The proof marks are Exd Ⅱ BT4 and Exd Ⅱ CT4. Explosion proof Single girder overhead bridge crane is applied to sites, where is not higher than the II B or II C-class, and the sites with explosive air mixture formed with inflammable gas (or steam) and air whose factory ignition temperature groups of not less than the T4 group. We designs and manufactures the material handling equipment for the harsh and hazardous application environments, such as chemical plants, gas power plants, paint shops, oil refineries, and waste water treatment plants, etc.