When too much air is a bad thing

REPORTED INCIDENT

My buddy and I were participating in our first shore dive of the day on air, using my personal gear. My buoyancy compensator device (BCD) is about 20 years old, but the low pressure inflator hose was replaced about five years prior. I have been a certified diver for many years, having logged over 100 dives. With a divemaster, we descended to a depth of approximately 72 fsw (22 msw). About 25 minutes into the dive, I noticed I was having a lot of difficulty with my buoyancy. My BCD felt as if it was inflated with air, but I was unable to expel any using either my dump valves or low pressure inflator. I went to the divemaster and tried to signal for additional weights, but I was unable to control my buoyancy and stay at depth. I signaled to my dive buddies that I was going up, and I bolted to the surface. My computer was alerting me to slow down my ascent rate but I was unable to. At the surface I saw the problem. The auto-inflator button on my low pressure inflator hose was jammed. I was able to finagle with my inflator hose and dump valves, and finally I was able to expel the air in my BCD. I decided to descend again to meet back up with my buddies and found them at about 50 fsw (15 msw).

Approximately five minutes at depth, I again began struggling with being too positively buoyant and could feel air in my BCD but could not dump it. My tank pressure had also decreased to about 500 pounds per square inch (psi) within a short period of time. I signaled to my dive buddy to make the ascent with me and with her help, I was able to complete a safety stop. Once out of the water, I discussed this problem with my divemaster who suggested that I disconnect my inflator hose from my BCD for the next dive. I had a one hour surface interval, and then took his recommendation and made a dive to a maximum depth of 50 fsw (15 msw) for 60 minutes in which I encountered no issues. After the trip was over, I brought my equipment for professional inspection and maintenance at my local dive shop. It was found that the parts of my low pressure inflator hose were corroded.

COMMENTS

An auto-inflator button that is jammed open can present a real danger to a diver as represented by this case. Detaching the inflator hose's quick disconnect followed by releasing the excess gas in the BCD bladder using the dump valves is the best means to manage this problem when at depth. Depending on the training agency and instructor, the degree that this skill is taught and emphasized may vary. It can be challenging for a diver to recall it in an event such as this when quick thinking and rapid response is required. Practicing skills and taking time to rehearse management strategies for a variety of potential dive accident scenarios can aid preparedness.

In the event of a rapid ascent, there are a few things that can be done to try to mitigate it. The diver can orient him or herself horizontally and extend out his or her limbs in order to create drag and slow the ascent. If boat diving and an anchor line is available, grabbing on to the stationary rope and making a controlled ascent is optimal. In addition, being conscious to breathe normally and not holding breath may help to prevent pulmonary barotrauma (lung overexpansion).

Even though the diver in this scenario was able to empty the air in his BCD at the surface after the rapid ascent, descending again to meet with his buddies with the malfunctioning gear prior to addressing the issue was not optimal. Disconnecting the auto-inflate is the best practice, and after this occurs, the diver should then carefully consider if continuing to dive is ideal. Assessing the reason for the equipment failure and comfort with manual inflation of the BCD is important. If a rapid ascent or missed decompression obligation occurred, the potential for an increased risk of decompression illness (DCI) should also be taken into consideration when deciding whether or not to make a succeeding dive.

Perhaps the best means to diminish the potential for a dive accident to occur as a result of a stuck auto-inflate valve is to try to prevent it. Maintaining good buoyancy and being mindful of position while diving can help to reduce the risk of having the valves on the low pressure inflator hose come in contact with sand, silt, or other particulates that could become trapped. Thoroughly washing gear after each dive is important, as is visually inspecting all gear prior to each dive. Lastly, complying with the professional maintenance recommendations of the manufacturer is very important.

-Stefanie D. Martina