I had the exact scenario happen to me on a liveaboard in Maldives. The valve was in need of service to begin with and was extremely stiff to open and close. I always do a pre dive breathe and fill my wing before before jumping. All was good. What I didn't realise was the deck hand was doing the "quarter" turn back while you were just about to jump in. At the surface I had my reg and took a breath as I started to descend. About 20' there was nothing. Everyone else was descending so I couldn't reach out to get a reg so I just swam up instead. I'm an experienced diver but even though I wasn't that deep I was pretty stressed in those few seconds. I knew I had to be ready to orally inflate when I reached the surface. I checked all my gear and reached back to check the tank valve, sure enough it was off 🤬 I opened it and dropped down to catch up with everyone. Back on the boat I told the guy don't ever touch my gear again. He didn't understand English so I just my it clear as I knew he was only following directions from his boss and probably didn't know any better. Well on the second dive my son was ahead of me on the deck and the guy turned his valve back. Not a quarter but like 2 full hand twists. I yelled at him and warned my kid to check his gear again. My biggest problem with the whole thing was that I'm an experienced enough diver to have the awareness and composure to deal with the situation underwater and get my self to the surface as safe as possible. There were a lot of seasonal/vacation divers on board who could have easily been over weighted and not able to swim up like I did. They would have been hitting the inflator to fill their BC while at the same time sinking deeper. There was no body close to get assistance from because everyone was descending and we all know there's a lot of separation there until everyone gets situated at the bottom. It could have very easily been a drowning situation. Anyway, Long story but definitely a good reminder to always double triple check your own gear and don't let anyone mess with it.
Deckhands should be getting their hands chopped off for touching people's valves without permission. So many diving accidents happened because of this.
As a divemaster there's no way I'm letting you off my boat without me checking your air myself. I do a quarter turn forward then back to fully open so I know it's not just stuck but I have no clue how someone could be so dense as to turn your air off and call themselves a dive professional.
Maybe Alec Pierce's video on this (and UA-cam scuba channels) saved my life. I just did my 40M dive in my deep diver course last weekend with the valve only a quarter open (actually less because I only open it until theres no resistance). I checked my SPG at around 30M and as I breathed the pressure would drop from 190 bar to 75-ish. Luckily I breathed while checking the pressure and my instructor quickly saved the day when I pointed to my valve (I didn't want to turn it the wrong way). I am also lucky I had watched the Alec Pierce video on this a few years ago and (although I forget most details out of the hundred or so scuba videos I've watched) for some reason I have a crystal clear memory of the visual of SPG needle dropping as you breathed and immediately knew what the problem was. Needless to say my air use was higher than expected for that dive. What I think happened was one of the boat guys (Chalong, Thailand) was checking in case my cylinder was empty (to refill between dives) and opened the valve (I turn it off after setting up and release pressure from my octo so its 0 on the SPG) and before diving I stupidly turned it the wrong way and then a tenth or so of a turn back. I was taught the quarter turn back on my OW 2018.
I got OW certified December of last year, and they taught us the 1/4 turn back!!! Thanks for actually educating me about what’s going inside the cylinder valve…
Same here. I was like "hmmm..." at that cause I read a bunch of scuba experiences (of admittedly bad ends) of people who died from that. "Quarter turn back" was more like "most of it" and...yeah. No bueno.
Well damn... James, you just disproved the old adage, "You can't teach an old dog new tricks." Well, in the 70's I was taught, AND I taught, open valve fully then 1/4 turn back. Well, now that you have re-edgu-ma-cated this old fart, I will never quarter turn back my dive tank. Great video as always. Keep up the great work James.
i agree coz i m always confused when people ask me to confirm their tanks being opened. but now i m doing theory of dive master. one of the question: True or False: To ensure the air is on and to relive pressure on the valve's o-rings, many diver's turn the cylinder valve knob back a quarter-turn to half-turn after opening it all the way. Answer "As a matter of routine most divers then turn the knob back a quarter-turn to half-turn (clockwise) to ensure that the threads of the valve's handle remain engaged, and to relieve excessive pressure on the valve's interior o-rings. The correct answer is 'True'."
James, thank you for bringing up and explaining the 1/4 turn. I see it way too often out there. My instructor taught us the 1/4 turn years ago, but he was over 70 years old and had been diving a long time. I never teach it, although i do teach the bit about watching your SPG when doing your pre-dive checks and even demonstrate the needle drop that occurs. As always an awesome video, thanks for all you do.
Thank you James! Such a great explanation of a valve function. I was taught that the quarter turn back was established because in cold water diving in an excessive gas loss situation (free flow for example) the valve would get so cold that the high pressure seat can freeze shut and you wouldn't be able to close it again. Thanks for teaching us better and from now on I will keep the valve all the way open. It already happened twice that my tank was open and someone closed it, then only opened a quarter turn. That's why we should all do thorough buddy checks. Easy fix on the surface, rather than stressful situation underwater.
I never realized how complex the cylinder valve was. I learned the 1/4 turn, but my class was decades ago. I didn't think about how dangerous this was, though. Great video.
I had the quarter turn back from closed thing happen to me in 2017. My air cut off at about 70 feet, and I nearly drowned. Thanks for bringing attention to the issue!
Great video James! Thanks for the three finger opening tip. I tried it with all my tanks and thankfully I'm able to open all of them! I'll open them like that from now on. One thing to mention; I tried breathing from my tanks with a quarter turn open from the closed position and the SPG didn't fluctuate for most of them. The valves that didn't fluctuate were a dull silver (ones from the factory) and the only one that did fluctuate was the chrome silver valve. I've been told that my chrome silver valve opens slowly thus releasing the gas slowly from the tank whereas the dull silver valves open the tank very quickly. If someone has the dull silver valves on their tanks, they might not notice on the surface but at depth it might be too late. Lesson to be learned: never trust anyone except yourself! Should be the one to test your own equipment! I'm looking forward to watching more of your videos!
Hey James. Thanks for your vids. I really enjoy them. I learn a heap from them! I started to dive at 17, stopped for 45 years and started from scratch again 4 years ago, clearly I'm an old bloke. Lovin' it. Thanks for your commitment! Crouchy in Oz.
5:20 Tell this to the commercial diving courses where they still teach it. You close it a quarter turn so a second person who checks it can feel it is opened. Otherwise somebody might think the tank is still closed, and they will apply force to try to open it.
