Solvents fire hazard

The vapor-laden air feed to the system is usually filtered at the inlet of the recovery plant to prevent dust or other particulate matter from entering the activated carbon bed. The concentration of solvent vapors in the air entering most solvent recovery units ranges from about / to 2 Ib/cu ft. With flammable solvents, fire-hazard considerations limit the maximum allowable solvent concentration. This should be less than 50% of the lower explosive limit (LED when continuous monitoring is used, and less than 25% of the LEL when intermittent monitoring is employed (Parsons, 1988). Data on LEL for organic compounds are available from the Underwriters Laboratories, Inc. Values for common solvents in air are given in Chapter 13 (Table 13-4). 

FIRE HAZARDS ATTENDING THE DISTILLATION OF INFLAMMABLE SOLVENTS... 

Both functional and decorative coatings can be appHed to paper from latices. The aqueous dispersions can be used on conventional paper converting machinery which usually cannot handle hot melts and solvent coatings. The lack of fire hazard because of absence of solvents is an added advantage of the latex system. 

Organic compounds of bromine usually resemble their chlorine analogues but have higher densities and lower vapor pressures. The bromo compounds are more reactive toward alkaUes and metals brominated solvents should generally be kept from contact with active metals such as aluminum. On the other hand, they present less fire hazard one bromine atom per molecule reduces flammabiUty about as much as two chlorine atoms. 

The drying of flammable solvents with sodium or potassium metal and metal hydrides poses serious potential fire hazards and adequate precautions should be stressed. 

Vinyl resins Air drying Solvent evaporation Blends usually rich in ketones Very good Very good Very good Poor Good Fire hazard Flash point usually below 23°C... 

Cellulose nitrate Air drying Solvent evaporation Blends of esters, alcohols and aromatic hydrocarbons Fairly good Bad Good Poor Very good Fire hazard Statutory regulations governing use... 

It must be borne in mind that in spite of the fact that the solvents have normal boiling points below 90-96°, they cannot always be completely removed by heating on a steam or water bath when they form part of mixtures with less-volatile liquids. Simple distillation may lead to mixtures with higher boiling points than the individual solvents, so that separation of the latter may not be quite complete. In such cases the distillation should be completed with the aid of an air bath (Fig. II, 5,3) or an oil bath the fire hazard is considerably reduced since most of the solvent will have been removed. 

Fire hazards attending the distillation of inflainmablc solvents... 

Under appropriate conditions, dichloroethylene, previously thought to be nonflammable, can cause a fire hazard [1], Addition of a hot liquid to the cold solvent caused sudden emission of sufficient v apour to cause a flame to flash back 12 m from a fire. Although the bulk of the solvent did not ignite, various items of paper and wood in the room were ignited by the transient flame [2],... 

Acylation of diethyl succinate by ethyl trifluoroacetate in presence of sodium hydride and in absence of a solvent is hazardous, fire or explosion occurring on 2 occasions some 10-20 min after adding a tittle of the succinate to the hydride-trifluoroacetate premixture at 60°C. Presence of a solvent appears to eliminate the hazard. 

Since potassium will burn in air, it is important to cut, slice, or powder the metal under an inert hydrocarbon solvent such as kerosene, toluene, or xylene. The air in the reaction flask should be displaced by an inert gas such as nitrogen. In this manner, fire hazard in handling potassium metal will be minimized. 

Reactions at atmospheric pressure may also be performed using MW ovens modified so that a reflux condenser can be attached outside the oven [7, 19]. Since volatile solvents are contained in MW reflux, the fire hazard is minimized. Mingos has re-... 

Acetone is used as a solvent in a laboratory. There is some concern about the fire hazards associated with the acetone. One solution is to dilute the pure acetone with water, thus providing an increased flash point. What mole fraction of water in a water-acetone mixture is required to increase the flash point of the mixture to 100°F Acetone is completely soluble in water. 

In studying the environmental effects of naphtha, it is necessary to relate volatility to the fire hazard associated with its use, storage, and transport, and also with the handling of the products arising from the process. This is normally based on the characterization of the solvent by flash point limits (ASTM D56, D93 IP 34, 170)... 

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