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Post by vance on Oct 27, 2016 9:21:49 GMT -8
I don't think I could crank open a valve and not back it off. As Red pointed out, it's muscle memory! And, if I forced myself to do it, I bet I'd be thinking about it obsessively until I went back and "fixed" it. Old dog/no new tricks......
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Post by red on Oct 27, 2016 12:10:18 GMT -8
Sometimes, leaving on a trip or something, someone will ask me "Did you lock the door?" and my answer is often "I don't know, I must have." Simply because, again, it is muscle memory. I was a city kid, and city kids are ALWAYS taught that you lock a door when you enter or exit. You don't get your keys, and you don't get to come and go by yourself, until you've got that drilled into you.
Same way that I get into the car, hit the starter, buckle my seat belt (which gives the engine time to build oil pressure) and then take off. Well, except the old car had a hand brake and the new one won't LET me release the parking brake until the engine has come up, so I have to reprogram the sequence in the muscle memory on that. Or, go back to a vintage car.(G)
I can scarcely wait for PADI to redesign the tank valve: Take a selfie with the built in webcam, which will validate your certification with PADI central, then cross-check your dive schedule or booking, compare it against Google Bathymetrics to make sure you're not diving too deep, and then the tank valve will automatically open and the wireless air-integrated computer will start performing a sequence of self-tests.
Heck, all the EVA suits on the mothership do the same thing. Been doing it that way for years now.(VBG)
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Post by thetrueseahunter on Jan 8, 2017 9:45:17 GMT -8
This is an old thread but NOT an old topic. In a recent 'Tech Tips with Alec Peirce' on U-Tube I addressed "The Things Your Scuba Instructor told you that are Wrong!" Among them was the 1/4 turn back. Please alow me to share this. The 1/4 turn back was to prevent the old pillar valves from "freezing" open. At that time there was no discussion about whether it was to guide the diver about the right way to open the a valve or for safety.
Of course the valve didn't really freeze but the dissimilar metals they used would bind as they cooled under pressure. The solution was to ensure the valve was not turned fully open. For the record, there is no 'balanced' valve. Balancing implies equal high pressure on both sides of the valve which is simply a non-starter for high pressure tank valves. They have become easier to open and close but that's a function of the materials more than anything else. Some design changes have helped too. Larger orifices, silicon seats, silicon back-up rings, etc, have all helped. And, the other benefit of the newer materials is that the valves no longer freeze or jam open. Hence, the 1/4 turn back has no basis.
Now you can argue all day long about whether or not the 1/4 turn back is good or bad from a safety point of view and each diver can decide on his own what he wants to do. But, my point is, the practical reason for the 1/4 turn back simply does not exist anymore.
Having gone this far, I might as well jump into the fire. In the U-Tube video mentioned above I make the point that what was right in the 60's and 70's may not be right today. To blindly follow what your instructor told you or what is written in scuba texts that are all 25+ years old leads me to believe that you also don't like nor use cell phones. The wall phone works perfectly well and can't be tracked!! Many of the posts freely admit that they don't understand the basis for the 1/4 turn back. All the more reason to find out and reconsider rather than blindly follow a faulty practice. "That's what my instructor said" or " I've been doing it that way for 20 years" or "That's what is says in my New Science ... textbook from 1975" are NOT good reasons.
Aside from the fact that the 1/4 turn is no longer needed from a technical view, I think it should not be followed for several reasons. 1. with a 1/4 turn back the orifice is smaller which restricts the airflow a little bit. Probably not a big deal but there it is. 2. If the valve is neither open or closed, that is, in between, a diver and or his buddy or the divemaster when checking the valve may decide to turn it completely open .. or is that closed? 3. New divers can be easily confused with a bunch of useless "tips". Is that a 1/4 turn or a full turn? How do you measure a 1/4 turn? Maybe it's a 1/4 turn open! Open or closed is hard to confuse.
I'm sure some will object to parts or all of the above but before you chew my head off, I did not say "You're wrong". I DID say "Here's the reason - do what you think is best." And before you try to pull rank on me and say you've been diving a long time, I started diving in 1958 and have been servicing gear and training divers since 1969.
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Post by cnotthoff on Jan 9, 2017 10:25:15 GMT -8
I must be an agreeable guy, because I agree with each comment. There's really no compelling reason to turn the knob back. I've done it for so long, I have to force myself not to do it. I no longer include this technique for scuba students.
