A month or two ago, I was assisting with an AOW class, where the o-rings on one of the student's yoke tanks burst underwater. I signaled the instructor that there was a problem with one of the students, who immediately got me to air share with her while he turned off her tank. I then ascended with her and escorted her back to the boat to get a fresh tank.
However, I now have some questions about turning off the tank. Would turning off the tank valve result in water ingress into the first stage, after the air in the first stage has escaped, due to the seal now being broken? I'm thinking that keeping the tank turned on and the regulator remaining pressurized would prevent the water from getting in at the cost of more air escaping from the tank during the ascent. If the regulator in question belonged to me I might have opted for keeping the tank on so that salt water doesn't get in, assuming my understanding of what will happen if the tank is turned off is correct.
FYI, this happened at the start of the dive, only about few mins in and we were relatively shallow, about 10m, so we had plenty of air to get back to the surface and to the boat.
However, I now have some questions about turning off the tank. Would turning off the tank valve result in water ingress into the first stage, after the air in the first stage has escaped, due to the seal now being broken? I'm thinking that keeping the tank turned on and the regulator remaining pressurized would prevent the water from getting in at the cost of more air escaping from the tank during the ascent. If the regulator in question belonged to me I might have opted for keeping the tank on so that salt water doesn't get in, assuming my understanding of what will happen if the tank is turned off is correct.
FYI, this happened at the start of the dive, only about few mins in and we were relatively shallow, about 10m, so we had plenty of air to get back to the surface and to the boat.