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As with many outdated habits in the scuba industry, there are a couple surrounding tank valves that simply refuse to die.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…

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61 replies
  1. Dan Blum
    Dan Blum says:

    In your article under “blasting caps” you attribute the “blast” intention as to “clear excess water off of their dust cap”. I was trained to use the air to clear water off the yoke valve on the regulator first stage (not the dustcap). Is your attributing it to clearing the dust cap a mistake and you really mean to tell us not to clear excess water off the first stage yoke valve? Please clarify.

    • Jesse Iacono
      Jesse Iacono says:

      Hi Dan!
      I appreciate your inquiry and would be happy to clarify. In my article, I only addressed using blasts to clear off the dust cap. I am aware that some use the blast method on the first stage as well. I did not address first stages in the article because, typically, the dust cap is what is exposed to the water and has excess water remaining on it that must be removed after the dive. The orifice of the yoke valve ideally should come off of the tank dry as it has been attached and pressurized to the valve face. Water present on the orifice, if any, is likely due to it dripping down when disconnecting the first stage from the tank valve.

      Regardless of which you are blowing off, using your breath and/or a towel, shirt, etc is very effective. Using blasts of gas to do so can be overkill and has even been attributed to blowing excess salt water into the orifice of the first stage, adding corrosion to the internal metal filter. My main point is that using the blast method is no more effective than blowing/wiping dry, but causes much more of a ruckus. By altering one’s process just a bit, they can achieve the same effect while being courteous to those around them.
      I hope this adequately addresses your question. Feel free to contact us back if you have any additional questions or concerns:)

      • Charlie
        Charlie says:

        I often see divers crack their tank valve to blow off the yoke retainer containing the sintered filter. I can only guess this comes from a misunderstanding of the dust cap cleaning method.

        The first stage should have remained attached to the tank valve during the entire dive, so it will be dry. Blowing a bunch of air and water around this inlet can only blow water where there was none before.

        As a tech who has been repairing scuba equipment for over 30 years, one of the first things I check when a customer brings in a reg is the condition of that sintered filter. Green means a complete overhaul.

        As recommended in this article, drying the cap with a towel, T-shirt, or even a friendly lick will reduce the amount of salt water exposure to your first stage.


    • Jovial
      Jovial says:

      sounded me more like nagging. certain things in certain industries are inevitable. it is not really a bad habit. Doesn’t bother me one bit when someone does it around me. If it’s not life-threatening, why complain…?

  2. Jason hirsh
    Jason hirsh says:

    I am some what surprised by this post but again when one starts throwing around the term antiquated and “the correct procedure”. ..
    I have taught the quarter turn principle for 25 years. A quick pool of instructors here found all teaching the same thing The rationale behind it was referred to as the “dive master” turn. The last thing a dive master on a boat will do is check to see if yyou tank is open. By turning it. If pegged open the valve can jam to the tune of two tanks a week at the resort I am now working at. The quarter turn in no way impacts air delivery.. It is less then one thread on the seat. In reading the article I am almost left with the impression the the procedure discussed is purely visual. .breath and gauge. Eve.n when diving myself I do the physical hands on check. I believe this procedure is valid and never heard it associated with tank valve issues other them j valves and early k valves having issues if opened only half way on air delivery. I have never heard of a “tank stick” issue” but we do have 4 or 5 a month. We chalk that up to “overethusatic” checking ir rechecking.