One good thing about the 1/4 turn is that it has divers thinking about treating that valve gently. If trueseahunter is still servicing scuba cylinders, he has seen the damage that paintball enthusiasts who have never been taught how to handle a high pressure cylinder valve can do. I see valve seats with the nylon damaged so nothing is left but brass against brass. I've even seen the seat stem broken by some gorilla reefing that sucker shut.
My current advice is to use only a thumb and forefinger to operate the valve. If it takes more than that, the valve should be serviced.
Good Dives,
Charlie
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Post by Seahuntjerry on Jan 11, 2017 18:51:13 GMT -8
Hi, I believe I'm one of those guys who started this thread . Yes now after of many years of diving as Alec Peirce has we open the valve fully. Checks Dan's official publication on 13 Ways to run out of Air &How not to
7.Not opening the valve all the way.Plus more safety info in their publication
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Post by tomcatpc on Jan 11, 2017 20:35:59 GMT -8
I am probably one of the newer Divers here (2014). I was taught to turn the valve open all the way, and then back off 1/4 turn. Whilst I was going through my Open Water Course, I started to hear about people debating this issue (in online and Facebook pages). My Wife took her Open Water class last Spring and I went to the classes with her. If I recall, her class was taught to open it all the way and leave it open. Mark
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Post by red on Jan 12, 2017 10:09:14 GMT -8
Alec makes good points about the "quarter turn back" rule being less than optimal for the scuba valve industry. I totally understand what he is saying and why it is being said. And that's where tunnel vision and 'driver distraction' from complications and conscious thought get in the way of generally superior "instinct" and muscle memory.
Do we want "Another damned rule for another piece of specialized equipment, let me stop and think about which rule applies here" ?
Or should we be able to fall back and rely on one simple "Rule for rotary valves" which we apple to ALL rotary valves, all the time, so there's no potential error of confusion?
There was a relatively famous automobile insurance suit brought maybe 20 years ago, involving an accident where the driver failed to use their horn, and the driver's defense was that it was a rental car and they TRIED to use the horn, but the auto maker had put it on the headlight stalk, not the steering wheel "Where god and Henry Ford long ago decided it ought to be". And that the automaker was liable for changing a long-standing standard, effectively hiding the mandatory horn function.
Some things are done in a standard way, not because it is the best way, but because it is the expected standard, and can be relied on to be the same way, every time.
Next I suppose we will see boat operators who not only log your tank pressure pre and post dive, but log the tank valve position as well?
DAN safety experts note that while compiling "cause of death" statistics for divers, they are still seeing very high numbers of simply "out of air" incidents. Despite wonderful new gauges and air-integrated systems, divers are simply not paying attention to simple self-reliance i.e. checking their air remaining. And they are dying because of this. The Nanny State is a wonderful concept, but not for diving. If a diver can't deal with some things, they shouldn't be diving. Except perhaps with a tandem rig, lie sky divers.
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Post by vance on Jan 13, 2017 10:06:26 GMT -8
Red, what you are doing is highly recommended by safety professionals and industrial hygienists. I worked for many years in these fields, and the discipline is called "ergonomics." Displays and controls are a part of this, and these visual indicators and one of the best controls for our problems of slightly open valves. Here is where, on Amazon, these "Vindicators" can be purchased. www.amazon.com/Vindicator-Visual-Indicator-Scuba-Cylinder/dp/B00COC4C6AYou can probably get a slotted screwdriver from Herman too, making the changeout very easy. John You know those prongy weed pullers that look like a screwdriver with a bend at the end and a V shaped notch cut in the flattened part? I pounded one straight and filed out the notch to fit over the stud. Fits perfectly...
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Post by red on Jan 13, 2017 11:42:14 GMT -8
Searat- I think it comes from having been cold and wet and tired and having to get things right the first time anyhow. I'm not sure that "doing it by rote" is quite the same as ergonomics, but I do recall the aftermath of Three Mile Island with all the rows of uniform neat controls, where one of the changes to the nuclear industry was the recommendation to use beer taps for handles. People can learn to "pull Budweiser" much faster than they can intellectualize "third lever, left bank". I've already joined the choir and endorsed the (horribly misnamed) vindicators here. Do I need them? No, but they help me ensure I'm not doing something stupid. I'm happier when the sea gods say "Oh, he's no fun to play with, let's go mess with some one else."(G)
Vance- Any shadetree mechanic will tell you, a pair of needle or chain-nose pliers can span that screw, so no slotted screwdriver is needed. But there are what are probably not called "compass pliers" that can be adjusted to span things like that, similar to watch case back tools. For one-time use? Yeah, I grabbed the skinny pliers. Then I had to do it twice more anyhow, because you may need to fiddle with the vindicator sleeve to make it indicate most clearly, according to your valve size. (Who reads instructions?)
