Explosion-proof

Personnel involved in the handling of methanol require eye and skin protection from the irritating properties of methanol in the event of a spill. Contact lenses should not be worn, since plastic lens materials may absorb and concentrate methanol against the eye. Additional respiratory protection is not required with adequate local explosion-proof ventilation. 

The purification of Hquid nitro alcohols by distillation should be avoided because violent decompositions and detonation have occurred when distillation was attempted. However, if the distillation of a nitro alcohol cannot be avoided, the utmost caution should be exercised. Reduced pressure should be utilised, ie, ca 0.1 kPa (<1 mm Hg). The temperature of the Hquid should not exceed 100°C hot water should be used as the heating bath. A suitable explosion-proof shield should be placed in front of the apparatus. At any rise in pressure, the distillation should be stopped immediately. The only commercially produced Hquid nitro alcohol, 2-nitro-1-butanol, is not distilled because of the danger of decomposition. Instead, it is isolated as a residue after the low boiling impurities have been removed by vacuum treatment at a relatively low temperature. 

Generally, it is more economical to prevent explosive atmospheres ia rooms than to try to provide explosion-proof electrical equipment. Personnel should never be allowed to work ia a ha2ardous atmosphere. Where such an atmosphere cannot be avoided through control of flammable Hquids, gases, and dusts, access to the area iavolved should be limited and the area segregated by hoods or special ventilation. Electrical equipment on open, outdoor stmctures more than 8 m above-ground usually is considered free from exposure to more than temporary, local explosive mixtures near leaks (86). 

Piping and pumps used for transfer of the butanols can be made of the same metal as tanks. Centrifugal pumps with explosion-proof electric motor drives are recommended (34). 

The explosion-proof enclosure is designed such that an explosion in the interior of the enclosure containing the electronic circuits will be contained. The enclosure will not allow sufficient flame to escape to the exterior to cause an ignition. Also, a surface temperature rating is given to the device. This rating must indicate a lower surface temperature than the ignition temperature of the gas in the hazardous area. 

Explosion-proof enclosures are characterized by strong metal enclosures with special close-fitting access covers and breathers that contain an ignition to the inside of the enclosure. Field wiring in the hazardous environment is enclosed in a metal conduit of the mineral-insulated-cable type. All conduit and cable connections or cable terminations are threaded and explosion-proof. Conduit seals are put into the conduit or cable system at locations defined by the National Electric Code (Article 501) to prevent gas and vapor leakage and to prevent flames from passing from one part of the conduit system to the other. 

The dust-ignition-proof protection concept excludes dust from entering the device enclosure and will not permit arcs, sparks, or heat generated by the device to cause ignition of external suspensions or accumulations of the dust. Enclosure requirements can be found in ANSI/UL 1203-1994, Explosion-Proof and Dust-Ignition-Proof Electrical Equipment for Use in Hazardous Locations. ... 

Base Bare-tuhe external surface 1 in. o.d. hy 12 B.W.G. hy 24 ft. 0 in. steel tube with 8 aluminum fins per inch V -in. high. Steel headers. 150 lh./sq. in. design pressure. V-helt drive and explosion-proof motor. Bare-tuhe surface 0.262 sq. ft./ft. Fin-tuhe surface/hare-tuhe surface ratio is 16.9. 

Purchase Price Typical purchase prices, including drive motors, of tubular and disk sedimenting centrifuges are given in Table 18-16. The price will vary upward with the use of more exotic materials of construc tion, the need for explosion-proof elec trical gear, the type of enclosure required for vapor containment, and the degree of portability, and this holds for all types of centrifuges. 

This is a location which is not permanently contaminated but is likely to be prone to fire hazards during processing, storage or handling of explosive gases, chemical vapour or volatile liquids, although under careful and controlled conditions. Eor such locations in addition to a flame- or explosion-proof enclosure, type Ex. d, an increased... 

Figure 7.15 Flame paths and gaps in a flame-proof or explosion-proof motor...

Special-purpose motors such as increased safety motors, flame-proof or explosion-proof motoi s must be checked for gaps, clearances and creepage distances of all the mating parts forming flame paths. The construction of these motors must follow lEC 60079 as noted in the list of standards. 

In work places, T-R units should be installed where there is no danger of explosion, since explosion-proof measures are very costly and units in such installations are difficult to service and maintain. It is more convenient to bear the... 

Fig. 10-4 Insulating Joint with explosion-proof spark gap (I/sohz = 1 1/50//s = 2.2 kV surge current =100 kA). 1, insulating flange 2, hexagonal nut 3, insulator ring 4, insulator sleeve 5, insulator disc 6, steel disc 7, blue asbestos gasket 8, explosion-proof spark gap.

Today loading piers are mostly cathodically protected with impressed current. At moorings for tankers, cathodic protection rectifiers are installed on extinguisher bridges as far as possible from the hazardous area. Otherwise, they must be of an explosion-proof type. 

Electric motors to be Drip proof Splash proof TEFC Explosion proof ... 

For in-house correlations, the cost of electric motors should be correlated vs. horsepower with voltage, speed, and type of construction as correction factors or parameters. Correction factors for explosion proof or open drip-proof housings could he developed if most of the data is for TEFC (totally enclosed fan cooled) motors. Similarly, correction factors could be developed for 1,200 rpm and 3,600i pm with l.SOOrpm as the base. 

Must be air purged, explosion proof, or intrinsically safe to be used in hazardous areas. 

Explosion-proof motors can withstand an internal explosion without igniting a flammable mixture outside the motor. These motors are totally... 

Stores and work areas should be designated No Smoking areas and access controlled. Depending upon scale, explosion-proof electrics and static elimination may be required. 

Stores should be specially designed, constructed of non-combustible material, and located away from other hazards (e.g. brick coal bunkers are suitable for small samples, but purpose-built constructions with explosion-proof lights etc. are required for larger quantities). They should be designated No Smoking areas and be well labelled. 

Use only explosion-proof electrical equipment and spark-proof tools. 

Portable instrument should be of explosion-proof design fixed point systems may rely on remote sensing heads... 

These alloys have corrosion resistance similar to that of copper, with mechanical properties equivalent to mild steel. Because silicon bronzes do not generate sparks under shocks, they can be used in the fabrication of explosion-proof equipment. Compared to tin bronzes, the tinless bronzes have a higher shrinkage (1.7-2.5% against 1.3-1.5% of tin bronzes) and less fluid-flow, which is an important consideration in designing. 

Explosion-proof control room and operator always,present in control room l.lE-3 1.0E5 1... 

Ignition sources in the cupboard and duct system should be avoided. Plastic fans, electrical sockets external to the cupboard, and explosion-proof light fittings reduce the likelihood of ignitions. 

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