I've had so many arguments about this including people rejecting the DAN research and article from a year or two ago. I'm really glad to see someone approach this from the "here's what's inside" view. Keep up the amazing work!
NAUI needs to update their open water course training. I just recently certified and the on line portion still says 1/4 turn back. My instructors were great and said same as you, absolutely not! Wide open or completely closed. Love your videos.
Thanks - Just found this video and it's really interesting as when I did my Open Water Course just a few days ago, (end of May 2024) I was told to do the quarter turn back thing. Have sent a link to your video to the instructor who taught me and will be interested in what she says in reply, as it's over two years after you made your video...
This makes sense. I learned in my OWD to rotate the valve not quarter but half circle back after being fully open. That makes lot of confusion at the last pre-dive check, wondering is it open or closed. Thank you for this advice.
This was great James. I'd never service my own stuff, cause you know.... but it is great to see what should be done, and what to ask for at the point of service. Found this super useful. 👌
While diving this summer I had a rental cylinder and regulator. The valve was all the way open but the needle dropped and got back up again. The divemaster told me that it's normal on their cylinder/regulator. I don't know why this is normal but I had no issues during the dives.
Hi James, Congratulations on surpassing 50k subscribers! What a testament to your team's efforts! Thanks for this cylinder valve video, informative as always. Very much enjoying your reco'd read: G. Lock's
Thanks for updating me for free :) I'm not even sure if I got the wrong way of opening the cylinder from my instructor or later from some random dudes on a dive boat 😅
But you didn't mention the good ole J Valve which I have on my tanks ! They are still working great after 43 years of use ... and Yes we were taught to 1/4 turn and I still do and have never had any problems doing it .
I was doing my deep dive cert and I had always learned 1/4 turn. Let me just say, when I got to 80’ and I couldn’t get air to flow evenly and the gauge was moving as described in this video, it was my instructor who saved my bacon. Seriously, ALL THE WAY ON OR OFF. No quarter turn… I could have died
As a diver and a motor bike rider I just want to say we only use 3 fingers on the throttle as well lol. Wrenching on the throttle is a good way to do involuntarily cartwheels
Good to know. I got my open water only last year and was told to quarter turn as-well, I guess the instructor simply wasn't up to date, the tanks certainly didn't seem THAT old.
Huh, I always understood the half turn as a way to prevent people from wrenching on the knob. If the tank is closed a little too tightly, it can take some effort to open. This state can be mistaken for a tank that's already open all the way. The half turn of give tells whether it's been opened or not.
How sure are you about the "neoprene" seals? I've never analysed the material, but I would guess that the white seals are PTFE or Teflon rings, that do not have sealing function but as a gliding point for the outer one and backing up function for the actual o-ring on the inner one.
They are teflon/PTFE plastic! They are there because the cross drive spindle sees the tank pressure when the valve is open and a 1st stage is seated, which means it experiences a relatively signficant axial load. That load is reacted in the "slippy" washers to enable the valve to be turned without too much friction. When the valve is shut and the 1st stage depresurised and removed, then the threaded valve stub with the molded in PTFE seat seals the tank exit tapping, and there is no pressure on the pass through.
Good explanation of why not 1/4 back. Many divers still do it. And recently a woman at 20m learnt she couldn't breathe... But I think you are wrong about a burst valve and spinning. This valve has two holes on opposite sides exactly to avoid even spinning.
I stopped diving a very large operator in Key Largo after they almost killed me with their 1/4 crap. Short version, broke down my doubles into Singles, doing a 120 footish dive in Largo, Tank was all the way open. Somewhere around 75 feet I am getting no air. Switched to pony, asked buddy to check tank, he opens it up, and we finish our dive. The DM had closed my valve then 1/4 my tank when pushing me in, yes, he admitted to it when I surfaced. He had no idea what a reverse valve was. I had told a different DM before jumping in, do not touch my gear.
Yes, the main original reason for the quarter turn was the potential stress on the valve components, and this was very useful to see everything laid out. But there is another reason. I have twice seen someone check their valve and jump in, only to find it was actually completely shut. They had tried turning it anticlockwise, it didn't move and they assumed it was fully open when in fact it was just very tight shut. Everyone should of course take a few breaths and watch their SPG during their checks but some less regular, less 'committed' divers will sometimes in their excitement forget. But if the valve still has that last bit of movement you can immediately tell it's as it should be. And as to why you shouldn't do it, I've never ever seen anyone turn the valve the wrong way, closing it and then cracking it open.
In relation to your last sentence... i've experienced this.... Girlfriend turns on her tank goes to prepare mask... boyfriend comes along, closes tank, opens a quater turn. Girlfriend is OOA at 6m with 70 bar in the tank..
it happened to me. My insta-buddy closed my valve upon request to double check it's position, than disappeared in the first 2 min into the dive. I was out-of-air at 10-11m depth, tried octo (did not work) and had to do my first ever CESA to meet observant instructor on the surface who opened valve for me. Learnings taken 1) always fully closed/open valve position 2) nobody messes with my valves 3) always be able to reach your valves. That was happening more than 10 yrs ago but i remember it very well.
It happened to my friend. Either she or the boat crew didn't know left from right and closed the valve, then quarter turn open. I noticed her concern under water at 30m and she showed her SPG needle moving when she breathed. Was a quick fix of course but we definitely did our buddy checks from then on.
James, another great video. Thank you for all the content it truly is helpful. As others have mentioned I was taught to quarter-turn as well in 1978. I'm curious what are your thoughts on how new a valve needs to be not to be affected as old valves were thought to be.
I always enjoy your videos. Always very informative. However, I'm a quarter of one turn guy. I've been doing it since 1997. One quarter of one turn is not going to restrict air flow. I do this for one simple reason...so that the valve doesn't bind. Every time I'm on a dive boat, the DM checks every diver's valve before they jump in and crank it fully open and every time I get out of the water and go to turn my tank off, the valve has binded due to thermal contraction. Tank sits in the sun for hours warming up, valve cranked open all of the way, then quickly gets cooled in 53* water. One time, I had to take a strap wrench to it to so I could close it to get my reg off so that they could refill my tank before the next dive. And yes, my tanks and valves are serviced regularly. I was a nuclear power plant operator and operated a steam plant with hundreds of valve. You ALWAYS close a valve one quarter turn to prevent binding from thermal expansion/contraction. EDIT: For those that have no problems with stuck valves and don't like to close 1/4 turn of 1 turn, when you turn to full-open, be sure to just use your fingers and NOT cranked open like you're trying to tighten a bolt. I've seen DM's and divers' buddies crank valves open using their whole hand, which gives them more leverage making it more difficult to sense the amount of torque being applied.
