Question for Instructors

[rstofer]

There are older valves that have the seat on the end of the valve stem and it seats on the bonnet. These valves require the valve be fully opened.

Newer valves have the stem run through a seal and these don't have to be turned fully open.

My personal opinion: open it fully and JAM it! Then don't let ANYONE touch your valve. Not your buddy, not the DM, not a passerby, NOBODY!

Then breathe from your regulator and watch the pressure gauge.

FWIW, I always open the valve very slowly.

Richard

 

[friscuba]

Talk to an engineer.

I've had several tell me it's standard to open valves all the way then close it 1 quarter turn. I think most of it has to do with what Halemano mentioned earlier.

I've seen people stick their tank valves fully open a few times over the years... it's a pain in the arse, gotta blow the tank empty.

 

[friscuba]

With regards to DM's and Captains turning divers air all the way off as they left the boat; If the 1/4 turn back off was enforced at least it would be 1/4 turn on.

I tend to take that thing about DM's and Captains turning divers air all the way off with a grain of salt, at least with any DM or Captain that works on a regular basis. I saw a post in those regards a year back or so, and it just so happened the poster mentioned a company and Captain by name. The poster said he had turned on his air and the Captain turned it off prior to the second dive.... I worked with that particular Captain for 4 years before getting my boat and I know his routine... he's had the same on/off routine since '91 and has worked on dive boats 5 days a week since then... his wrist only goes one direction before a dive, he turns on all tanks about 3-5 minutes before the second dive.. I suspect the poster followed the Captain and turned off his own air.

 

[ZenDiver.3D]

I teach open all the way and a quarter of a turn back because I have seen them stick on an occasion. That has nothing to do with people turning your air off.
I don't care who screws with my gear, before I enter the water, I check it myself. I teach my students to do the same. Your gear, your responsibility. Plus, there are enough fools who will turn off your air for whatever reason, that I double check my stuff every time. It only takes a second.

 

[TMHeimer]

I must admit that maybe twice over my 4 yrs. diving a forgot to turn on the air (shore dives). I'm not sure what DMs and Captains are doing turning tanks on. Yes, it's the diver's responsibility. I've had crew ask if everyone's air is turned on. Maybe the reason they check tanks themselves is to prevent divers jumping off the boat without air on and they want to head off the problem. Maybe a better way to check would to inspect every diver's SPG?

 

[miketrance84]

I have had a DM turn of my air at a resort in Honduras. He was a very skilled DM and just made a mistake.

I guess the moral of the story is always check your own gear before entering the water. I did the check and found that the tank was off. No big deal to have him turn it back on. Like several posters have said look at your SPG while breathing from your regulator.

Everyone makes mistakes even the captain that has done it a million times. Absent-mindedness effects us all. :: On a side note:: I like having my BC partially inflated before entering the water from a boat. Lets the boat know everything is ok before I decend. Also serves as a secondary air check.

 

[QatarDiver]

I think I'm going to say 'pony bottle', why ever have a single point of failure, even if that failure is the result of a DM/boat hand/insta-buddie doing something daft?

I agree with other posters, the single most important check is to take 2 breaths while watching the pressure gauge, if the pressure drops, STOP!

 

[knotical]

http://www.scubaboard.com/forums/ba...172-why-turn-cylinder-knob-back-1-4-turn.html

http://www.scubaboard.com/forums/basic-scuba-discussions/91704-half-turn-close-tank-why.html

http://www.scubaboard.com/forums/tanks-valves-bands/114155-quarter-turn-back.html

and from the tech forum:
http://www.scubaboard.com/forums/technical-diving-specialties/230420-valves-full-open-not.html

 

[Web Monkey]

I have a question about the current instructional practice of opening tank valves.

Back in the day, divers were told to open their tank valves all the way and then back off 1/4 turn. The reasoning was so someone could determine an open valve from a closed one.

You should be able to reach your valve, so you can check it and open it if necessary at any point before or during the dive.

Regardless of what anybody teaches or what you thought you did or what the DM thought he did, there's always the chance that your tank is not fully on. Being able to just reach back and crank your own knob can be the difference between annoyance and panic or death.

Terry

 

[MauiScubaSteve]

I'm not sure what DMs and Captains are doing turning tanks on.

On many dive boats the owner of the boat mandates that the crew turn the tanks on before the dive. The boats I have worked on in Hawaii all have that operating procedure for the crew.

When guests arrive at the boat WE set the gear up on a tank, then WE open the valve to check tank fill and gear operation (leaks, etc). Then WE turn the valve off and purged the lines; WE don't want guests purging off some air during transit.

Before the dive the crew verifies that every divers tank is on, which usually means WE turn every tank on. Since many vacation divers do not notice what the crew is doing and often can't remember lefty loosy, righty tighty, it is also typical for crew to check the valve again as the diver approaches the water entry position. The owner of the boat requires that his crew do these things; it's part of the job description.