SPARK ARRESTORS

This particular design is intended for a DC drilling motor used in a hazardous area. Because of the potential of this device to eject incendive particles into the surrounding atmosphere, there is a need for a spark arrestor. Not all spark arrestors are of the same design or intended for the same application. A spark arrestor designed for an internal combustion engine might not be suitable for a ventilated enclosure. Because of the different, unique application, there are not published guidelines on the subject; therefore, each application should be evaluated and an appropriate design selected and tested.

Several key elements must be taken into account for this particular application before a design is selected. the primary source of incendive particles and the transportation medium. The primary source of incendive particles on the DC drilling motor would be from the commutation that takes place within. Although a direct short circuit of the field coils would be a source, this type of failure is generally catastrophic to the point of electrical discharge through the motor frame in which case no spark arrestor of any type would protect the surrounding atmosphere. the transportation medium would be the forced air used to cool the motor and is an operational requirement for the rating purposes. the major restriction on this design would be not to inhibit cooling air flow through the motor and yet still provide a tortures path to extinguish the incendive particles. Many certifying agencies have adopted the idea of multiple, directional changes of airflow as the framework of a tortures path with smooth transitions for minimal restrictions.