    I also question the validity if the statement that a valve a Quarter turn open will deliver air at the same as full open. I have no research to prove this or disprove this Other then one thread open on the seat is a lot different from 8. As far as provided. The usual indication of this ( but not always) is a moving preserve gauge while breathing.. There is no hArd and fast rule on this and it will be influenced by the regulator characteristics

    I would love to see source or reference for the conclusions raised on the second part I and my coworkers remain of the onion that the best check of the status of the tank valve is a physical Hands on…the quarter turn diea not impact this but provides a safety margain on a pitching dive boat platform

    As far as blasting caps. How about its just excessive noise serves no purpose The safety concerns are a little far reached. At our resort we have grown use to it and general I would be surprised if most working professionals would do more then shake their heAds

    • Jonathan
      Jonathan says:

      in my experience, a valve only a 1/4 turn open DOES breathe and operate different than a valve all the way open or a 1/4 turn from fully open – with some of the tanks that I have, if the valve is only 1/4 of a turn open, the SPG will drop with every breathe and then jump back once the breath is stopped, which can be rather worrisome to see!
      I also feel that breathing is more difficult with the valve only 1/4 turn open.

      • James T
        James T says:

        I have personally experienced what happens with a valve only 1/4 turn open (like the article mentioned, it was someone “just trying to help” ). It is definitely NOT the same as having the valve all the way open. The predive saftey check went fine, and so did the dive until I got down to about 110 bar, when I started to feel that the end of inhalation was more difficult. Initially it was so subtle that I even though I might be imagining it. It became more and more apparent as I used more air, and the needle on my SPG began to go down a bit with each breath, and then back up during exhalation. Once the pressure was down to about 90 bar, the needle would go ALL the way down with each inhalation, and take several seconds to go back up before I could get another breath. I borrowed my buddy’s octopus while he opened the valve all the way, and we were able to continue the dive with out further incident. Luckily this happened on a fun dive, and not while I was teaching.

        Regardless, I still teach opening the valve all the way, then a quarter turn back. Overzealous new divers WILL damage the valves by opening them all the way (and then some) but more importantly for the sake of what another poster called the “divemaster check.” With the diver on the edge of the boat ready to do their back roll, I steady them with a hand on the tank valve and do a quick quarter-turn-and-back to verify their valve is open. Given my experience, however, I emphasize in my instruction the importance of opening the valve (or checking it) yourself and not simply relying on the “breathe and see if the needle moves” technique.

        • James T
          James T says:

          Oh, and if you hold your dust cap flat against the valve, it’s not loud at all. Problem is, everyone holds it a couple cm away from the valve. On a small boat with a few divers, it’s not so bad, but on liveaboards with 60+ divers, it’s just obnoxious. I imagine that before too long, all regs will have ACDs (auto-closure devices) and dust caps will be a thing of the past.

  3. James
    James says:

    This article is a joke. Clearly the person who wrote it has no idea what they are talking about. Any dive professional worth their weight will tell you that even new cylinder valves can jam and still see it on a regular basis. As far as blasting air, it is just annoying and serves no purpose.

    • Jesse Iacono
      Jesse Iacono says:

      Hi James,
      Thank you for taking the time to read and provide feedback to my article. I am glad we can at least agree on the blasting topic:) I would certainly like to believe that I have some sort of idea of what I am talking about and I did intend some of the article to be humorous, so I am glad that you can have a laugh at it!
      Although I would not agree that valves jam as frequently as you indicate, I do recognize that they can and do in fact jam a little bit every now and then. I would not, however, attribute this solely to opening all the way. If someone were to crank the valve past the point where it wants to naturally stop or if the valve were subject to certain wear and tear and corrosion, then sure! Saying that this is solely based on opening all the way would be a reach in my opinion. Also, it can usually be corrected with a bit of force; I have never seen or heard of any reasonably modern valve becoming completely stuck in the open position.
      The main point of my article though, was to show that there is more uncertainty surrounding the quarter turn practice than with a straight up on or off mentality. I simply aim to transmit my opinion of the method that minimizes risk.

      • Paul
        Paul says:

        But surely the point of teaching the quarter turn back was to discourage new divers from opening the valve fully and over tightening it in an open state?

