Selecting the right explosion proof motor for a location where flammable gases and vapors are a continuous threat is a task of critical importance. It is completely necessary in these areas that the motor remains safe against ignition. A comprehension of this importance increases the difficulty of determining the best motor.
In order to be a suitable choice, the motor has to be approved for its designated Class locations. Given it has been in operation in a threatening location, sometimes workers just presume the motor is explosion proof. Nevertheless, just because the motor has been employed around explosive gasses or ignitable dust, it doesn’t mean that the motor is qualified as a Class I. For more information about hazardous regions, consult Chapter 5 from the National Electrical Code.
The Class I motor works by containing the explosion in the casing and without rupturing. At the beginning you will have a buildup of pressure at the point of ignition. Following that, the heated gas will move through flame paths, which are long passageways. The gas is given time to cool while it progresses toward the motor casing escape routes. When the gases eventually escape the motor, the temperature should be less than the Minimum Ignition Temperature (MIT) of the remaining gases in the region surrounding the motor.
Class I settings are the types where flammable gases, liquids, or vapors are explosive. If those elements represent a danger of explosion, then it qualifies as a Class I substance. As an example, gasoline is both explosive in its vapor form and ignitable in its liquid form. The Class I explosion proof motor is essential in locations where the fumes and liquid forms of gas are a constant presence.
Class II substances conversely are specifically dust forms. Dusts that conduct electrical current might earn a Class II designation. Areas where dust accumulates in sufficient amounts that explosive mixtures occur can also be specified as Class II. Hazardous dust presents a threat of exploding even in grain silos as the grain amasses. Coal dust is a hazard in coal mines. Basically, when dispersed combustible particles are present in big enough quantities to become flammable, the situation qualifies as a Class II.
Check the Label
It is important to choose the motor that best fits the situation when choosing motors for dangerous locations. For use in grain elevators and coal mines, for example a Class I motor wouldn’t be appropriate due to the high level of risk where the debris could explode. Specifically designed to confine the effects of an internal motor explosion is the Class I motor. You would need to carefully consider the risks that are most present when determining which explosion proof motor would be more appropriate.
Search for Class I or Class II locations on the Underwriters’ Laboratories label in order to figure out whether the motors are ideal or not for your needs. In some cases motors are appropriate for both types of settings and will carry approval for both Classes.
It can be helpful to speak with a field service representative of the insurance underwriter should there be any questions or concerns. Talking to the manufacturer or retailer of the motors is likewise helpful. They have an understanding of the particulars involved with the divisions and various classes indicating where the motor is suitable for use. If you have any kind of confusion, the specialists can provide the much wanted clarifications and help you get the proper explosion proof motor. The bottom line is that the chosen motor should have the appropriate classification in order for it to present the highest level of safety.
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