You need to look at Pelco or Bosch for enclosures. You won't find cameras from major manufactures that are rated for hazardous locations. I have seen some Chinese cameras that claim they are rated for hazardous locations but I wouldn’t want to install one of them and be responsible for a exposition or fire.
IPVMU Certified | 01/08/14 01:29pm
TecPro out of Alaska has been making Mobotix based Class 1 Div 1 units for a while. While this is not soleley a housing (it is designed for certain models specifically), it might be worth looking at. I have no personal experience with them other than having seen one at a show:
TecPro Explosion Proof Housings
IPVMU Certified | 01/08/14 02:03pm
OnCam makes a nice 360 C1/D2 camera. 360 degree ExD certified camera
VideoTec also makes some very nice enclosures and camera systems for C1/D2 environments: VideoTec Explosion proof enclosures
We usually put IP cameras in Pelco explosion proof enclosures because the Pelco enclosures are less expensive than most. Pelco EHX*E Housings