      • jason Hirsh
        jason Hirsh says:

        Jesse Perhaps you shopuld modify your article…You state “The main point of my article though, was to show that there is more uncertainty surrounding the quarter turn practice than with a straight up on or off mentality.” You clearly state in your article Such adherence to an antiquated practice could prove to be dangerous and even fatal.” That simpkly is not the case I would love to see the facts supporting your statement. I have been maintain tanks for 25 years (not as long as Steve Prosterman) and the quatter turn is like not running you car or tools flat out. Tanks valve parts are re;atively fragile in terms of scuba gear. Also you state “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.” That is simply not true (check the other responses) or at least in 100% of the circumstance (there are no universal truths) Also your statement “a single task can easily be overlooked when combined with the many that are required i” in regards to checking the tank valve….Every organzations have pre side saferty checks that involve checking air.. granted that is lgeneraly limired to gauge but that is simply a mistake that should be corrected. Is all the way open like you like bad …. from safety no but from gear perspective it is very damaging. I know safet comes first but you were concerned ovet tyhe cost of an o-ring should you share the same concern for the tank valve?

  4. Steve Prosterman
    Steve Prosterman says:

    I have to comment on the concern of all the way open versus 1/4 turn back. I have been rebuilding valves for 33 years and have seen many stipped valves from being opened too hard. I do still see when those who turn them all the way and then are checked and turned harder, that they more frequently need rebuilding as they get striooed. There is no new materials inside the valve that prevent this as some have said. The stem inside does get rounded off from being square without much effort. To call it dangerous to use the 1/4 turn back is quite a stretch. When I have students and researcher who use the all the way open method, I end up having to rebuild valves more frequently. Talking to others I know that actually work on gear a lot, I find they have the same opinion. It is also tiring for people to say it is too “old school” to use the 1/4 turn back method. These are good reasons – easier to check with out damaging the valve and in no way does it lessen the amount of air flow though the valve.

    • Jesse Iacono
      Jesse Iacono says:

      Hi Steve,
      Thank you for taking the time to read and provide feedback on the article. I think that your opinion is very interesting, showing things from the point of view of the repair room. Although I have also spent some time working on equipment, it would not amount to nearly your 33 years! I agree that applying excessive force to a valve and turning it past the point where it naturally wants to stop can be detrimental to the components within, but I am not at all endorsing that anyone do either such things. Misusing any piece of equipment will guarantee it a much quicker trip to the repair room. Even if adhering the the quarter turn practice, one could apply excessive force when opening or closing the valve. The main point of my article though, was to show that there is more uncertainty surrounding the quarter turn practice than with a straight up on or off mentality. I simply aim to transmit my opinion of the method that minimizes risk.

      • Nate
        Nate says:

        I’d always understood the quarter turn to be the preventative measure for an overzealous tank check from stripping the handle. Always thought it was pretty reasonable, and for the DM it is a quick easy check. Only way I can see this going badly is if you can’t remember which was your valves open (but then this is probably just one of your many problems).

      • Steve Prosterman
        Steve Prosterman says:

        Hi Jesse, Thanks for the thoughtful reply. I have talked today to Mark Gresham head of PSI and instructor trainer for many agencies and manufacturers of valves and tanks as far as inspecting cylinders and rebuilding valves. Mark agrees with me and states that modern valves now are fully open after only a few (2-3) turns. The stem that is easily stripped however is the same soft brass stem used for 30+ years and still does strip easily. Now I do realize the tech diving industry is pushing all the way open and there are more than one right way to do many things. I am fine with agreeing to disagree and also if a tank is privately owned and used with other very familiar with buddy procedures,etc. then they certainly are in their right to open “hard” open and will most likely not have any issues over time. With places that have multiple divers of mmany experience and training level tho I feel the 1/4 method does save valves and save dives from being aborted,etc. Either way it is a good discussion and certainly both side have some merit, but disrespect should not be shown for old proven methods. Thanks

  5. Steve Prosterman
    Steve Prosterman says:

    I also believe that with a good thorough buddy check the chances of any “only 1/4 turn on” problem should be eliminated. The problem has a better chance of happening though if there is no hands on buddy check of the valve. It is fine to agree to disagree but do not disrespect tried and true methods that have prevented problems for a long time. While double checking divers on boats in the past 33 years I have also found valves in all stages of being open from not open to half way to all the way so I believe in hands on checks by buddies.

