Cooling hazard

A much greater yield can be had if the chemist uses carbitol as a solvent instead of propanol [62]. Carbitol is a really hazardous solvent and should not be breathed or placed on one s skin. The reaction proceeds exactly as before except that after 24 hours of reflux and cooling the mixture is slowly poured into 1500mL ice cold dH20. The upper solvent layer is separated and the aqueous layer extracted with 200mL ether which is then combined with that upper solvent layer. The combined solvent portions are vacuum distilled to afford safrole-azide (or phenylisopropyi-azide for amphetamine) with the yield rising to 70%. 

When antifreeze becomes unsuitable for use, either because of depletion of inhibitors, presence of corrosion products or corrosive ions, or degradation of the fluid, recycling and reuse of the antifreeze, rather than disposal, may be considered. Although ethylene glycol is readily biodegraded in typical municipal waste treatment faciHties, antifreeze disposal becomes problematic because the coolant may contain hazardous quantities of heavy metals picked up from the cooling system. Recycling may be economically preferred over coolant disposal and reduces the concern for environmental impact. 

Liquid bromine produces a mild cooling sensation on first contact with the skin. This is followed by a sensation of heat. If bromine is not removed immediately by flooding with water, the skin becomes red and finally brown, resulting in a deep bum that heals slowly. Contact with concentrated vapor can also cause bums and bflsters. Eor very small areas of contact in the laboratory, a 10% solution of sodium thiosulfate in water can neutralize bromine and such a solution should be available when working with bromine. Bromine is especially hazardous to the tissues of the eyes where severely painfiil and destmctive bums may result from contact with either Hquid or concentrated vapor. Ingestion causes severe bums to the gastrointestinal tract (62,63). 

The carbonates should be plainly labeled and stored in cool, dry areas away from sources of ignition. The U.S. Department of Transportation (DOT) Hazardous Materials Regulations control the shipment of carbonates as described in Table 8. 

Fire or explosion hazards require special motor enclosures. Hazards include combustible gases and vapors such as gasoline dust such as coal, flour, or metals that can explode when suspended in air and fibers such as textile lint. The land of motor enclosure used depends on the type of hazard, the type and size of motor, and the probability of a hazardous condition occurring. Some available enclosures are explosionproof motors, which can withstand an internal explosion force-ventilated motors cooled with air from a safe location and totallv enclosed motors cooled bv air-to-water heat exchangers and pressurized with safe air, instrument air, or inert gas,... 

After the incident, an investigation team determined that the first operator had not added the initiator when required earlier in the process. When the relief operator added the initiator, the entire monomer mass was in the reactor and the reaction was too energetic for the cooling system to handle. Errors by both operators contributed to the runaway. Both operators were performing many tasks. The initiator should have been added much earlier in the process when much smaller quantities of monomer were present. There was also no procedure to require supervision review if residual monomers were detected. The lesson learned was that operators need thorough training and need to be made aware of significant hazardous scenarios that could develop. 

The rotor design, its cooling system or the motor size itself may have to be changed substantially for motors to be installed in fire hazard environments to limit their temperature rise in adverse operating conditions within safe limits (Table 7,6). 

Textile motors Crane motors Determining the size of motor Sugar centrifuge motors Motors for deep-well pumps Motors for agricultural application Surface-cooled motors Torque motors or actuator motors Vibration and noise level Service factors Motors for hazardous locations Specification of motors for Zone 0 locations Specification of motors for Zone I locations Motors for Zone 2 locations Motors for mines, collieries and quarries Intrinsically safe circuits, type Ex. f Testing and certifying authorities Additional requirements for ciritical installations Motors for thermal power station auxiliaries Selection of a special-purpose motor... 

Inert gas-filled motors can also be used in refineries and chemical plants, but their applications are limited. They have tightly fitted covers and oil seals around the shaft to minimize gas leakage, are continually pressurized with an inert gas or instrument air, and are equipped with an internal air-to-water heat exchanger. Inert gas-filled motors are suitable for any hazardous location but require auxiliaries such as cooling water, gas pressurizing system, and control accessories. 

In the forcc-ventilated or drip-proof types, the cooling air passes directly over the motor winding insulation. As a rule of thumb, a motor requires about 4,000 cfm of cooling air per thousand horsepower. Therefore, the possibilities of airborne dust and dirt collecting on the winding must he considered carefully. Filters in the air intake will lessen the hazards of this condition. Not much can be done about moisture drawn in with the cooling air, but careful selection of motor location inside ihe shelter can minimize the amount of wind-blown rain striking the motor. 

Generally the substances in this class are unstable when heated or exposed to light they should be stored cool and in the dark. However, for liquids with added stabilizer cooling may cause separation of the material from the stabilizer. Similarly, precipitation of a potentially explosive compound from a diluent may occur on cooling. In both cases this can represent a hazardous situation. 

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