I thought I would relay an incident I observed on a boat within the last couple years. I found it interesting.
DM got ready to set the hook in 100 ft of water, second dive of the day. Tested his reg and it free flowed and would not stop. So he removed the reg and dove with the one reg that seemed to be working well. That reg stopped at 60 fsw. He thought his tank might not be on all the way but quickly discovered it was and made an emergency CESA to the surface. Other than being very winded he seemed ok but was told not to dive anymore that day.
The reg was examined but seemed to be working. Second DM dove with the REG but carrying back up air. The reg again stopped completely at 60 ft on a full tank of air but it did not matter since he had plenty of redundant air with him.
Later they took apart the faulty reg and found that it would stick in the off position.
What I take from this.
1. It is very rare but Regs can fail in the off position
2. That is not a problem IF you have a second functioning reg.
3. In my experience, some instructors/DM are more casual about routine maintenance than regular rec divers. This I do not know for sure, but my impression from the comments was that this DM had not been super conscientous about servicing.
DM got ready to set the hook in 100 ft of water, second dive of the day. Tested his reg and it free flowed and would not stop. So he removed the reg and dove with the one reg that seemed to be working well. That reg stopped at 60 fsw. He thought his tank might not be on all the way but quickly discovered it was and made an emergency CESA to the surface. Other than being very winded he seemed ok but was told not to dive anymore that day.
The reg was examined but seemed to be working. Second DM dove with the REG but carrying back up air. The reg again stopped completely at 60 ft on a full tank of air but it did not matter since he had plenty of redundant air with him.
Later they took apart the faulty reg and found that it would stick in the off position.
What I take from this.
1. It is very rare but Regs can fail in the off position
2. That is not a problem IF you have a second functioning reg.
3. In my experience, some instructors/DM are more casual about routine maintenance than regular rec divers. This I do not know for sure, but my impression from the comments was that this DM had not been super conscientous about servicing.