This is a "heads up" for divers who may have an older inventory of gear. I was checking the pressure in some single cylinders that contained 32% nitrox. I was using a pressure gauge I have owned for many years like the dive shops use to check cylinders. I had forgotten that the old style gauge was oil-filled for vibration dampening purposes. I attached the yoke to a cylinder and opened the valve slowly as is my practice, then BOOM! I was thrown back against a cinder block wall by the concussion that hit me in the face and chest. The open valve was rapidly draining the nitrox. I could barely hear anything and was dizzy but managed to get up and grab the cylinder and throw it out onto the grass. I turned on a fan to get the smoke and odor out of my workshop and just sat down on the floor for a while. Later, after examining the yoke of the pressure gauge which was broken and blown off the tank, I saw that there was a small leak in the gauge that had allowed a small amount of oil to get into the pressure chamber. It was just enough to cause an explosion when combined with nitrox. Fortunately, the tank did not explode but I trashed it and the valve after the accident. IF YOU OWN AN OLDER SHOP BENCH PRESSURE GAUGE, CHECK IT OUT TO SEE IF IT HAS DAMPENING OIL IN IT.