According to the use of the site, flameproof motor is divided into three categories, namely, class I, class II and class III.

    (1) I used in coal mine, which YBK2 series applies to the coal mine (mining work face) of explosive gas mixture consisting mainly of methane or coal dust in the place of the equipment; YB2 series I type, suitable for coal mine (non mining work face).

    (2) class II for inflammable and explosive gas and dust factories and other similar occasions. II type flameproof motor and the explosive gas mixture maximum experimental safe gap of its use, divided into A, B, C three levels. Can be written as A, Ⅱ B, Ⅱ C.

    (3) class III for explosive dust and fibers.