November 2002

Much dive equipment is life-support equipment. Like any other life-support equipment, it requires proper care and routine service to do its job. Failing to follow the manufacturer recommendations for equipment care can have tragic results. Take the case of Dick.

The Diver

Dick was an advanced diver in his late 40s with well over 100 logged dives. Although he was moderately overweight, he considered himself to be in reasonably good physical condition and fit to dive. It had been over two years since Dick had been in the water or checked his scuba equipment when he signed on for a wreck dive.

Dick's dive buddy suggested that Dick should have his equipment checked out before the dive and also complete a pool tune-up. Dick assured him that the equipment had been serviced just before he had placed it in storage and since it had only been used once, it should be fine. Dick also felt that his diving experience precluded the need for any kind of refresher training.

The Dive

The dive day could not have been better. Water temps were in the low 80s, and the seas were flat. Dick and his buddy entered the water and discovered that the wreck was clearly visible 90 feet below. As soon as they descended, Dick's buddy noticed that Dick's first stage was losing several bubbles of air with each breath. Dick also seemed to be having some difficulty breathing from the regulator. However, Dick was leading the descent and was moving so fast that his buddy couldn't stop the descent to see if everything was OK.

The Accident

At about 60 feet, Dick's movements became erratic and he began trying to swim back toward the surface, but he either forgot or was unable to inflate his BC and he continued to sink. Shortly before the divers reached the bottom, Dick's first stage began to bubble violently. His buddy swam over to donate his octopus. Dick pushed his buddy away, and dropped his weight belt in a frantic attempt to reach the surface. During Dick's rapid ascent, his buddy lost sight of him. The buddy returned to the dive boat, reporting the difficulties that had occurred. Dick's body was recovered just a few feet from the wreck on the sand bottom. His tank was empty, his mask was missing, and it appeared he had drowned.

Analysis

The autopsy report indicated that Dick died from heart failure, probably induced by severe strenuous activity. An inspection of Dick's regulator revealed significant corrosion on the inlet filter and the internal piston assembly, indicating that salt water had entered the regulator prior to storage. The filter corrosion alone was enough to decrease gas flow by 75 percent. The O-ring seal around the primary piston in the first stage had suffered catastrophic failure as a result of some abrasion, probably also caused by the corrosion. It seems likely that as Dick dropped below 33 feet, the volume of air he required for normal breathing exceeded what the regulator in its state of disrepair could deliver. This created physiological stress that increased Dick's breathing rate. His rapid attempts to breathe from the regulator caused the damaged first-stage piston O-ring to fail, quickly depleting his air supply. The physiological stress became too much for Dick, and he suffered a heart attack.

Lessons for Life

• Piston regulators control the flow of air by the use of sharp metal edges pressing into synthetic seats under spring or air pressure tension. Even when not in use, degradation of the seats can occur. First- and second-stage seats should be serviced annually to prevent catastrophic failure.

• Internal O-rings are made of synthetic or rubber compounds that dry and crack with age, even if not used. These O-rings should be inspected, lubricated and replaced annually.

• The salt crystals from just a few drops of seawater can significantly decrease the flow capacity of a regulator's inlet filter. Have the filter inspected, serviced or replaced annually.

• Salt water can cause significant corrosive damage to internal regulator components, and lead to regulator failure. It is critical that divers take care when cleaning their equipment after each dive to keep the interior components dry by either rinsing the regulator while it is connected to a tank or while the dust cover is securely in place. Regulators should also be stored with the dust cover in place. Once again, annual maintenance will generally catch minor lapses before significant internal damage is done to the regulator.

• Most divers, even those with health problems, are fit enough to dive when everything on the dive goes right. But when emergencies occur, divers need to be considerably more fit in order to respond safely.