Explosion-proof motors

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. 

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

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

In Division 1 areas, motors and generators must be either explosion-proof or approv ed for the classification by meeting specific requirements for a special ventilation system, inert gas-filled construction, or a special submerged unit. Although explosion-proof motors are expensive, they normally are available. Explosion-proof generators normally are not available. 

These devices are tested only for internal explosions and not for external explosions pressurizing the devices from the outside. As an example, a factory-sealed push-button start/stop station connected to an explosion-proof motor starter cannot suffice as a seal for the motor starter conduit entry. A separate seal must be installed at the point of conduit entry. 

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. 

The geographical location as well as atmospheric conditions (moisture, vapors, dust, etc.) in which the motor must operate should be stated, because the manufacturer has experience in a wide variety of conditions and can recommend the type of motor and materials of construction, such as for fan and insulation. The process engineer must specify the nature of the hazard—that is, whether an explosion-proof motor is required. If it is required, the group hazard must also be identified. 

Petro, D. and Basso, D., Match Explosion Proof Motors with Variable-Erequency Controllers, Chem. Eng. Prog., V. 91, No. 10,p. 84 (1995). 

Motors are suitable for use in general purpose areas and in Class I, Division 2, Group C and D areas for a wide range of pump fluid temperatures. For Class I, Division 1 Group C and D U.L listed, explosion proof motore are available. 

High-speed blender fitted with leak-proof glass jar and explosion-proof motor Balances... 

Laboratory mill (Wiley, Standard Model No. 2G, or equivalent), equipped with a shield and an explosion-proof motor (class 2). 

An explosion-proof motor-driven grinder or steel or glass balls can also be used to grind the sample (see Critical Parameters). 

Explosion-proof motors are required to meet the National Electrical Code Standards for use in hazardous conditions. These are used where gas, dust, or vapors may be in hazardous concentrations and a spark from the motor could cause a fire or explosion. 

Standard safety procedures include attention to such matters as intraline distances to minimize explosion propagation, cleanliness, nonsparking equipment and explosion-proof motors, and location in selected areas away from the heavily populated areas. The development of continuous processes for explosive manufacture that use extensive automatic controls and minimize in-line quantities has contributed significantly to decreasing the hazards of operations. 

Motor J hp, split-phase induction, 60-cycle, 110-volt, a-c, General Electric explosion-proof motor... 

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