Someone said it before, all other industries using pressurised gas tanks use a quarter turn. For good reason. Since most divers do not own their own tanks, and dive centers use their tanks til they don't pass hydrostatic testing, anymore. You probably will dive with tanks that may be 20 years old. The servicing of tank valves with the current low pricing in the industry is not done on a yearly basis. It is done when the valve actually does not work anymore. These are just the simple facts of reality. So quarter turn is still a must. The inherent point here is training, and proper check prior to a dive. (No shortcuts)
If i buy a 3442 psi steel scuba tank with pro valve fitting and i screw out the din screw to make a din fitting will the tank din thread be 5 or 7 threads deep.now if i buy a din fill station in the uk will it fit regardless if the male din adapter on this fill station is 5 or 7 threads deep thanks
An other version of the "Wide open, and then closing 1/4 turn" - The idea is that if a buddy is out of air and the buddy is hanging on your octo - then it is very fast and easey to feel (with 3 fingers, for both divers) if the valve is loose (open). If it is loose then abort the dive at once, together. You might be out of air soon, too!
I’ve messed up a few times where I only opened the valve a 1/4 turn. I didn’t find out till after my 140’ dive was complete. Also, I back the knob off just a smidge from all the way open. There’s been too many times where it’s all the way open and I couldn’t close it during a valve drill and had to have my buddy bust it loose. 1/4 turn is too much.
What I do is, I open the valve fully and then loosen it, so it screws easily in case I need to close it. You don't want to be wrenching your valve if it's opened all the way and then some when you get a freeflow.
Hi James, Great Video series. I just purchased a new Catalina 80 Alu tank where I want to replicate my old US Diver 80 Alu from the 70's with new decals. Should be a conversation piece. Here's my question: The original USD J-valve is cosmetically in great shape and still on the old tank with 200~300 psi still in it and has not been used in 30 years. Can its J-Valve be serviced and used on the new tank?
@@nicwelch simple really, the entire gas using world is using the quarter turn back, so why should we change an international industry standard on the usage of gas tanks. Then furthermore, totally open works in a perfect world where all tank valves are new, but they aren't. I think the debate on tank valves should not exist in the first place, we have a set standard, it has worked out well so far.
@@oceanroamers To be fair, that's just not good enough. First of all the entire gas using world does not do this, at least not in welding. Full open or nothing, that's standard where I live anyway. Second, just because it's always been done a certain way does not mean there isn't a better way. I do understand thermal expansion being a problem when you go to shut the valve and it now being too tight but unless you're cranking on it with your hand it should be fine fully open right?
Sadly, during my last liveaboard, I've had to do the quarter-turn - otherwise after the dive the valve would only close with a wrench. Seems like that tank was in dire need of service.
Was it the old style pillar valve? If so that design is exactly why the quarter turn used to be done. They would not close after using the tank, and the only option was a wrench or blowing an o-ring.
The one thing I found that you have to watch out for is a dive guide who checks your valve as you are getting ready to do a giant stride off the boat. I have seen some actually test the valve then do the quarter turn back. So just be aware of that so you can tell the dive guide to not do that for you.
@S M How many dives do you have under your belt.? Dm's check beginners tanks,because if they didn't a lot of people would be submerging with their tanks not fully open.That said I only think it is necesarry during training.
@S M I've also seen it done like that and no I don't agree with it. As an instructor I have to be self sufficient, and one check i always do is the spg while taking a breath
@S M Yep, I've done around 3000 dives, I worked in the industry for 12 years and might dip my toe back in at some stage.Dived with a few military divers,they were obviously very good.
Nice video, it would have been better by comparing the old design with the new one. A question would be how to you know if a cylinder is the old design or the new design, in particular when you are in remote locations where they have very old stuff. Would you leave the valve open all the way in the old design as well? On another topic, is that a Teric? what happened to the Garmin?
The old valves are really old by now and I don't think any would be in use by a commercial dive operation. I think it was back in the 1970's when the upgrade took place. Hence, the 1/4 turn has not been needed for longer than most divers have been alive. I'm pretty sure Alec Peirce's UA-cam channel talks about this in one of his tank valve videos. IF a commercial dive operation was still using valves so old they needed the 1/4 turn, I would not walk but run away.
@@jeffworst9939 Thanks for the clarification. I was naïve by thinking that the training agencies would have updated their protocols in 50 years... haha. We just need to re-train ourselves. I hope I'll remember this next time I go diving... what was the thing about old dogs and new tricks...
Does a quarter turn back from "full open" actually hurt anything? For all of us who learned that particular rule decades ago, I've always done it. Never created an issue with my gas supply. And after viewing thousands of videos, blogs, etc., you're the first person I've ever heard saying don't do it. My "forever buddy" (wife) quit diving years ago, so I'd say 80% of my dives over the past 15 years have been with a DM. None of them, during the pre-check, have ever said anything about that. Shower knob valves are nowhere near as complicated as dive tank valves - but one of the reasons a valve stem on a faucet begin to fail is because people (my wife, LOL) cranks on that knob as hard as she can when turning the water off. The valve stem washer gets worn out. So I guess I just don't get the harm in a quarter turn back from fully open, especially considering it took 2-3 full turns to get to full open to begin with.
Never touch another divers gear unless it's your dive buddy and you have been asked. As a dive master I did a lot of work on Southern California Liveaboards. I promoted the take a breath while watching your regulator. I started doing that back in 1988. Always put people in the position of self reliance. Don't touch other divers gear even if you are an instructor or dive master or boat operator.
Australian standards for gas cyclinders requires a half turn back to avoid seizure in an open position. Sighted from BOC standards Australia- Guidelines for gas cyclinder safety.
When I take a new diver to Peacock I like to tell them how this is where Sheck found himself out of air due to the quarter turn, while being upside down and stuck in the crack.