  6. Theuns
    Theuns says:

    Fully agree with you on blasting the air caps dry, and I wish divers will stop that.

    On the quarter turn back I’m not sure if I wholeheartedly agree with you. Many people don’t know which way is open or which way is closed.

    Same for the confusion between left and right. With digital watches and clocks people are also getting confused with clockwise and counter clockwise.

    For someone confused between left or right, clockwise or counter clockwise, it can be a challenge to open the valve, let alone double check a buddy’s valve before entering the water.

    With a little force a tank valve’s handle can be stripped and making it difficult or near impossible to operate.

    Also a valve that is open provides maximum airflow long before the last turn is reached. Thus a quarter turn back should not impede air flow.

    But I’m always eager to learn and adopt safer techniques, and will research further.


  7. Neil
    Neil says:

    Thank you for the article and your opinion. I respectfully disagree on the issue of the quarter turn method. To say that your article does not endorse people misuse equipment is like saying you are not endorsing someone to make a mistake (a statement you made in response to another comment). While your article debunks the initial argument about the valve sticking open if jammed, you don’t address in your article the benefit of the reduction in equipment wear/tear with the quarter turn method. If you’re going to write an article with such an absolute statement as you’ve made and then mass email it, then please address all the pros and cons of your statement, as there are cons to it. I’d like to see an article that discusses the pros and cons of both methods. I find more issues with the always open method, which I taught for several years after reading a similar article, and very few issues with the quarter turn method.


  8. Chris
    Chris says:

    I also find the 1/4 turn back from open a logical operation. Having spent years servicing valves and working with students, I have regularly encountered valves stuck open by over enthusiastic operators. This is usually a result of inexperience so when they are trying to open a valve that’s already open for one reason or another and because its tight thinking its closed and trying to open it further. Usually having not checked their gauges after the initial check or if their kit is in good condition is still reading full pressure even when the valve is shut. The last thing you need is a valve stuck open when for whatever reason, (free flowing kit or burst hose for example) you really need to close it.
    On the back of the boat as the DM as you check your charges into the water a quick check of their valve before they take that big step goes like.. dose it turn backward and forward…It’s open good, or no movement… they have forgotten to check or open it.. stop them and sort it out.. no dramas, It happens even with experienced divers. We get perpetrators of these sort of mistakes (or no weight belt ect…) that on their next dive they have to wear a pair of obnoxiously bright satin boxer shorts… on the outside of their wet suit..:) I cant understand why people find it necessary to noisily dry their dust/moisture cap when with a little practice you can do it with virtually no noise.

  9. Darrell
    Darrell says:

    I worked for a Course Director, with years of experience, who broke apart a set of doubles to use as single tanks. This meant that one tank had a left valve and the other had a right valve. On her first tank she ‘opened’ it 100% then turned it back a quarter turn. Everything went fine. On the second dive she ‘opened’ it 100% then turned it back a quarter turn. However because it was the opposite valve, what she thought was a 100% open was actually 100% closed. So the tank was only a quarter turn open. She tested it before jumping in the water. All seemed fine. When she got a few meters down she found breathing got harder and harder. She ended up quickly calling the dive and heading for the surface.

    She never does the quarter turn back anymore.

  10. Neil
    Neil says:

    If the sound of gas escaping genuinely caused ear damage I’d be deaf by now. I’ve heard that sound a couple hundred times a day for 2.5 years and my hearing hasn’t diminished. And if you work on a boat you should be used to it. And if turning your valve back a quarter turn reduces gas flow you need a new valve. Or at least a new seat. In no way does this impede air flow. I turn it back a little just to verify that the valve is open. Corrosion can cause a valve stem to not turn very easily and if you go to open it and it won’t turn, you could mistakenly think that it’s on all the way, when in fact it’s off, which is dangerous. I get the impression that the author has virtually no practical experience with tank valves.

