Tank Valve Etiquette

by Jesse Iacono:

As with many outdated habits in the scuba industry, there are a couple surrounding tank valves that simply refuse to die.  This article serves to identify the two most heinous and commonly occurring of the valve violations.  Changing these habits now could save your reputation and even your life.  Take heed of the following advice to avoid becoming branded as a valve violator!

Blasting Caps

Our first valve violator is certainly one who commands the attention of everyone at the dive site.  This individual can be found using blasts of gas from their tank to clear excess water off of their dust cap.  Although the results of this violation don’t present much of a direct threat to safety, their effects on surrounding divers are often unconsidered.

This method of drying dust caps is no more effective than blowing on them and/or using a towel to accomplish the same task.  This method is, however, exponentially louder and completely unnecessary.  The sound created can be startling and harmful to the ears of anyone in close proximity as well as a major distraction to the nearby dive professionals, boat crew, and captain.  Remember, these are the individuals whose focus on their task has an impact on the safety of those around them.  As a dive professional, the sudden sound of gas exiting a tank is interpreted as a red flag that something is wrong and needs to be dealt with immediately.  By creating this false alarm, one can expect the focus of the surrounding dive professionals to immediately be drawn to them as a second-nature response.  Also, when using a yoke valve, as the gas from the tank is reflected off of the cap and directed back towards the valve face, it can easily dislodge the o-ring, rendering the tank useless until the o-ring is found and replaced or a new one is purchased.  The costs associated, although not very significant, can add up over time and are easily avoided.

This habit seems to rampantly spread between divers, sometimes even those who were trained to do the opposite.  Eliminating this one from your repertoire can spread awareness and contribute to the violation’s overall demise.

The Quarter Turner

Our second violator is one who finds discomfort in certainty.  This individual can be found opening their valve all the way and bringing it back a quarter turn.  Such adherence to an antiquated practice could prove to be dangerous and even fatal.

This violation stems from a time when valves could get stuck in the open position if turned all the way open and not backed off by a quarter turn.  One can move confidently forward knowing that this situation will not occur when using any of the valves manufactured within the past five decades.  For some reason, even though the problem has long been solved, the habit sticks and is still transmitted from some instructors to their students.

When it comes to tank valves, there are only two options – the valve is open or the valve is closed, nothing in between.  When a valve is 100% open, the individual can breathe from their regulator while looking at their SPG and see no movement from the needle that indicates the contained pressure.  When a valve is 100% closed, the individual can breathe from their regulator while looking at their SPG and see that it either reads zero or, if previously pressurized, the needle will move towards zero with each breath.  During one’s final check, performed immediately before entering the water, this offers no confusion as to whether one will have gas to breathe once in the water.

The danger in the quarter turn violation is due to misinterpretation and inability to distinguish a valve that is a quarter turn opened vs. a quarter turn closed.  A valve that is turned on 100% and then a quarter turn off and a valve that is turned off 100% and then a quarter turn on will provide the same results when breathing from one’s regulator and monitoring the SPG at the surface – it will seem as though the valve is sufficiently opened and ready for the impending dive.  If one were to enter the water with a valve only a quarter turn open, they would quickly encounter a situation involving a lack of sufficient breathing gas, the results of which would prove to be both undesirable and dangerous.

Although making sure one’s valve is open seems simple enough, a single task can easily be overlooked when combined with the many that are required in preparation for a dive.  Add to this the commotion and excitement typically present at a dive site or on a dive boat and it can be easy to make mistakes.  Sometimes it isn’t even oneself that is the violator, but a well-meaning individual attempting to lend a hand.  By adhering to the correct valve procedures and making sure to always perform a final check before entering the water, one can begin their dive without question.

In every area of diving, make sure to think smart and safe.  Trust the information that dive professionals are presenting, but don’t ever be afraid to ask questions about why certain processes are observed.  If something seems counterintuitive, sometimes it just may be…



Sharks are among the most interesting creatures on Earth.  For centuries, humans have shared stories built around what they considered The Lion of the Sea; the stories that got the most attention were usually the scariest and most fantastic.  Recent books and movies continue that tradition and, in doing so, they have established our perception of sharks based upon numerous myths.  Let’s take a look at a few of those myths and the facts related to them.

1. Myth: All sharks are dangerous, man-eaters.
Reality: Sharks can be dangerous and they have attacked humans but that happens so seldom that it becomes statistically insignificant.  A person is more likely to be struck by lightning or win the lottery than to be bitten by the shark.  Of course, statistics don’t comfort much if you find yourself in the presence of a large shark yet it should help to know that it is not personal – at least, as far as the shark is concerned.

Of the nearly 500 types of fish scientists consider to be sharks, only three are responsible for the majority of attacks on humans: the great white shark, bull sharks, and tiger sharks.  These and a few other species dine on larger fish and creatures.  Their nervous systems and instincts compel them toward wounded and weak fish, since those are easiest to catch.  If they become attracted to a human, it is usually curiosity or a case of mistaken identity soon remedied once the shark gets close enough.  When sharks have bitten people, it is usually a singular bite because the shark learned that it is not the food he sought.