Good one and I have seen many issues with valve operation in the past. Valves only opened a bit that didn't deliver at depth, "friends" thinking they are being helpful by touching your valve. I can see from the comment below that there may be some confusion about "1/4 turn". You spoke about having the valve only 1/4 turn open, but there is also the practice of "opening the valve wide open, and then closing 1/4 turn". There is some logic to this and it is the way I have done it with all HP gas cylinders. If you open it wide and turn it back 1/4, you will always know what position it is in when you check it later by giving it a quick test. If you open it 100% and maybe a bit too tight, then there is a chance that when you try it, you will torque it open even more and stress the seats etc. Having said that; there are a lot of experts that say open the valve all the way.
Hi Barry, I'm going to respectfully disagree with you on this one and side with James... Open or closed----nothing in between. The issue is when you think you've opened it 100% and then 1/4 turn back when actually you closed it 100% and done the 1/4 turn back. Now it's open just a fraction. I have filled 10's of thousands of tanks over the years, but, being human, can still have a brain fart. I don't think that anyone has perished from having a tank jammed open. Have a very pleasant evening.
I always turn my valves all the way open and half turn back. The reason for this is that I had so many stupid divers not know how to shut off thier tanks and rip the valvle threads. Its safe, turning half a circle wont prevent air flow.
Had a rental tank I couldn’t shut off because the square drive was gutted. It had just enough left in it to open the tank. Everybody looked at me like I was a moron venting out the entire tank on the dock to switch it out. One guy said just dive it… pass.
July 2024: to your point.... just had a 77 YO diver die while shallow in a quarry dive in KY and it was found that his tank valve was only opened 1/4 turn. It is suspected that he confused "righty-tighty / lefty-loosy" and instead of opening his valve some time after his equipment was set up, he shut it and cracked it open 1/4 turn. FULLY opening the valve is the ONLY way. Tragic....
Loving your channel. But this time, erm. No. You open your cylinder all the way, and then 1/4 turn it back. No mechanical reason. Simply: if the knob turns (three fingers, no effort) a bit in both directions it's open, if it doesn't turn at all it's closed. Then again, never underestimate the power of the "silly people"... ;)
Taught 1/4 back in 1980s. The rationale that valve can get stuck open made sense. So applied the principle to all valves - water taps, gas cocks, etc. Never had a problem with valves I’ve opened but have come across many stuck open valves due to temp change contraction/corrosion from not being moved over a long period of time. However, was recently advised to only open LPG gas valves 3/4 of a turn at most. Sufficient to open the valve for LPG gas to flow but able to be closed with one twist of the wrist in an emergency. So it seems, full open for scuba valves, 1/4 back for water taps & only 3/4 of a turn open for LPG gas.
Wish they would have named the DIN adapter a "DINnut. I remember when the 1/4 back was gospel - never liked it for the 1/4 turn open reason. 3 thumbs up from the mutant divers!
Something to add. I do not see many people, especially with rental gear, ensuring they can reach and operate their tank valves while diving. Not needing someone's assistance to open and close the valve can be extremely important. If everyone could reach their valves and know which way is open and closed, this point about the 1/4 turn becomes less relevant.
You said a bunch of people died because they only turned their cylinder on a quarter of a turn. fair a statement. However that has nothing to do with fully on and back quarter of a turn. By the way I was trained half a turn. Typically a dive cylinder valve takes around 5 to 8 full turns to turn on and off. 1/2 a turn back is not gonna cause I shut down. Have a look at the construction of the valve. I cannot see how that High pressure Teflon seat can have a shut down because of a half turn. It physically cannot happen unless the valve spindle is turned. You are wrong about an incidental shut down resulting from a half term. I would be happy if you explained how the Teflon seat could do another 5 1/2 to 7 1/2 turns to shut down without the spindle been turned by other means.
Burst disks should be built into fill whips rather than scuba cylinders. Why should I die in a cave because my burst discs have corroded to prevent an accident in a fill station? It's a flawed design that makes no sense.
@@ppo2424 You really need to back your statement using logic reason and evidence, as this gentlemen did. I don't care how many dives you have under your belt either.
I had the exact scenario happen to me on a liveaboard in Maldives. The valve was in need of service to begin with and was extremely stiff to open and close.
I always do a pre dive breathe and fill my wing before before jumping. All was good. What I didn't realise was the deck hand was doing the "quarter" turn back while you were just about to jump in. At the surface I had my reg and took a breath as I started to descend.
About 20' there was nothing. Everyone else was descending so I couldn't reach out to get a reg so I just swam up instead.
I'm an experienced diver but
even though I wasn't that deep I was pretty stressed in those few seconds. I knew I had to be ready to orally inflate when I reached the surface.
I checked all my gear and reached back to check the tank valve, sure enough it was off 🤬
I opened it and dropped down to catch up with everyone.
Back on the boat I told the guy don't ever touch my gear again. He didn't understand English so I just my it clear as I knew he was only following directions from his boss and probably didn't know any better. Well on the second dive my son was ahead of me on the deck and the guy turned his valve back. Not a quarter but like 2 full hand twists. I yelled at him and warned my kid to check his gear again.
My biggest problem with the whole thing was that I'm an experienced enough diver to have the awareness and composure to deal with the situation underwater and get my self to the surface as safe as possible.
There were a lot of seasonal/vacation divers on board who could have easily been over weighted and not able to swim up like I did. They would have been hitting the inflator to fill their BC while at the same time sinking deeper. There was no body close to get assistance from because everyone was descending and we all know there's a lot of separation there until everyone gets situated at the bottom. It could have very easily been a drowning situation.
Anyway, Long story but definitely a good reminder to always double triple check your own gear and don't let anyone mess with it.
Wow, thanks for sharing. I'm glad that both you and your son are safe.
Deckhands should be getting their hands chopped off for touching people's valves without permission. So many diving accidents happened because of this.
As a divemaster there's no way I'm letting you off my boat without me checking your air myself. I do a quarter turn forward then back to fully open so I know it's not just stuck but I have no clue how someone could be so dense as to turn your air off and call themselves a dive professional.
@@tylerbaird7287 after the first time you touch my life support there will be a conversation, touch it again after that there will be problems
Maybe Alec Pierce's video on this (and UA-cam scuba channels) saved my life.
I just did my 40M dive in my deep diver course last weekend with the valve only a quarter open (actually less because I only open it until theres no resistance). I checked my SPG at around 30M and as I breathed the pressure would drop from 190 bar to 75-ish. Luckily I breathed while checking the pressure and my instructor quickly saved the day when I pointed to my valve (I didn't want to turn it the wrong way).
