to partial obstructions or closed dampers leading to creation of flammable atmosphere. Possibility of fire/explosion. 

Provide automatic sprinkler system/inerting gas Provide deflagration vents Provide deflagration suppression system Monitor flammable atmosphere/fire Provide nitrogen blocks (nitrogen injection to stop flame propagation) or other explosion isolation measures... 

Vacuum transfer into reactor, drum or feed tank runs dry, resulting in air being pulled into vessel, creating flammable atmosphere. Potential for fire/explosion. 

Ignition of flammable atmosphere for open filters or solvent may be above flash point with air present when cleaning or unplugging closed filters. This may necessitate tight control of ignition sources to prevent a fire/explosion. 

General measures for controlling flammable atmospheres inside equipment are described in NFPA 69 Explosion Prevention Systems. These measures do not necessarily prevent flammable atmospheres in some practical cases, such as when powders are added to an inerted vessel via an open manway. Where possible such cases are identified in the relevant sections of Chapters 5 and 6. 

Flammable atmosphere Any atmosphere that represents a fire or explosive hazard by virtue of gases, vapors, or dusts contained in it. 

FPN No. 1) As a guide in determining when flammable gases are present continuously, for long periods, or under normal conditions, refer to. Recommended Practice for Classification of Locations for Electrical Installations of Petroleum Facilities, API RP 500-1991, Electrical Apparatus for Explosive Gas Atmospheres, Classifications of Hazardous Areas, lEC 79-10 and. Institute of Petroleum Area Classification Code for Petroleum Installations, IP 15. 

EXPLOSION and FIRE CONCERNS powdered form is combustible NFPA rating Health 0, Flammability 2, Reactivity - violent or explosive reaction when heated with ammonium nitrate ignites or reacts violently with bromine pentafluoride incandescent reaction with nitrogen oxide or sulfur dioxide reaction with mineral acids may liberate hydrogen gas reacts readily with dilute acids to form chromous salts incompatible with oxidants potentially explosive in atmospheres of carbon dioxide use dry chemical, carbon dioxide, water spray, fog, or sand for firefighting purposes. 

Using explosion-proof electrical equipment in flammable atmospheres... 

There are several area classification standards such as API RP 500 (2012), API RP 505 (1997), NFPA (National Fire Protection Association) publication 70 (2013), NFPA publication 497, NFPA 70, and local standards in practice. They define classified areas surrounding the individual equipment, based on characteristics and probability of leaked/released liq-uid/gas/solids. This approach reduces fire/explosion risk due to the simultaneous occurrence of a flammable atmosphere and eleetrical ignition to an acceptable level. The project team can use an appropriate area classification standard acceptable to the company and local government authorities. 

A hazard analysis, for example a HAZOP study (vid. Sect. 9.1.2.3, serves to identify the necessary preventative or protective safety measures. Constructive measures of explosion protection are necessary if the occurrence of flammable atmospheres and sources of ignition cannot be totally avoided. 

In all cases, for a fire or explosion to occur a flammable atmosphere and a source of ignition must be present at the same time. A general principle is therefore to avoid one and preferably both of these conditions. 

To prevent an explosion from occurring it is necessary either to avoid the formation of a flammable atmosphere or to ensure all potential sources of ignition are eliminated. The basic approach to explosion prevention can be illustrated by referring back to the fire triangle, which shows the three components necessary for combustion. 

These regulations illustrate a trend that is occurring in safety legislation, which is now starting to move from a prescriptive approach with definitions of what has to be done in specific situations to a more risk-based approach where the precautions and actions taken are left to the individual user provided they meet certain risk-based criteria. A proposed European Directive concerning minimum requirements for improving the safety and health of workers potentially at risk from explosive atmospheres extends this concept to all work places where flammable atmospheres may be formed. When adopted, this will require all employers to carry out a hazard assessment to identify whether a flammable atmosphere is likely to exist and, where so, to demonstrate that appropriate technical, organisational and other measures appropriate to the nature of the operation have been taken to minimise the risk. 

Water reactive materials are those that react violently with water. Alkali metals (e.g., hthium, sodium, and potassium), many organometallic compounds, and some hydrides react with water to produce heat and flammable hydrogen gas, which can ignite or combine explosively with atmospheric oxygen. Some anhydrous metal halides (e.g., aluminum bromide), oxides (e.g., calcium oxide), and nonmetal oxides (e.g., sulfur trioxide) and halides (e.g., phosphorus pentachloride) react exothermically with water, and the reaction can be violent if there is insufficient coolant water to dissipate the heat produced. 

An atmosphere that, hy reason of being explosive, flammable, poisonous, corrosive, oxidizing, irritating, oxygen deficient, toxic, or otherwise harmful, may cause death, illness, or injury. 

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