How To Open The Tank Valve

[Sifossifoco]

Just open gently. And if you are opening an oxygen cylinder, open VERY gently.

 

[boulderjohn]

When I first became a DM assisting classes and later an instructor, this was standard instruction in our dive shop. I later learned that it was not necessary, and so I became the first maverick to tell students to open their valves slowly until the hoses pressurize and then go full speed.

 

[boulderjohn]

Just in general, in my years moving from DM to instructor and beyond, I realized that a whole lot of stuff being taught in OW classes begins with someone having a bright (but not necessarily correct) idea, making it part of instruction for all his or her followers, and having that idea spread out as those followers teach it to others. There are countless things being taught in scattered shops around the world that are not taught anywhere else.

Other sources for erroneous "rules," as was explained to me by a PADI official, are the many dive instructor schools around the world that promise their graduates that they will get top scores on the instructor exams. PADI (and most agencies) do not specify precise steps for most skills. Because these schools want their students to get top scores, and because they cannot know ahead of time what quirk an instructor examiner might have, they often put every possible step into what they teach their students. If there was ever an instructor examiner anywhere in the world who liked to teach a particular step, that step was going to be in the process they taught everyone. The PADI official told me that if you were to get a group of their students together and signal them all to do a skill at the same time, it would look like an elaborate synchronized swimming routine. I had this conversation with PADI after a recent graduate of one of those schools insisted that the processes of putting gear together and doing buddy checks that he had learned were all absolutely required steps. Those processes had so many unnecessary steps that it was a wonder anyone could do them all and still have time to dive. Yes, he insisted we had to push the purge valve down while turning on the valves.

What then happens all too often is that people who learn one of those scattered ideas in their shop assume that what they learned in their OW class was the way it was taught in ALL OW classes at the time. They then get on ScubaBoard and decry the way standards have fallen when they hear that agencies are not teaching that anymore.

 

[ThatDogDontHunt]

My approach is to open the valve relatively slowly (to pressurize things gently) while NOT looking directly at the SPG (in case the SPG should blow out). Usually I will hold the SPG with its face against the tank as I slowly open the valve. This is what I was taught in my open water course in 1986, and I continue to use this approach.

ETA: My course used Scubapro and U.S. Divers regs. It's possible to open too slowly for some regs (e.g., Poseidon Odins).

rx7diver

Does your SPG have a blow out plug? Is that plug on the back of the SPG?

 

[rx7diver]

Does your SPG have a blow out plug? Is that plug on the back of the SPG?

"Yes" to both questions for my Scubapro SPG's. I'm not sure about the U.S. Divers SPG attached to my DA Aqua Master, since it is in a boot that I have never removed.

Holding the SPG such that its face is against the tank is to prevent you and anyone else from getting a face full of shards of glass or acrylic or shrapnel from the brass Bourdon tube, etc., in the case that the gauge blows out through its face as it's being pressurized initially. I suppose that if the blow-out plug flies out, then either the SPG boot or the palm of your hand, gloved or not, will receive the punishment.

rx7diver

 

[TMHeimer]

I was taught this in the Rescue course by an instructor who now is a PADI Course Director. It made sense to me and I always do it. I think his reasoning is it gives the pressure somewhere else to go besides to the glass in your console (who uses a console now?). Someone a few years ago on Scubaboard explained reasoning why it does nothing one way or the other. Can't remember the reasoning.

 

[divezonescuba]

The only time I have ever seen this was during a Mares regulator technician course taught by the head Mares engineer.

IIRC it had to do with the sudden pressure differential in both regulators possibly causing premature wear on the seats.

I don’t practice it, for among other reasons, it scares people and attracts attention. I have not noticed any unusually wear of either the first or second stage seats.

I would add though, that I did have a first stage seat fail to function once on pressurization and it damaged the second stage seat as it received 3000 psi when it is only designed for 145 or so.

 

[boulderjohn]

I was taught this in the Rescue course by an instructor who now is a PADI Course Director.

And I was taught it by a PADI Course Director who had been himself taught it by a PADI Course Director, but it is nowhere taught officially by PADI.

That same PADI Course Director was the first person I DM'd for, and he came up with a bright idea of his own. When teaching students how to help each other gear up while standing beside the pool, which he scheduled right before the giant stride entry, he realized that if they put their fins on in the correct order (with the figure 4 technique holding onto the buddy's shoulder), they would end up facing the pool, ready for the giant stride. Before long, it became a required step in the process, and people not doing it were not doing the skill correctly. Since he was the director of instruction for the shop, before long all instructors were requiring students to put their fins on in that order. When I became an instructor, I realized it was stupid, because divers gearing up that way are not likely to be on the side of a pool preparing to do a giant stride, and they had to face each other for a buddy check anyway.

Decades ago agencies wanted to teach students that inhaling made them more buoyant and exhaling made them less buoyant. They wondered how best to do that, and the fin pivot was born. That was its only purpose, because it is not something you ever actually do on a dive. Well, instructors all over the world made it an art form, with elaborate rules (knees locked, fin tips on the floor at ALL times, never touch the floor, arms folded, etc.). What was supposed to be a simple little learning exercise became the hardest skill in the OW class. That is why PADI eliminated it years ago--it had become the Frankenstein's monster of scuba instruction.

I am sure many people can tell you stories of things that are taught in scuba classes that are not true and have never been a part of official agency instruction--the most famous being, of course, "if you put your mask on your forehead, a DM will assume you are panicking and will leap in to assist you."

 

[CycleCat]

When teaching students how to help each other gear up while standing beside the pool, which he scheduled right before the giant stride entry, he realized that if they put their fins on in the correct order (with the figure 4 technique holding onto the buddy's shoulder), they would end up facing the pool, ready for the giant stride.

My SSI instructor earlier this year (who also taught me to purge while pressurizing) taught us the fin technique you are talking about. Buddies start facing away from the pool and take turns putting on their outside leg fin. Then rotate toward the pool and each put on the last fin. Then you are facing the pool ready to giant stride in.

 

[Raphus]

Decades ago agencies wanted to teach students that inhaling made them more buoyant and exhaling made them less buoyant. They wondered how best to do that, and the fin pivot was born. That was its only purpose, because it is not something you ever actually do on a dive. Well, instructors all over the world made it an art form, with elaborate rules (knees locked, fin tips on the floor at ALL times, never touch the floor, arms folded, etc.). What was supposed to be a simple little learning exercise became the hardest skill in the OW class. That is why PADI eliminated it years ago--it had become the Frankenstein's monster of scuba instruction."

Padi is not teaching fin pivot anymore?



I learned( also from a CD) that it will increase the lifetime of first stages.
Because when turning the pressure on and it has no place to go. The air will hit the first stage and create heat in that point.
This heat is less, when some air can escape through a 2. Stage.

I am sure its not necessary, but its not harmful aswell. And for me it sounds plausible.