    • Jesse Iacono
      Jesse Iacono says:

      I think you may need to give the article a more careful read. Most of the claims you are making about what was said in this article are untrue or were adequately addressed.

  11. Pete
    Pete says:

    I’m sorry but i have to disagree with both of the points you have mentioned. The blast method to clean a dust happens after a dive when everyone is doing it and it is therefore not out of the ordinary situation which either alarms people or scares them. If the blast happens before the dive then obviously something is wrong but after??????
    With regards to the 1/4 turn, someone has already mentioned the Divemaster part about them checking a tank is on. If you leave a tank 100% on, maybe it feels like a tank is off and therefore trying to turn it on can damage the thread. A 1/4 turn from the 100% on position does not reduce the valves effectiveness to deliver air in any which way.
    Obviously you are entitled to your own opinions and can teach or conduct your own equipment set up or breakdown as you see fit but to say other are doing it wrong and publish an article about it….? Honestly thought I was going to read something worth while.

    • Andy Higley
      Andy Higley says:

      Wow…common sense. How to make a quarter turn into a mountain ! Some people have too much time….I survived 1000 quarter turn back dives…but I was old.

  12. Red Godin
    Red Godin says:

    As a cave Diver we always open valves all the way, period. As a Divemaster in the Northeast I open my passengers valves all the way. Take 3 deep breaths while looking at the SPG before getting in the water.

  13. Pete
    Pete says:

    Looks like everyone out there has their own opinions and they should stick to them. Whether your a cold water, cave diving, tech diving hero or just a warm water plastic card carrying fun diver, do what you believe in people!. Lets just remember we have an amazing common ground. We love to blow bubbles!!!

  14. juan
    juan says:

    This article was written by someone with zero experience in diving and with no clue of what he is talking about. By blowing u cant clean some dust caps properly unless u r superman and who carries a towel just for the dust cap??
    If u press the dust cap against the valve when u r drying it, it doesnt make much noise.
    And the second thing, i had a tank valve that got stuck after a dive for not turning it back a quarter turn after an ignorant instructor told me not to do it. We had to empty the tank to be able to close it. If its only a quarter turn on and u breath through both 2nd stages at the same time with your buddy, the needle goes down!

  15. Rob Branch
    Rob Branch says:

    I have my own personal reason for not drying the dust cap with tank air. 25 years ago when I was a newbie diver and using this practice I had a tiny speck of sand lodge into my eye. I didn’t notice until the next day when I closed one eye to sight down a line (I’m a carpenter) and my vision was blurry. My vision is okay but I have a permanent red spot on my eye unless I get chose to get a operation. I’m sure I’m not the only person that this has happened to since the air exits pointing upwards at ones face.

  16. Kevin
    Kevin says:

    As a fairly experienced diver, a technical diver and a cave diver, I also eschew the 1/4 turn philosophy. That is what I was taught 30 years ago but with experience and more advanced training I no longer do it. My valve is either on or off, no halfway measures. In an emergency situation, if i needed to turn off a valve, I do not want to get confused turning it the wrong way. Task overload is a very real issue in tech diving, and anything that mitigates this is a good thing. For overanxious newbies that might tend to overtighten the valve, it seems like a good strategy, but one that is discarded as ones experience increases.

  17. Mike A
    Mike A says:

    Good article and while I do not disagree with any particular point, I was trained by ex-Navy frogman. Yes, I’m old :o) The reason they stated for the quarter turn had nothing to do with sticking valves but more importantly as an added LAYER of safety.
    If Neanderthal Man had overtightened the valve in the closed position, another diver, not near as strong or child diver, could twist the valve counterclockwise and assume the valve was full open. By doing the quarter turn, ANY other diver, double checking your gear would twist the quarter turn to the full open position and know it was open. If other important gear checks were missed, it lessened the likelihood of a mishap. We have all watched inexperienced (and sometimes seasoned) divers miss important gear items. Dive boats can be very busy places. Why not stack the deck in the diver’s favor.

