"My Regulator Won't Work"


Larry "Harris" Taylor, Ph.D. 

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It was a hot, humid Michigan summer day. An overweight student diver was struggling to get into his wet suit. His skin was flushed and he was sweating profusely. When he finally got into his wet suit, he tried his regulator and then stated, "My regulator won't work."

I checked that the air was turned on and his spg indicated 2900 psig. I tried his regulator and it appeared to work, delivering abundant air on inhalation.

I suggested that the student move to the shade and rest. When the sweating reduced and his skin color returned to normal, I asked him to try his regulator and he was delighted to find that it worked. We then did our training dives without incident.

I have seen this scenario several times in my teaching career.

I strongly suspect the culprit is carbon dioxide. The build-up of CO2 creates a number of physiological responses: profuse sweating, flushed skin, more rapid breathing and heart rate, and ultimately a sharp pain in the center of the forehead. There is a profound sense of being air starved. This situation can be interpreted by the primitive brain as the breathing device (regulator) is not functioning.

I have seen a diver spit out their regulator at depth (~ 100 ffw) and bolt for the surface (fortunately, I was close enough to grab them and slow their ascent). On reaching the surface, the bolting diver stated that their regulator had stopped working at depth. However, when tested on the surface, the regulator appeared to function normally with abundant air remaining in their cylinder. After a brief rest, we slowly returned to depth and continued the dive without incident.  

I strongly believe that some perceived out-of-air emergencies are repetitions of this "my regulator won't work" event.

The points are:

1. Before concluding that there is no air, check the spg.

2. Physical exertion builds up CO2.

3. Divers should pace themselves to minimize exertion. This is particularly important when dressing for a cold water temperature on a hot, humid day.

4. The excess carbon dioxide (CO2 ) can alter breathing and heart rate ... ultimately leading to a perception of regulator dysfunction.

5.. The perception of regulator dysfunction can lead to inappropriate conclusions and potential life-threat.

What to do:

Carbon dioxide build up is a vicious cycle: increased CO leads to more rapid (decreased efficiency) rate of breathing (this poor ventilation increases CO2 load) ... which exacerbates the CObuild-up ... repeat with ever increasing CO2 level.

When breathing rate increases, it's time to slow down. If conditions permit, close your eyes and imagine a Stop sign (It is red, with white letters spelling STOP). This act of imagining the sign slows breathing rate and facilitates removal of excess CO2 . Rest until the air-starved perception disappears.


After a surface swim to a descent point, rest on the surface to allow breathing rate to return to normal. If surface conditions are uncomfortable, descend to ~ 10 feet and rest a bit before continuing descent.

Finally, maintain good physical conditioning to increase aerobic efficiency.


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 About The Author:  

Larry "Harris" Taylor, Ph.D. is a biochemist and Diving Safety Coordinator at the University of Michigan. He has authored more than 100 scuba related articles. His personal dive library (See Alert Diver, Mar/Apr, 1997, p. 54) is considered one of the best recreational sources of information In North America.

  Copyright 2001-2022 by Larry "Harris" Taylor

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