The largest of the species, Whale Sharks, may grow as large as 45 feet but they are no threat to humans because they feed upon plankton.  Divers who encounter whale sharks find them sociable and gentle.  Other shark species vary in size of just a foot (dogfish) to dozens of feet (basking sharks).  Nurse sharks that inhabit reefs soon become accustomed to humans, often accompanying divers as they explore the neighborhood.  Sharks can range from surface waters to depths of over a mile, as their species has done since the earliest days of aquatic life.

2. Myth: Sharks only inhabit deep water.
Reality: Many believe sharks live only in deep water with other large fish.  The truth is sharks go where their food lives.  Deep water sharks, like the goblin shark, remain on the ocean floor where they eat other bottom-dwellers like rays and mollusks.  Many other types visit offshore reefs to feed on the colorful tropical fish and transitory pelagic fish visiting there for the same reason.  Some sharks can swim right into the surf, chasing baitfish among human bathers – much to the surprise of all involved!

3. Myth: Sharks are voracious eaters, feared by all other sea creatures.
Reality: In fact, one often sees sharks swimming among fish, even surrounded by schools of fish at times.  To fish, a shark is a part of their environment – a dangerous element, to be certain.  Sharks move through the fish community, casually scanning for opportunity.  If a fish displays vulnerability or carelessness, the shark may suddenly turn and snatch it, thus removing from the community one of its weaker members.  Usually, a shark only eats when it is hungry and rarely will approach anything larger than what it might gobble in one swallow.  Otherwise, sharks patrol their beat as comfortably as any neighborhood cop.

4. Myth: Sharks are attracted to the color yellow.
Reality: While sharks have been seen to respond to solid yellow items in their environment, researchers have determined that they are more likely stimulated by the contrast rather than the color itself.  Contrast appears more vividly to a shark, so any solid patterns at the end of the light spectrum opposite colors more typical to the water environment (ie blue and green), will attract their attention faster.

5. Myth: Sharks can smell blood more than a mile away.
Reality: Well, not quite.  Researchers have discovered that sharks can sense blood as minute as one part per million, which is equal to a teaspoon of blood hundreds of feet away.  Sharks have a highly effective “nose” (actually, a nare) and olfactory system that can direct the shark accurately to the source of the smell.  A more useful sense for a shark’s feeding instinct however, is its ability to detect wounded or sick fish through a sophisticated system of nerve endings.  This detection system alerts sharks to vibrations caused by thrashing or abhorrent fish behavior hundreds of yards distant.  Thus, constant warnings to swimmers to avoid unnecessary thrashing in the presence of sharks or their food.

6. Myth: Sharks only live in salt water.
Reality: Many shark species are capable of surviving in fresh water and some, like bull sharks in South Florida, swim up freshwater tributaries to breed.  Sharks can be found throughout the Intracoastal Waterway, which ranges from salty to brackish to fresh in parts, because food is often plentiful and easy to catch in the restricted space.

7. Myth: If a sharks stops moving, it will die.
Reality: Sharks get life-giving oxygen like any other fish, by water moving over and through their gills.  Most fish, including sharks, are able to maintain that water flow by moving their mouths while they sleep (yes, fish sleep!).  Some shark species prefer to keep moving because it is more their predatory nature but others, like nurse sharks, can lie motionless for hours under a reef ledge.

8. Myth: Sharks are incapable of communicating.
Reality: People are surprised to learn that a shark’s brain is larger than that of most fish their size, such as the case with most predators on land or sea.  Although sharks do not socialize and develop sophisticated communication techniques like dolphins and whales (both of which are mammals, by the way), they are capable of demonstrating their interest and intentions.  When agitated or annoyed, sharks may hunch their backs much the way a dog or a cat may do.  

Researchers are also learning that sharks seem to communicate with each other through primitive sounds and electrical pulses received by others through a highly-evolved nervous system.  These signals are thought to be related to feeding and mating behaviors.

9. Myth: Sharks are an unimportant species.

Reality: Sharks are essential to maintaining balance among the food chain.  If they did not perform effectively, many species among their prey would suffer from lack of control.  All marine ecosystems require efficient predators to manage resident populations and sharks perform that duty well, when they are present to do so.  Unfortunately, sharks are not invincible, particularly to their greatest threat, humans.  Although most of a shark is not considered desirable food, their fins are a delicacy in some parts of the world.  Lack of restrictions and enforcement allows for severe overfishing and slaughter to the extent that shark populations are decreasing rapidly.  If enough sharks are removed to endanger the species, the negative impact will be felt throughout the entire marine environment.

Sharks are among the most recognized of marine species because of their sleek, distinctive appearance and the many salacious stories involving the ominous approach of their sinister dorsal fin.  They are highly-efficient killing machines but they are designed with the specific purpose of maintaining a delicate balance in the sea.  Admire their beauty, respect their strength, and most of all support the important part they play in our oceans.