  18. Gavin
    Gavin says:

    nothing better to write so re-gurgitation of the billion other articles written for the same result…another online war with people that know everything.
    Next article….carry a dive knife or not?….. woop, here we go!

  19. Buzz
    Buzz says:

    If your gauge floats with 1/4 turn back from full opened, your gauge needs maintenance or you need to change gauge brands.

  20. Scuba.Gee
    Scuba.Gee says:

    I used to teach the quarter-turn method, then I went tec. In tec the quarter turn is an absolute no-no. On is on, off is off. No confusion during task loaded emergency situations. I have also asked many instructors why they teach the quarter turn and have been given a myriad of different reasons, very few of which make much sense. It just seems to be that is what they learned to do, so that is what they teach.
    However I’ll blast my dust caps dry every dive…if done correctly it is quiet and is effective at drying the cap. Never lost an o-ring doing it, never lost my hearing, and don’t see any reason to stop doing it now.

  21. Tom Magee
    Tom Magee says:

    Any valve that is more than 50% open will perform the same as if it is 100% open, IME. What I hate is when some wannabe Hercules has tightened a valve so far open you need to get a pair of channel locks to get it closed. This applies to all cylinders that hold compressed gas. I work in an industry where I have stacks of oxygen cylinders around. I never allow them to be opened more than 30% in the event something bad happens and I have run to one of them and shut them off. They flow the same as if they were opened 100%.
    That said, I never really worry about where the valve on my dive gear is because I can reach it when wearing my equipment. Yes..I have jumped in the water with my air off a few times in the past and reached up and over and turned it on. No big deal, IME. Everyone should have the ability to manually inflate their BC and the skill to remove or don their gear in the water or they shouldn’t have and C card….right? I also don’t mind the clowns that blow dry their dust caps though I don’t do it myself.

  22. Ahmed
    Ahmed says:

    Even though the quarter turn back seems like an “antiquated” habit, it is indeed still useful in today’s gear, tank valves could stay in service for as long as 10 or 20 years, provided that they are periodically serviced and tested, and no matter how reliable they are, older valves could still jam if fully opened and then counter-pressurized under water. I have seen it for myself.
    Also, even if the valve doesn’t jam, the plastic handle of the valve itself could break lose and start spinning in emptiness without actually turning the valve off, and you can easily avoid applying pressure to it and causing this if you do the quarter turn back rule by habit.
    While the hazards of doing this are also valid, they can be completely avoided if you do proper buddy check before diving, which is not only to test the air by taking a breath from your regulator and watching the pressure needle (which is useful to test the regulator itself and not only the valve), but by letting your buddy make sure themselves that your tank is fully opened like what any responsible buddy would do.

  23. John Miller
    John Miller says:

    Wow, lots of opinions and disagreements. Been diving since my first c card from YMCA in 1973 in Maine. Own a dive shop and repair a lot of equipment as well as teach. Have done my own buddy check and then had boat DM “check” my air only to get 15 feet down and have to have my buddy turn it back on due to DM having turned it off. Always put second stage in mouth, look at pressure gauge as you draw air to see if needle moves. Sure sign your air isn’t on all the way. I posted earlier, I teach turn it on all the way gently and use your breath for clearing water from 1st stage and cap. Then shake excess water from 2nd stage and octo ?

  24. Nigel Cox
    Nigel Cox says:

    As a diver of 46 years experience and supporter of the “quarter turn back” procedure could I suggest that when checking a fellow diver’s reg is open it is a much easier, quicker and more assuring practice to turn just that residual 1/4 turn on and then back off, and I KNOW that the valve is now (effectively) fully open and it takes no time at all. Conversely, if an over-zealouis diver had previously turned the valve off so hard that it was very difficult to open, the ‘checker’ (especially a less experienced one) could mistakenly believe that the valve was fully open because they couldn’t open it any further when it was, in fact, fully closed. Of course this would be revealed by the pre-dive breathing check but it does remove one possible error – and I’m all for that.