I am also lucky I had watched the Alec Pierce video on this a few years ago and (although I forget most details out of the hundred or so scuba videos I've watched) for some reason I have a crystal clear memory of the visual of SPG needle dropping as you breathed and immediately knew what the problem was. Needless to say my air use was higher than expected for that dive.
What I think happened was one of the boat guys (Chalong, Thailand) was checking in case my cylinder was empty (to refill between dives) and opened the valve (I turn it off after setting up and release pressure from my octo so its 0 on the SPG) and before diving I stupidly turned it the wrong way and then a tenth or so of a turn back. I was taught the quarter turn back on my OW 2018.
I got OW certified December of last year, and they taught us the 1/4 turn back!!! Thanks for actually educating me about what’s going inside the cylinder valve…
Same here. I was like "hmmm..." at that cause I read a bunch of scuba experiences (of admittedly bad ends) of people who died from that. "Quarter turn back" was more like "most of it" and...yeah. No bueno.
@@kylegrimm8808 Interesting. Yeah, I'd heard it specifically referenced in...I think welding comes to mind.
That's because the quarter turn is still valid, don't take this guys talk for being read.
Well damn... James, you just disproved the old adage, "You can't teach an old dog new tricks." Well, in the 70's I was taught, AND I taught, open valve fully then 1/4 turn back. Well, now that you have re-edgu-ma-cated this old fart, I will never quarter turn back my dive tank.
Great video as always. Keep up the great work James.
Same
i agree coz i m always confused when people ask me to confirm their tanks being opened. but now i m doing theory of dive master.
one of the question: True or False: To ensure the air is on and to relive pressure on the valve's o-rings, many diver's turn the cylinder valve knob back a quarter-turn to half-turn after opening it all the way.
Answer "As a matter of routine most divers then turn the knob back a quarter-turn to half-turn (clockwise) to ensure that the threads of the valve's handle remain engaged, and to relieve excessive pressure on the valve's interior o-rings.
The correct answer is 'True'."
As you said; 12 years ago I was tought the wrong thing, Thanks a lot James from now on · 3fingers to turn the valve and not a quarter backwards
James, thank you for bringing up and explaining the 1/4 turn. I see it way too often out there. My instructor taught us the 1/4 turn years ago, but he was over 70 years old and had been diving a long time. I never teach it, although i do teach the bit about watching your SPG when doing your pre-dive checks and even demonstrate the needle drop that occurs. As always an awesome video, thanks for all you do.
Thank you James!
Such a great explanation of a valve function.
I was taught that the quarter turn back was established because in cold water diving in an excessive gas loss situation (free flow for example) the valve would get so cold that the high pressure seat can freeze shut and you wouldn't be able to close it again.
Thanks for teaching us better and from now on I will keep the valve all the way open.
It already happened twice that my tank was open and someone closed it, then only opened a quarter turn.
That's why we should all do thorough buddy checks. Easy fix on the surface, rather than stressful situation underwater.
I never realized how complex the cylinder valve was.
I learned the 1/4 turn, but my class was decades ago. I didn't think about how dangerous this was, though.
Great video.
Thanks for the update,I'll be sticking to the quarter turn thanks
Thank you for that James, the more divers who know the full turn the better ... 👍
Jamesy, thanks for the free update. Brilliant explanation.
Best video on tank regulators I've seen! Tks and Congrats on the content!
A burst disc is fun experience had one this week 😎
Excellent instructional video James! Thank you!!
I had the quarter turn back from closed thing happen to me in 2017. My air cut off at about 70 feet, and I nearly drowned. Thanks for bringing attention to the issue!
Great video James!
Thanks for the three finger opening tip.
I tried it with all my tanks and thankfully I'm able to open all of them! I'll open them like that from now on.
One thing to mention; I tried breathing from my tanks with a quarter turn open from the closed position and the SPG didn't fluctuate for most of them. The valves that didn't fluctuate were a dull silver (ones from the factory) and the only one that did fluctuate was the chrome silver valve. I've been told that my chrome silver valve opens slowly thus releasing the gas slowly from the tank whereas the dull silver valves open the tank very quickly.
If someone has the dull silver valves on their tanks, they might not notice on the surface but at depth it might be too late.
Lesson to be learned: never trust anyone except yourself!
Should be the one to test your own equipment!
I'm looking forward to watching more of your videos!
Hey James. Thanks for your vids. I really enjoy them. I learn a heap from them!
I started to dive at 17, stopped for 45 years and started from scratch again 4 years ago, clearly I'm an old bloke. Lovin' it.
Thanks for your commitment! Crouchy in Oz.
Thanks for sharing! Dive safe.
5:20 Tell this to the commercial diving courses where they still teach it. You close it a quarter turn so a second person who checks it can feel it is opened. Otherwise somebody might think the tank is still closed, and they will apply force to try to open it.
Thank you for this helpful update! Ive been quarter turning back for 20 years! ❤️
I've had so many arguments about this including people rejecting the DAN research and article from a year or two ago. I'm really glad to see someone approach this from the "here's what's inside" view. Keep up the amazing work!
NAUI needs to update their open water course training. I just recently certified and the on line portion still says 1/4 turn back. My instructors were great and said same as you, absolutely not! Wide open or completely closed. Love your videos.
Thanks - Just found this video and it's really interesting as when I did my Open Water Course just a few days ago, (end of May 2024) I was told to do the quarter turn back thing. Have sent a link to your video to the instructor who taught me and will be interested in what she says in reply, as it's over two years after you made your video...
Awesome You answered a question I have asked many Instructors. But you answered it correctly and thoroughly.
This makes sense. I learned in my OWD to rotate the valve not quarter but half circle back after being fully open. That makes lot of confusion at the last pre-dive check, wondering is it open or closed. Thank you for this advice.
This was great James. I'd never service my own stuff, cause you know.... but it is great to see what should be done, and what to ask for at the point of service. Found this super useful. 👌
That was absolutely an useful video!
While diving this summer I had a rental cylinder and regulator. The valve was all the way open but the needle dropped and got back up again. The divemaster told me that it's normal on their cylinder/regulator. I don't know why this is normal but I had no issues during the dives.
Hi James, Congratulations on surpassing 50k subscribers! What a testament to your team's efforts! Thanks for this cylinder valve video, informative as always. Very much enjoying your reco'd read: G. Lock's
Thanks for updating me for free :)
I'm not even sure if I got the wrong way of opening the cylinder from my instructor or later from some random dudes on a dive boat 😅
Absolutely marvelous James.