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Post by nikeajax on Jan 13, 2017 11:58:59 GMT -8
You know those prongy weed pullers that look like a screwdriver with a bend at the end and a V shaped notch cut in the flattened part? I pounded one straight and filed out the notch to fit over the stud. Fits perfectly... I made my own tool for removing the "spring-holder-downer" for my Dacor Olympics out of some steel strapping after I took down part of the ramada in my yard: I love home made tools! JB
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Post by vance on Jan 13, 2017 17:56:37 GMT -8
But mine can still pull weeds....
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Post by nikeajax on Jan 13, 2017 18:06:33 GMT -8
Yeah w'll, I can throw mine at stray dogs!
JB
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Post by chrisdee on Apr 10, 2023 13:08:17 GMT -8
John- Part of the "1/4" philosophy is probably a tradition from gate valves, which has no purpose with these. Gate valves in particular tend to corrode and fail, physically getting stuck. But any rotary valve has a "human interface" failure mode, where someone is hot, or cold, or tired, or seasick, and they crank the valve the wrong way. Now, if the valve was already all the way open and they crank the wrong way, they're really going to jam it, and now it is stuck open until you find a bigger gorilla. But if you back the valve off 1/4 turn, then it doesn't matter. They get to turn it 1/4 turn and it stops--which usually gives them the message "D'oh! Turn it the other way!" and there's no damage done. At least, that's how we were taught the 1/4 rule was supposed to prevent problems. Washers? O-rings? Valve seats? That's what maintenance is for.(G) Not just gate valves. There are a whole host of valves where the "material" can get lodged against the stem and under the final cap / nut/ etc, especially some OS&Y type valves. When this happens the stem is failure prone due to whatever reaction happens. This is such a common issue that most all industry have procedure where they exercise the valves by closing them down a bit and then reopening them. As part of a preventive maintenance schedule. This flushes out the stagnant "material." Those toilet and other bathroom stops are particularly prone to this kind of water corrosion. Many valves in industry are never fully open because of this. Being partially open flush's the stem, AND THE VALVE LASTS LONGER!
If you want the valves in your basement to last longer, this is a great idea!
Now, I just was in my NOAA stuff, 2023, various manuals,...AND LOW AND BEHOLD THERE IT IS IN THE MEDICAL SECTION UNDER STANDBY OXYGEN!!! In full color pictures. "How to turn on a o2 tank." In full detail, "turn valve fully open, turn back 1/4." Ther yo have it, from NOAA of all places.
I'm going to git those new red valve sleeves for my Din tanks. (when valve is off, red sticks out, open fully the red disappears) (10 bucks for a piece of plastic that fits under the scuba tank knob.) Thanks RED.
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Post by vance on Apr 10, 2023 14:32:54 GMT -8
Hi chrisdee (I assume, Chris),
Welcome to the board. I see you just joined. Please stop by the welcome center and introduce yourself. We're a friendly (OK, nosy) bunch and want to see and read about your vintage stuff!
Also, please check out how to post photos in the tech section. This board ran out of free space long ago, and we all use photo hosting sites such as Imgur and Flickr.
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Post by SeaRat on Apr 10, 2023 15:48:27 GMT -8
Chrisdee,
Welcome to our forum, and thank you for this information on the valves and the 1/4 turn back. I was taught that in the U.S. Navy School for Underwater Swimmers in 1967.
Your entry about the NOAA information on the 1l4 turn led me to look at my NOAA Diving Manual for Science and Technology, 1975. And, there it was in this manual:
I still use the 1/4 turn on my own valves, as that's what I've been doing for over 50 years.
The reason we are now being instructed not to do this is that on these hired dive boats, there have been instances where an open valve was closed by the divemaster and the backed off 1/4 turn. The diver on the surface still gets air on a check of his system, but once going down say 33 feet (10 meters) the regulator no longer puts out enough air for the diver, and there have been emergencies concerning this. I don' do dive travel, and so this is not a problem for me.
By the way, do check in to our "Welcome Center."
John
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