  25. Andy Owens
    Andy Owens says:

    Disagree with the “quarter turn back part” but as a person with the disorder called cochlear hydrops, which gives you a sensitivity to load noise, especially high frequency, I HATE being the blast crap, so completely agree. As far as quarter turn back, I once saw a very, very experienced cave diver, about to leave for a body recovery dive, completely twist off a valve knob on a stage because it was “hard open”, delaying the departure of the team, ruining the valve, etc. I pulled another tank from my truck and replaced it. As far as DM’s on a dive boat doing a final check, when they have to twist the valve hard in the open direction it is hard on the knobs and to close it a bit, then open it hard back, also hard on the valves. Just my opinion.

  26. Anton Goodman
    Anton Goodman says:

    Amusing. My TDI instructor taught all of these things. Make me wonder what else was left out or changed.

  27. J
    J says:

    I had a person kindly check my valve (which was fully open) As I walked to the dive platform. Without telling me, they assumed my value was closed (no quarter turn) so they kindly closed it and then opened it a quarter turn. All without me knowing as I walked on a pitching boat. I discovered this at about 50ft down when the slightly opened valve could no longer supply my gas needs. I had to chat with the people on the boat afterwards to determine how my valve got closed between my checks and my 8ft waddle to the back of the boat.

  28. Paco
    Paco says:

    Silly article. If someone wants to use pressurized air to dry their gear, who cares? And if someone wants to turn their tank valve back a bit, who cares.

    Focus on what’s important, not this pedantic shit.

  29. Rick
    Rick says:

    To be honest and base on my experiences, the reason I teach opening the valve all the way and turn quarter back is to make sure new divers not accidentally broke the valve after dive. Most of the new divers got confused which way to turn off or on after the dive. So the quarter turn back is to prevent them from wrongly turn. I always told my students to make sure to ask me if they forgot or confused which way to turn. And some students would open all the way with full strength (over turn) that accidentally made the valve mechanism inside or screw broke and made the air flow without being able to turn in back off. Some even over turn when close the valve and made it unable to open again.

    Regarding using the air to blow off the excess water…well…most people not close enough and they open the air way too much. But i do agree about using dry cloth to dry up the dust cap but it will depending on situation.

    Well its been a while…Im an inactive teaching for almost 6 years so I dont really quite know any new changes. Really miss good old days…meeting new people. Laugh crazily…enjoying the “cough” views…but dont really mind learning more and more knowledges in case I go back to Diving World. Really appreciate this article and all the comments. Its nice to read other people experiences and experiments.

  30. Nicole
    Nicole says:

    As a ye olde diver/instructor, I was taught these 2 habits, and they are ingrained in me. However, I recognize times change. So I teach both to my students. I do NOT allow my students to blast the air dry method and if they can’t get it, I just say stick with towel/tshirt method. One thing I do emphasize is that pick one of the methods and stick with it. Another thing I emphasize is you check YOURSELF that your air is on THREE times before you jump in. Once when you check your air after assembly, again after the dive briefing and AGAIN just as you kit up. I’ve had my air turned off by well meaning staff (luckily I’m flexible and can turn it on by reaching back, but it’s a shitty thing to have happen). You don’t let anyone else pack your parachute…so to speak, ya know?

  31. Ian McLeod
    Ian McLeod says:

    Yes the air blasting drying is annoying, but the 1/4 turn back is sensible
    Anyone who has serviced a valve knows how they work, and a 1/4 turn is not going to impede air delivery.
    I have had valves stuck open, because they were forcefully fully opened
    The last time was when a “helpful” dive master checked my tank for me

    so I practice the 1/4 turn back and don’t let anyone touch my gear..


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