Thanks for this video James. I was taught quarter turn back in just the last two years.
Thanks for the Explanation!
But you didn't mention the good ole J Valve which I have on my tanks ! They are still working great after 43 years of use ... and Yes we were taught to 1/4 turn and I still do and have never had any problems doing it .
I was doing my deep dive cert and I had always learned 1/4 turn. Let me just say, when I got to 80’ and I couldn’t get air to flow evenly and the gauge was moving as described in this video, it was my instructor who saved my bacon. Seriously, ALL THE WAY ON OR OFF. No quarter turn… I could have died
As a diver and a motor bike rider I just want to say we only use 3 fingers on the throttle as well lol. Wrenching on the throttle is a good way to do involuntarily cartwheels
Super valuable information!
Good to finally know the actual reason for not needling the 1/4 turn. Still seeing the occasional person do this.Thanks for the clarification!
Good to know. I got my open water only last year and was told to quarter turn as-well, I guess the instructor simply wasn't up to date, the tanks certainly didn't seem THAT old.
Huh, I always understood the half turn as a way to prevent people from wrenching on the knob. If the tank is closed a little too tightly, it can take some effort to open. This state can be mistaken for a tank that's already open all the way. The half turn of give tells whether it's been opened or not.
Great content, buddy!
I just got back into diving. I was taught 1/4 turn back. Good to know things have changed, and how to check with the breathing thing. Cheers james
Thank you!! Great tips and on the button
I thought we were getting Deco Procedures video today? anyway thanks as always!
How sure are you about the "neoprene" seals? I've never analysed the material, but I would guess that the white seals are PTFE or Teflon rings, that do not have sealing function but as a gliding point for the outer one and backing up function for the actual o-ring on the inner one.
They are teflon/PTFE plastic! They are there because the cross drive spindle sees the tank pressure when the valve is open and a 1st stage is seated, which means it experiences a relatively signficant axial load. That load is reacted in the "slippy" washers to enable the valve to be turned without too much friction. When the valve is shut and the 1st stage depresurised and removed, then the threaded valve stub with the molded in PTFE seat seals the tank exit tapping, and there is no pressure on the pass through.
Thanks. I needed to hear that
i like your non-ego, no bullshyte delivery maybe its the name james... good name
Good explanation of why not 1/4 back. Many divers still do it. And recently a woman at 20m learnt she couldn't breathe...
But I think you are wrong about a burst valve and spinning. This valve has two holes on opposite sides exactly to avoid even spinning.
I stopped diving a very large operator in Key Largo after they almost killed me with their 1/4 crap. Short version, broke down my doubles into Singles, doing a 120 footish dive in Largo, Tank was all the way open. Somewhere around 75 feet I am getting no air. Switched to pony, asked buddy to check tank, he opens it up, and we finish our dive. The DM had closed my valve then 1/4 my tank when pushing me in, yes, he admitted to it when I surfaced. He had no idea what a reverse valve was. I had told a different DM before jumping in, do not touch my gear.
Almost killed you, lol, being pretty dramatic there.
Yes, the main original reason for the quarter turn was the potential stress on the valve components, and this was very useful to see everything laid out. But there is another reason. I have twice seen someone check their valve and jump in, only to find it was actually completely shut. They had tried turning it anticlockwise, it didn't move and they assumed it was fully open when in fact it was just very tight shut. Everyone should of course take a few breaths and watch their SPG during their checks but some less regular, less 'committed' divers will sometimes in their excitement forget. But if the valve still has that last bit of movement you can immediately tell it's as it should be. And as to why you shouldn't do it, I've never ever seen anyone turn the valve the wrong way, closing it and then cracking it open.
In relation to your last sentence... i've experienced this.... Girlfriend turns on her tank goes to prepare mask... boyfriend comes along, closes tank, opens a quater turn. Girlfriend is OOA at 6m with 70 bar in the tank..
@@Aumscuba Definitely needs new boyfriend!
it happened to me. My insta-buddy closed my valve upon request to double check it's position, than disappeared in the first 2 min into the dive. I was out-of-air at 10-11m depth, tried octo (did not work) and had to do my first ever CESA to meet observant instructor on the surface who opened valve for me. Learnings taken 1) always fully closed/open valve position 2) nobody messes with my valves 3) always be able to reach your valves. That was happening more than 10 yrs ago but i remember it very well.
It happened to my friend. Either she or the boat crew didn't know left from right and closed the valve, then quarter turn open. I noticed her concern under water at 30m and she showed her SPG needle moving when she breathed. Was a quick fix of course but we definitely did our buddy checks from then on.
Great video.
James, another great video. Thank you for all the content it truly is helpful.
As others have mentioned I was taught to quarter-turn as well in 1978.
I'm curious what are your thoughts on how new a valve needs to be not to be affected as old valves were thought to be.
Me too in 1994 LOL
so from what time did the valves improve. I have a set of tanks from 2003 still good.
Brilliant video, except I would never reuse a copper washer.
"...suboptimal..." classic James
How to store our cylinders should we leave some pressure (how many psi is good?)in it so that humidity can not enter the cylinder?
I always enjoy your videos. Always very informative. However, I'm a quarter of one turn guy. I've been doing it since 1997. One quarter of one turn is not going to restrict air flow. I do this for one simple reason...so that the valve doesn't bind. Every time I'm on a dive boat, the DM checks every diver's valve before they jump in and crank it fully open and every time I get out of the water and go to turn my tank off, the valve has binded due to thermal contraction. Tank sits in the sun for hours warming up, valve cranked open all of the way, then quickly gets cooled in 53* water. One time, I had to take a strap wrench to it to so I could close it to get my reg off so that they could refill my tank before the next dive. And yes, my tanks and valves are serviced regularly. I was a nuclear power plant operator and operated a steam plant with hundreds of valve. You ALWAYS close a valve one quarter turn to prevent binding from thermal expansion/contraction.
EDIT: For those that have no problems with stuck valves and don't like to close 1/4 turn of 1 turn, when you turn to full-open, be sure to just use your fingers and NOT cranked open like you're trying to tighten a bolt. I've seen DM's and divers' buddies crank valves open using their whole hand, which gives them more leverage making it more difficult to sense the amount of torque being applied.
This sounds like a very good point! Can more people comment on this? James?
