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View Full Version : How open do you keep your iso valve?
MASS-Diver April 14th, 2003, 02:50 PM I just finished reading "Fatal Depth," in which the author reports that many people dive with their isolation valve just barely open so that if they have to isolate a tanks they only need to turn the valve a small ammount. Do you dive like this? Is it easy to roll a isolation valve shut? What's the DIR position? WYDT April 14th, 2003, 02:55 PM MASS-Diver once bubbled... I just finished reading "Fatal Depth," in which the author reports that many people dive with their isolation valve just barely open so that if they have to isolate a tanks they only need to turn the valve a small ammount. Do you dive like this? Is it easy to roll a isolation valve shut? What's the DIR position? Wide F**kin Open - hey to DL! ;) The only way you will need to actually isolate your tanks is if you loose a burst disk, tank neck o-ring or the isolator itself starts leaking on one side otherwise you just shut off the post that is giving the problem. A situation that would require isolation is very rare and shutting down is very quick and easy if practiced. Leaving the isolator "barely open" is inviting a real problem to occur. Another "fix" for a non-existant problem. WreckWriter April 14th, 2003, 02:56 PM Rob is exactly right. Wide open. WW Wendy April 14th, 2003, 03:01 PM ditto what the guys said....wide open...especially when filling your tanks. Capt Jim Wyatt April 14th, 2003, 03:28 PM I have always kept it about half way or less open so a shut down can be done more quickly. Clearly leaving it barely open could be a problem, but half-way does not seem to me to be a problem. What trouble is one inviting if the valve is not left wide open? O-ring April 14th, 2003, 03:34 PM Only closed if in the middle of a valve drill.. :D MASS-Diver April 14th, 2003, 03:50 PM I see, that makes sense. So, if (for example) your primary reg starts free flowing - you reach for the post and shut it down there (so as to save the air in it), you don't go for the isolation valve first (or even second). So, really being able to reach and shut down each post is just as important to practice (as part of a valve drill) as is working one's isolation valve. Along the same lines, an even more basic question: how much do you guys open up your tank valves (does how fast you can close them play a role?)? Capt Jim Wyatt April 14th, 2003, 03:58 PM The tank valves must be wide open to prevent a restricted orifice at depth. MASS-Diver April 14th, 2003, 04:02 PM It's OK to crack them back a little bit though right (1/4 of a turn)? Capt Jim Wyatt April 14th, 2003, 04:11 PM I have always closed mine about 1/4 turn back. The reason I do that is so if the valve is bumped it won't jam it in the open position. Wendy April 14th, 2003, 04:16 PM Is the 1/4 turn back even taught in classes anymore? I had heard it wasn't. Oh and I keep my valves wide open as well. Capt Jim Wyatt April 14th, 2003, 04:49 PM but I am not sure if its in the "official" PADI cirriculum or not. I have never heard of a valve getting stuck open due to this...but its just something I have always done. It may just be superstitious behavior MikeFerrara April 14th, 2003, 05:05 PM Current recommendation in the PADI text is all the way open. Too many people turn it off then 1/4 on instead of on and 1/4 off. Then divers have trouble at 50 ft lol. If it's turned all the way off instrad of all the way on tou'll know it soon. I use all the way on or all the way off and no inbetween with all scuba valves. Capt Jim Wyatt April 14th, 2003, 05:17 PM that people do not know how to open a valve/close a valve. I see certified divers on my boat very frequently who don't know how. I try to educate these folks with the old mnemonic lefty Lucy/Righty tighty. Facing the valve handle -- turn left to open . right to close. Most people get it.....so I continue to teach it. DiveTub April 14th, 2003, 07:03 PM Capt Jim Wyatt once bubbled... but I am not sure if its in the "official" PADI cirriculum or not. I have never heard of a valve getting stuck open due to this...but its just something I have always done. It may just be superstitious behavior I have the manuals in front of me now PADI TecRec is all valves open all the way. Reasoning for this is if you have to shut them down they will only go one-way, that is you are not going to get confused and turn them on rather than off, wasting time during the shutdown. I have all mine wide open. DiveTub April 14th, 2003, 07:07 PM Capt Jim Wyatt once bubbled... that people do not know how to open a valve/close a valve. I see certified divers on my boat very frequently who don't know how. I try to educate these folks with the old mnemonic lefty Lucy/Righty tighty. Facing the valve handle -- turn left to open . right to close. Most people get it.....so I continue to teach it. Yep all good in recreational diving, but at 180Ft narced off your brain, with a HP Oring blowing out behind your head and spewing your air all over the shop, I like to know that when I turn the valve it is going to be shutdown. crazyc April 14th, 2003, 10:44 PM Here's something else to throw into the discussion. If you leave them completely open without play, there is a chance that someone can strip the valve handle. Using the wide open with no play philosophy, my buddy cranked his so hard in the wrong direction when under a bit of stress, he stripped one out completely underwater and I had to help him with the other. I have found 1/4 turn back to be "comfortable" for me. Besides, I always dive a mix that will prevent me from being narced at whatever depth I am diving, and I practice valve drills religiously. CrazyC Aquamaniac April 14th, 2003, 10:58 PM crazyc once bubbled... Snip.......... my buddy cranked his so hard in the wrong direction when under a bit of stress, he stripped one out completely underwater and I had to help him with the other. snip................ Once again, a fix for a non-existant problem. The problem was your buddy not being familiar with his gear, not the gear itself. crazyc April 15th, 2003, 02:24 AM You're correct in the fact he was unfamiliar, it was during his initial training with a manifold. However, after the dive when we debriefed, he said what confused him was that he had tried to turn the valve the way he thought it needed to go, and when it wouldn't turn, he reversed the direction. At this point he stripped the valve on his left post Since he had also just completely opened his right post, he ran into the same confusion and locked the valve knob up so hard, I had to "unlock" the knob for him. So in the following days, he adopted the 1/4 turn back on all valves, and there was never a repeat problem. I guess like som many things, it's all about what you train with and get used to. Jonathan April 15th, 2003, 02:52 AM for my two yen... I was taught to have the isolator open a couple of turns and cank the valves back 1/4 turn. Really not sure how you are going to "roll off" the isolater unless you are going grab like across the cave or wreck roof, even then you would need to try really hard. On the valves I can see that you can only go one way to close them but I don't think you lose much time if you go a quarter way the wrong way. BTW - PADI for the valves and TDI for the Isolator which has not been contradicted by further IANTD training. Jonathan crazyc April 15th, 2003, 04:04 AM Hey Jonathan How's it going up north? I heard that IANTD is teaching having the isolator on just a couple turns these days. Back when I took IANTD courses, I was taught on independent doubles. I shudder when I think about it and see any photos of myself underwater from that time frame. CrazyC WYDT April 15th, 2003, 08:46 AM Sydney_Diver once bubbled... I have the manuals in front of me now PADI TecRec is all valves open all the way. Reasoning for this is if you have to shut them down they will only go one-way, that is you are not going to get confused and turn them on rather than off, wasting time during the shutdown. Glad to see PADI got ONE thing right... LOL!! Sorry but that was just sitting there on a tee. ;) detroit diver April 15th, 2003, 09:00 AM Sydney_Diver once bubbled... Yep all good in recreational diving, but at 180Ft narced off your brain, with a HP Oring blowing out behind your head and spewing your air all over the shop, I like to know that when I turn the valve it is going to be shutdown. 180 feet narced off your brain? You've got more problems than just a valve issue here. Deep air diving, I presume? Jonathan April 16th, 2003, 01:05 AM so well I've decided to stay a bit but I think my last course here will be when I hand in my exam for tecnical diver next week. Then I start paying for the courses for the other half if I want her to go on holiday with me.... To be honest I don't know if that is the IANTD way, just that the instructor has never contradicted me. That's the way I was taught by a TDI instructor in the UK. Jonathan DiveTub April 16th, 2003, 01:49 AM detroit diver once bubbled... 180 feet narced off your brain? You've got more problems than just a valve issue here. Deep air diving, I presume? LOL and they would be ? or shall we start another thread for this :boom: The cost of helium in Aus makes it almost impossible to dive Mix for all but the super rich diver. SimonN April 16th, 2003, 02:01 AM I dive with the isolator three turns open. Any problems, I turn the isolator off first, then the offending reg and then reopen the isolator. Why? While the isolator is open I'm losing gas from both tanks. If I make a mistake and turn the wrong reg off for some reason then I lose a lot more gas in total. If I turn the correct reg off I have only lost little more gas than I would have otherwise, specifically because the isolator is only a little open. The argument GI3 gives for having the isolator open completely so you don't get your mixing wrong is a bit strange. Just open it fully when you do your mixing. MikeFerrara April 16th, 2003, 06:53 AM SimonN once bubbled... I dive with the isolator three turns open. Any problems, I turn the isolator off first, then the offending reg and then reopen the isolator. Why? While the isolator is open I'm losing gas from both tanks. If I make a mistake and turn the wrong reg off for some reason then I lose a lot more gas in total. If I turn the correct reg off I have only lost little more gas than I would have otherwise, specifically because the isolator is only a little open. The argument GI3 gives for having the isolator open completely so you don't get your mixing wrong is a bit strange. Just open it fully when you do your mixing. The valves on my manifold only go about a turn and a half from full open to full close. I think the most common failure is goint to be a hose or a reg (free flow) and then you usually know where the problem is. I guess if you can't tell it is a good idea too shut the islolator. crazyc April 16th, 2003, 07:53 AM All valves open full and back quarter turn. If you have a failure and cannot determine which side it is coming from, start with the right post. Shut it down and breathe the primary regulator down and switch