Explosion and fire hazards

Where possible, fire and explosion hazards should be avoided by using materials of low flammability. In many cases this will not be possible, but the hazards can be reduced by careful design of plant and operating procedures. 

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. 

Stages (1) and (3) are usually the most hazardous, but hazards can occur throughout the manufacturing cycle. The subsequent purification and drying of the product and the equipment used (dryers, blenders, dust filters and so on) are not considered in this guide, but are dealt with in Reference 109. 

Examples of incidents which can occur during the operation of a reactor are  

External ignition sources include unprotected electrical equipment, for example a sparking stirrer motor, and discharges of static electricity. 

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Example 9.1 A process involves the use of benzene as a liquid under pressure. The temperature can be varied over a range. Compare the fire and explosion hazards of operating with a liquid process inventory of 1000 kmol at 100 and 150°C based on the theoretical combustion energy resulting from catastrophic failure of the equipment. The normal boiling point of benzene is 80°C, the latent heat of vaporization is 31,000 kJ kmol the specific heat capacity is 150 kJkmoh °C , and the heat of combustion is 3.2 x 10 kJkmok. ... 

Checklists. A checklist is simply a detailed Hst of safety considerations. The purpose of this Hst is to provide a reminder to safety issues such as chemical reactivity, fire and explosion hazards, toxicity, and so forth. This type of checklist is used to determine hazards, and differs from a procedure checklist which is used to ensure that the correct procedure is followed. 

Iron dust does present a moderate fire and explosion hazard when exposed to heat and flame. Although normally not very reactive, under certain circumstances iron can react with water to Hberate flammable hydrogen gas. 

Physical Properties of Monomers. 1-Butene [106-98-9] is a colorless, flammable, noncorrosive gas its physical properties are fisted in Table 1, and its thermodynamic properties are available (16). Because 1-butene has a very low flash point, it poses a strong fire and explosion hazard. 

Bromates represent a potential fire and explosion hazard if heated, subjected to shock, or acidified. They should not be allowed to contact reactive organic matter, including paper and wood. Industrial quantities are packed in fiber dmms with polyethylene liners or in metal dmms. Laboratory quantities are supphed in glass bottles. For shipment, a yellow oxidizer label is required under DOT regulations. 

A concentration of 35,000 ppm in air produces unconsciousness in 30—40 minutes. This concentration also constitutes a serious fire and explosion hazard, and should not be permitted to exist under any circumstance. Any person exposed to ethyl ether vapor of any appreciable concentration should be prompdy removed from the area. Recovery from exposure to sublethal concentrations is rapid and generally complete. Except in emergencies, and then only with appropriate protective equipment, no one should enter an area containing ether vapor until the concentration has been found safe by measurement with a combustible-gas indicator. 

Explosibility and Fire Control. As in the case of many other reactive chemicals, the fire and explosion hazards of ethylene oxide are system-dependent. Each system should be evaluated for its particular hazards including start-up, shut-down, and failure modes. Storage of more than a threshold quantity of 5000 lb (- 2300 kg) of the material makes ethylene oxide subject to the provisions of OSHA 29 CER 1910 for "Highly Hazardous Chemicals." Table 15 summarizes relevant fire and explosion data for ethylene oxide, which are at standard temperature and pressure (STP) conditions except where otherwise noted. 

Table 15. Fire and Explosion Hazard Evaluation Data...

Improper cloth or filter media disposal may result in fire and explosion hazard. 

Flammability and related Fire and explosion hazard ASTM methods... 

Flammable limits Fire and explosion hazard Handling and storage ... 

Flash point (R) Fire and explosion hazard Abel... 

Volatility Fire and explosion hazard see Distillation range and... 

Oil content Disposal Incineration Fire and explosion hazard Extraction with solvent... 

Volatile matter Fire and explosion hazard Heating... 

Organic Peroxides — (R-O-O-R) are very hazardous. Most of the compounds are so sensitive to friction, heat, and shock that they cannot be handled without dilution. As a result, organic peroxides present a serious fire and explosion hazard. Commonly encountered organic peroxides include benzoyl peroxide, peracetic acid, and methyl ethyl ketone peroxide. 

The next simplest ether is the ether with the simplest alkane as one of the hydrocarbon backbones and the next alkane, which is methyl ethyl ether. Its molecular formula is CH3OC2H5. It is a colorless gas with the characteristic ether odor. It has a flash point of 31 °F, and an ignition temperature of only 374°F. This property, of course, makes it an extreme fire and explosion hazard. 

Eurnace Fires and Explosions, Hazard Workshop Module No. 005, Institution of Chemical Engineers, Rugby, UK, undated. 

This study investigated risks to the public from serious accidents which could occur at the industrial facilities in this part of Essex, U.K. Results are expressed as risk to an individual and societal risk from both existing and proposed installations. Risk indices were also determined for modified versions of the facilities to quantify the risk reduction from recommendations in the report. Nine industrial plants were analyzed along with hazardous material transport by water, road, rail and pipeline. The potential toxic, fire and explosion hazards were assessed for flammable liquids, ammonia, LPG, LNG, and hydrogen fluoride (HE). The 24 appendices to the report cover various aspects of the risk analysis. These include causes and effects of unconfined... 

The temperature and pressure of a liquid system are important in determining the effects created that result in a fire and explosion hazard. Because this relates to the flash point and flammability limits, see Tables 7-21, 7-22 and Figures 7-48, and 7-49A, and 7-49B [34]. 

It is important that the fire and explosion hazards of an area be carefully examined, because the expense of consistent installation of all the motors, controls, switches, instruments, and wiring can be considerable. Tables 14-8A and 14-8B summarize the National Eire Code for hazardous locations. It is equally important to be consistent and not install explosion-proof motors with nonexplosion proof wiring, because a failure in the conduit can still cause considerable damage. 

Plant areas are classified with respect to the possibilities of fire and explosion hazards existing or developing in the area while electrical equipment is in operation. The locations are... 

Fire and Explosion Hazard. Dangerous, as K nitrate is both a fire and expln hazard. As a strong oxidizer it can give up its oxygen to other materials to produce a vigorous reaction which may result in detonation. Toxic fumes are emitted on decompn. It is sensitive to shock, can be very easily detonated, and when mixed with flammable materials becomes very sensitive (Refs 6 10)... 

Fire and Explosion Hazard. Na nitrate is a dangerous fire and expl hazard. It can ignite on friction. When heated above 1000° or when heated with reducing materials, particularly cyanides, it emits toxic fumes on decompn (Ref 3)... 

Sodium Tetraperoxo-Moiybdate (2 ), MoNa2Og Explosive decompn under vacuum H.M. Castrantes et al, "Fire and Explosion Hazards of Peroxy Compounds , ASTM... 

Peroxomonophosphoric Acid, h3o5p Ignition when an 80% soln contacts org material H.M. Castrantas et al, Fire and Explosion Hazards of Peroxy Com pounds , A3TM Special Publ No 394, Phila (1965), 5... 

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