I agree, it's not the issue its said to be. I also was certified in the 90s. Funny that in every other industry the 1/4 turn is standard.
i totaly agree on this , 20 yrs expieriance as navy technician , the quareter turn back is the ONLY safe way
Someone said it before, all other industries using pressurised gas tanks use a quarter turn. For good reason. Since most divers do not own their own tanks, and dive centers use their tanks til they don't pass hydrostatic testing, anymore. You probably will dive with tanks that may be 20 years old. The servicing of tank valves with the current low pricing in the industry is not done on a yearly basis. It is done when the valve actually does not work anymore. These are just the simple facts of reality. So quarter turn is still a must.
The inherent point here is training, and proper check prior to a dive. (No shortcuts)
Agreed, I'll be sticking to the quarter turn
If i buy a 3442 psi steel scuba tank with pro valve fitting and i screw out the din screw to make a din fitting will the tank din thread be 5 or 7 threads deep.now if i buy a din fill station in the uk will it fit regardless if the male din adapter on this fill station is 5 or 7 threads deep thanks
Hey love the vids. Any idea of when your review of the Hollis wings will be up??
An other version of the "Wide open, and then closing 1/4 turn" - The idea is that if a buddy is out of air and the buddy is hanging on your octo - then it is very fast and easey to feel (with 3 fingers, for both divers) if the valve is loose (open). If it is loose then abort the dive at once, together. You might be out of air soon, too!
WHAT..........................
Nope.
I’ve messed up a few times where I only opened the valve a 1/4 turn. I didn’t find out till after my 140’ dive was complete. Also, I back the knob off just a smidge from all the way open. There’s been too many times where it’s all the way open and I couldn’t close it during a valve drill and had to have my buddy bust it loose. 1/4 turn is too much.
What I do is, I open the valve fully and then loosen it, so it screws easily in case I need to close it. You don't want to be wrenching your valve if it's opened all the way and then some when you get a freeflow.
Hi James, Great Video series.
I just purchased a new Catalina 80 Alu tank where I want to replicate my old US Diver 80 Alu from the 70's with new decals. Should be a conversation piece.
Here's my question: The original USD J-valve is cosmetically in great shape and still on the old tank with 200~300 psi still in it and has not been used in 30 years.
Can its J-Valve be serviced and used on the new tank?
The valve should be cleaned and get a new o-ring before installation. Otherwise I don't see a problem.
Would all this (and more, I assume) be taught in an equipment class? This sort of stuff appeals to my nerdiness and I’d love to learn more.
Thanks to upgrade my qurter turn knoledge !!!!
Thanks for the video. Good explanation, however I disagree with the conclusion of totally open.
Is that you Henri?
Why? Please provide an explanation.
@@ppo2424 yes, who is this?
@@nicwelch simple really, the entire gas using world is using the quarter turn back, so why should we change an international industry standard on the usage of gas tanks. Then furthermore, totally open works in a perfect world where all tank valves are new, but they aren't. I think the debate on tank valves should not exist in the first place, we have a set standard, it has worked out well so far.
@@oceanroamers To be fair, that's just not good enough. First of all the entire gas using world does not do this, at least not in welding. Full open or nothing, that's standard where I live anyway. Second, just because it's always been done a certain way does not mean there isn't a better way. I do understand thermal expansion being a problem when you go to shut the valve and it now being too tight but unless you're cranking on it with your hand it should be fine fully open right?
James, when a valve when connected to a regulator, leaks on the handle, what is the problem?
The packing nut is loose, or the teflon packing itself is compromised. Either way, the valve needs service.
@@Andrew-ps6xe Thanks.
I’ve seen lots of videos on scuba wetsuits and what’s needed for colder waters. That said. Can you be too hot on a scuba dive?
Yes you can. In the Florida winters I wear a 5mm, in the summer just a rash guard.
Sadly, during my last liveaboard, I've had to do the quarter-turn - otherwise after the dive the valve would only close with a wrench. Seems like that tank was in dire need of service.
The reality of using rentals, hence the 1/4 turn.
Did you check if there was a service date on the tank?
@@ppo2424 Fair point. I just trusted the operator...
Was it the old style pillar valve? If so that design is exactly why the quarter turn used to be done. They would not close after using the tank, and the only option was a wrench or blowing an o-ring.
The one thing I found that you have to watch out for is a dive guide who checks your valve as you are getting ready to do a giant stride off the boat. I have seen some actually test the valve then do the quarter turn back. So just be aware of that so you can tell the dive guide to not do that for you.
Why would you? because of the word of this bloke? Do your homework.The quarter turn is valid
@S M Talking of attitude...
@S M How many dives do you have under your belt.? Dm's check beginners tanks,because if they didn't a lot of people would be submerging with their tanks not fully open.That said I only think it is necesarry during training.
@S M I've also seen it done like that and no I don't agree with it. As an instructor I have to be self sufficient, and one check i always do is the spg while taking a breath
@S M Yep, I've done around 3000 dives, I worked in the industry for 12 years and might dip my toe back in at some stage.Dived with a few military divers,they were obviously very good.
Nice video, it would have been better by comparing the old design with the new one. A question would be how to you know if a cylinder is the old design or the new design, in particular when you are in remote locations where they have very old stuff. Would you leave the valve open all the way in the old design as well? On another topic, is that a Teric? what happened to the Garmin?
The old valves are really old by now and I don't think any would be in use by a commercial dive operation. I think it was back in the 1970's when the upgrade took place. Hence, the 1/4 turn has not been needed for longer than most divers have been alive. I'm pretty sure Alec Peirce's UA-cam channel talks about this in one of his tank valve videos. IF a commercial dive operation was still using valves so old they needed the 1/4 turn, I would not walk but run away.
@@jeffworst9939 Thanks for the clarification. I was naïve by thinking that the training agencies would have updated their protocols in 50 years... haha. We just need to re-train ourselves. I hope I'll remember this next time I go diving... what was the thing about old dogs and new tricks...
@@luisj8970 It's been a while since I took OW, ... is the 1/4 turn still in an agency training manual?
thanks
Does a quarter turn back from "full open" actually hurt anything? For all of us who learned that particular rule decades ago, I've always done it. Never created an issue with my gas supply. And after viewing thousands of videos, blogs, etc., you're the first person I've ever heard saying don't do it. My "forever buddy" (wife) quit diving years ago, so I'd say 80% of my dives over the past 15 years have been with a DM. None of them, during the pre-check, have ever said anything about that.