to backup on left post. This way if the sound of bubbles stops, you know it has to do with the right post regulator. If it continues with the right post off, then shut the isolator. It will take a bit for the tank to empty, so you will hear bubbles for quite a while. In the mean time you should have gotten your buddies attention by now and he can inspect to see if it is a manifold failure or if it is actually a left reg failure. At this point in time he will ensure that you are on the correct regulator (making you change if neccesary) , ensure that the failure is isolated, inform you of where the failure is and turn or thumb the dive. At this point you will do a quick check of your valves to ensure they are in the proper position to isolate the malfunction (based on what your buddy communicated to you), check pressure (if it isn't a left post failure) and head back or up. If you can hear it is a left post failure then start with the left post. Basically for the sake of making this second nature, if the failure point is unknown start from the right and work your way left. If it winds up being a right or left post failure, you are not going to benefit from starting with the isolator. Plus the amount of gas lost will determine if the dive can be continued or should be turned or thumbed. And it all comes down to practice, familiarization and standardization with your equipment (you and your buddy) and maintenance of the gear. MikeFerrara April 16th, 2003, 08:07 AM crazyc once bubbled... If it winds up being a right or left post failure, you are not going to benefit from starting with the isolator. Plus the amount of gas lost will determine if the dive can be continued or should be turned or thumbed. If there is a failure and the problem can't be fixed the dive gets turned. Without an alternate the dive gets turned. What did I miss? crazyc April 16th, 2003, 08:16 AM If it is a right or left post fixable failure...eg...a seating problem or loose hose (both which can be tightened by the buddy), why turn the dive once it has been corrected if ample gas remains? Either of these failure will use very little gas. Aquamaniac April 16th, 2003, 09:55 AM Sydney_Diver once bubbled... LOL and they would be ? or shall we start another thread for this :boom: The cost of helium in Aus makes it almost impossible to dive Mix for all but the super rich diver. The last price I got for a mix in Perth was $180 for a set of doubles............ Dryglove April 16th, 2003, 12:30 PM Aquamaniac once bubbled... The last price I got for a mix in Perth was $180 for a set of doubles............ Yikes!! you gotta be kidding :whoa: Scubaroo April 16th, 2003, 12:56 PM lal7176 once bubbled... Yikes!! you gotta be kidding :whoa: This is what I calculated in July 2002: http://www.scubaboard.com/showthread.php?s=&threadid=11919 Lends a lot of credibility to the arguments CCR divers use down under to justify spending thousands on a rebreather - a year or two of diving CCR, and they've spent the same amount for the rebreather that an OC diver would have spent on just mix. SimonN April 16th, 2003, 07:11 PM lal7176 once bubbled... Yikes!! you gotta be kidding :whoa: Nope. He is $0.07/litre. Set of twin 232 bar 12.2L fabers (100cufts) with 16/45 = 232 * 12.2 * 2 * 0.45 * 0.07 = $178.32... and then you have O2 and air on top of that. To get the same tanks filled with air... $10. With EAN36 ~$20. A 3L 232 bar diluent bottle filled with 10/50 heliair would cost 232 * 3 *0.5 * 0.07 = $24.36. The CCR divers I know say that will last the about 3 to 6 dives. So, by using a ccr you are saving about $150 a dive, call it $100 to allow for O2, scrubber and maintenance. A well known CCR costs $13500 with training, so you will make that back in 135 tech dives. I do about 60 tech dives a year. I have plans to buy a KISS (~$10000 for the whole 'project'). -BlueHole- April 16th, 2003, 07:30 PM Would be a bad idea to keep the isolator closed and to open it every 30-40 bars ? So in case of free flow you would always have one "sure" tank ? WreckWriter April 17th, 2003, 08:35 AM -BlueHole- once bubbled... Would be a bad idea to keep the isolator closed and to open it every 30-40 bars ? So in case of free flow you would always have one "sure" tank ? Yes, it would be a bad idea. WW Aquamaniac April 17th, 2003, 08:49 AM -BlueHole- once bubbled... Would be a bad idea to keep the isolator closed and to open it every 30-40 bars ? So in case of free flow you would always have one "sure" tank ? Thats almost as silly as wrapping your bouyancy device up in Deflation Cord................ -BlueHole- April 30th, 2003, 09:44 AM WreckWriter once bubbled... Yes, it would be a bad idea. WW Could you please expand the argument ? WreckWriter April 30th, 2003, 09:53 AM -BlueHole- once bubbled... Could you please expand the argument ? Sure, its a bad idea because it adds task loading and fixes a non-existing problem. The argument against doing this is the same as against wearing fully independant doubles. WW dtdiver May 2nd, 2003, 05:32 AM how many turns do your valves take to shut or open? i am doing my tech training with one that took me about 15 "spins " of the knob to shut it off trying to complete the shutdown and reopen of the three valves in 1 minute leaves me wheezing part of my difficulty could be that with short arms i can't get a lot of leverage on them thanks for any info dt Aquamaniac May 2nd, 2003, 08:30 AM My Valves are 1 1/2 turn to shut down. Im only guessing, but I think i can do 1/2 a turn each "spin" so I figure 3 "spins" and Im done.
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