Shower knob valves are nowhere near as complicated as dive tank valves - but one of the reasons a valve stem on a faucet begin to fail is because people (my wife, LOL) cranks on that knob as hard as she can when turning the water off. The valve stem washer gets worn out.
So I guess I just don't get the harm in a quarter turn back from fully open, especially considering it took 2-3 full turns to get to full open to begin with.
Never touch another divers gear unless it's your dive buddy and you have been asked. As a dive master I did a lot of work on Southern California Liveaboards. I promoted the take a breath while watching your regulator. I started doing that back in 1988. Always put people in the position of self reliance. Don't touch other divers gear even if you are an instructor or dive master or boat operator.
Australian standards for gas cyclinders requires a half turn back to avoid seizure in an open position. Sighted from BOC standards Australia- Guidelines for gas cyclinder safety.
When I take a new diver to Peacock I like to tell them how this is where Sheck found himself out of air due to the quarter turn, while being upside down and stuck in the crack.
Good one and I have seen many issues with valve operation in the past. Valves only opened a bit that didn't deliver at depth, "friends" thinking they are being helpful by touching your valve. I can see from the comment below that there may be some confusion about "1/4 turn". You spoke about having the valve only 1/4 turn open, but there is also the practice of "opening the valve wide open, and then closing 1/4 turn". There is some logic to this and it is the way I have done it with all HP gas cylinders. If you open it wide and turn it back 1/4, you will always know what position it is in when you check it later by giving it a quick test. If you open it 100% and maybe a bit too tight, then there is a chance that when you try it, you will torque it open even more and stress the seats etc. Having said that; there are a lot of experts that say open the valve all the way.
Hi Barry, I'm going to respectfully disagree with you on this one and side with James... Open or closed----nothing in between. The issue is when you think you've opened it 100% and then 1/4 turn back when actually you closed it 100% and done the 1/4 turn back. Now it's open just a fraction. I have filled 10's of thousands of tanks over the years, but, being human, can still have a brain fart. I don't think that anyone has perished from having a tank jammed open. Have a very pleasant evening.
I always turn my valves all the way open and half turn back. The reason for this is that I had so many stupid divers not know how to shut off thier tanks and rip the valvle threads. Its safe, turning half a circle wont prevent air flow.
Tip#1 turn the air on before you jump in.
The rest you can deal with at depth.
That comes with training
Damn, I'm old. haha. Still do the 1/4 turn. Maybe I'll stop this year.
Had a rental tank I couldn’t shut off because the square drive was gutted. It had just enough left in it to open the tank. Everybody looked at me like I was a moron venting out the entire tank on the dock to switch it out. One guy said just dive it… pass.
Another good video. The background music not so much. The music is distracting and diminishes the content. Sorry James.
July 2024: to your point.... just had a 77 YO diver die while shallow in a quarry dive in KY and it was found that his tank valve was only opened 1/4 turn. It is suspected that he confused "righty-tighty / lefty-loosy" and instead of opening his valve some time after his equipment was set up, he shut it and cracked it open 1/4 turn.
FULLY opening the valve is the ONLY way.
Tragic....
Interesting. In Europe we don't use burst disks.
Loving your channel. But this time, erm. No. You open your cylinder all the way, and then 1/4 turn it back. No mechanical reason. Simply: if the knob turns (three fingers, no effort) a bit in both directions it's open, if it doesn't turn at all it's closed. Then again, never underestimate the power of the "silly people"... ;)
Insert, slug, converter, nugget, sometimes also pre-fixed with "DIN". Now I have two more names for the 'A-clamp to DIN thing', doughnut and DIN nut 😉
Don't forget International for A clamp
One more for you- INTsert
Taught 1/4 back in 1980s. The rationale that valve can get stuck open made sense. So applied the principle to all valves - water taps, gas cocks, etc. Never had a problem with valves I’ve opened but have come across many stuck open valves due to temp change contraction/corrosion from not being moved over a long period of time. However, was recently advised to only open LPG gas valves 3/4 of a turn at most. Sufficient to open the valve for LPG gas to flow but able to be closed with one twist of the wrist in an emergency.
So it seems, full open for scuba valves, 1/4 back for water taps & only 3/4 of a turn open for LPG gas.
My Instructor(PADI) said to Never Turn Back 1/4 Turn. So that we know the Valve is Open.
Wish they would have named the DIN adapter a "DINnut. I remember when the 1/4 back was gospel - never liked it for the 1/4 turn open reason. 3 thumbs up from the mutant divers!
we call them "INTsert" here
(because our association dives DIN most of the time, so it's the optional insert to make it INT)
Pretty sure they are Teflon washers not neoprene
They are.
Something to add. I do not see many people, especially with rental gear, ensuring they can reach and operate their tank valves while diving. Not needing someone's assistance to open and close the valve can be extremely important. If everyone could reach their valves and know which way is open and closed, this point about the 1/4 turn becomes less relevant.
Finger tip turns, no returns, no backing off.
Divers Ready only having 50k subs in all honesty proves how horrible youtubes algorithm actually is.
You said a bunch of people died because they only turned their cylinder on a quarter of a turn. fair a statement. However that has nothing to do with fully on and back quarter of a turn. By the way I was trained half a turn. Typically a dive cylinder valve takes around 5 to 8 full turns to turn on and off. 1/2 a turn back is not gonna cause I shut down. Have a look at the construction of the valve. I cannot see how that High pressure Teflon seat can have a shut down because of a half turn. It physically cannot happen unless the valve spindle is turned. You are wrong about an incidental shut down resulting from a half term. I would be happy if you explained how the Teflon seat could do another 5 1/2 to 7 1/2 turns to shut down without the spindle been turned by other means.
Neoprene washers? I think you mean nylon...
Burst disks should be built into fill whips rather than scuba cylinders. Why should I die in a cave because my burst discs have corroded to prevent an accident in a fill station? It's a flawed design that makes no sense.
I'm paranoid AF,
stories about people being sabotaged
someone turn my valve off
I was just taught this
turn 1/4 back, wtf
You were taught correctly
@@ppo2424 You really need to back your statement using logic reason and evidence, as this gentlemen did. I don't care how many dives you have under your belt either.
??????? ?
SUBOPTIMAL 🤣🤣🤣