That sign at the beginning is "current", I've seen it and used it many times in Europe and Asia. It's always fun when you signal "come closer, current's getting strong" as it looks like you're saying "come here, I'm gonna beat you up" LOL
It makes sense for it to be current based on his previous two signals...the way I see it is he said: "The boat is that way, we have to swim, against the current" - at least that's how I read it now.
It means "swim against the current". There is another version, where instead of punching your palm, you indicate with two fingers on the palm to say "swim with the current".
I don't even dive, but this is currently my favorite youtube channel. You guys make me want to go diving! Probably no caves for a me, but I love that I can tune in here and enjoy it anyway!
Don't say never. ;) I've been diving for two decades but a lot more actively the past few years. As my skills have grown so has my interest to go into technical and cave diving. Years ago I wouldn't have even considered it. I hope you'll do a try dive someday soon. :)
@@DIVETALK dudes calmer than a bucket of ice. I was just waiting for him to deploy his SMB as well. Hahaha! Guy definitely shows how important it is with training, practicing skills and different scenarios. 👌 That's the guy you want as a buddy when things goes wrong. The girl did a great job staying calm and being ready with the octo. Great team together!
The fish is so that he can be identified by the other divers as their guide. Seen that on a lot of guides (with duckies or other things). Really helps especially when you run into another dive group so you can always identify your guide.
@@DIVETALK Nudge, nudge :) Would love to see a vid like this. Just to add to the conversation at the end as an amateur diver but also as an engineering student: I would actually guess that at a greater depth, the time before all of your air escaped the tank would be longer! It's all about the pressure delta. Using the Navier-stokes equation, you can remove the friction and stress terms to get Bernoulli: v^2 = 2(deltaP)/D Where v is velocity, deltaP is the pressure difference between the tank and the outside pressure and D is density of your gas. It of course isn't 100% accurate because it is just an estimate of what would happen in an ideal world in a hypothetical tiny point of gas flow, but it still shows the relationship between deltaP and velocity pretty clearly. Of course, none of this takes into account that you have to breathe and consume higher amounts and greater depths, but that's a bit harder to estimate.
I went diving after watching this video. During the dive we heard this extremely loud bang. Since I watched this video I thought maybe something similar happened. Checked myself and my buddies, we were all good so continued the dive. Turns out that the military had set off a bomb which was what we heard. 😂
Thank you for these videos/reactions. Your professionalism, knowledge, and passion for diving is contagious. It’s is comforting to see how serious you take it and also how you remain humble and teachable. You’re leading the way to a new generation of divers. Keep it up!
4 weeks, no dislikes, I can say that out of all of my years of professional TH-cam watching I have never seen such a thing. The algorithm should be strong with this one.
This diver is a real hero👌👌Calm, focused, and you can see he is a really skilled diver! Thanks for the video guys, and the accurate explaine! :) We are waiting for the next video! :) 👌👌 Safe Dive! 👌🤘
I found you through Mr. Ballen..now subbed and loving your vids! I would be so interested to seeing you two react to the Thailand rescue of that soccer team!
Hello Gus and Woody, My take on the bleeding air issue is this; At 10 feet you are at 1 atm plus whatever 10 feet is of pressure pushing against the tank pressure. If it takes 55 minutes to bleed high-pressure through a high-pressure orifice and three minutes to push high-volume air out the low pressure hose, at 100 feet you are at 3 atm so three times the surface pressure pushing against the tank pressure. This will slow down the volume of air exiting the tank. This assumes you’re doing the cut hose test. The reason this is opposite for regular diving is due to the fact that you’re second stage works on suction in conjunction with pressure as you are sucking on your regulator to allow the demand of air to flow into your lungs. This consumes more air volume than a low pressure open hose. (vacuum + pressure)
About the tank opened depper, it would actually empty itself slower : if you were to open a 200 bar tank in a 200 bar environnement nothing would come out of the tank because there would not be any pressure difference. Worse if you were to open it in a 200+ bars environement it would fill itself with water. The pressure difference decides of the flow, the less pressure difference, the lesser the flow. That's also way you have to "work" harder to breath at higher depth, you need to create the pressure difference between your lungs and the environement. It gets harder and harder the deeper you go. You still have to create that ~6L of empty space in your lungs to breath so your muscles need to push against the environement. And those 6L will be filled with higher pressure gas, because it would be too hard for your muscles to keep a low pressure in your lungs. So you consume more because you have the same volume to fill but at a higher pressure. Great video guys, a pleasure to watch!
Hey guys! Love the channel! With regards to why a tank would run out faster through a low pressure hose vs a high pressure hose, you are totally right about it coming down to the size of the orifice in the line. I believe both situations would be a situation of choked flow (although I didnt run through the calculations to confirm). Without going into the weeds too much, its essentially caused by the Venturi effect, which says that when a fluid goes through a constriction with lower pressure on the outlet, the velocity of the fluid will increase. Choked flow is a limit of this principle where mass flow cannot increase any more unless the pressure on the outlet decreases. The mass flow is directly proportional to the cross sectional area of the orifice.
Just for info, in the original video they are saying it was indeed a LP hose exploration that happened at 10m deep at the beginning of the dive. So that’s why they did not worry about deco. (And the dive place was in Philippine where material hazard is unfortunately usual)
Been diving since I was 11 yrs old - currently on advanced open water which i got when I was 15yrs old, I might be wrong but to my knowledge: 1. The punching sign on palm means either we’re going to swim against the current or like danger stone fish thing. 2. Thumbs up - actually means go up / abort dive. The lady is signaling is saying the group just comes up. The beeping side must be the man’s dive watch signaling a safety stop. 3. Good that he’s maintaining bouyancy. what people dont see is his buddy gave him the octopus so he can shareair while they do a safety stop so he doesnt depend on the original tank. See the yellow thats second stage for emergency. Doesnt look to be deep enough. Like around 0-30ft. 4. Ive experienced this, like literally my dad and I were I at 60-70ft he literally ran out of air i had to crawl and he didnt have to signal he forgot to check his gauge and i literally got my octous and slapped it on his mouth. We still were able to do a saftey stop at 20 ft. Faster than normal ascend obviously, but still had 400 psi left on the tank. I had 1800 left and had to calm my dad down. I always save air for emergencies like these. You’ll never know. What I’ll never repeat would be cave dives. I remember the cave dive plan goes as deep as 80-90ft and there are 3 air pockets in between that we went through, flashlight went out. No sweeper, Couldnt see until I remembered I have a strobe on my camera rig, turned it on from sleep pressing random buttons and was able to turn on video, then got some light last thing I saw was 2 small bubbles and just swam to it calmly until finally saw more bubbles then glad I was back with the group
Always love your videos. Crazy informative. I never even considered diving before i found this channel but im 100% confident to actually learn one day now because of you guys.
I'm a bit late to the party, but my thoughts regarding the change of flow speed in relation to depth: The added air consumption at depth is only related to the fact that you need more volume to fill your lungs against the pressure at depth. But because the increased water pressure means a smaller pressure delta between tank and environment, the flow speed should be slightly lower at depth. However, with a full tank that difference is pretty marginal, e.g. (10 meters) 200 bar - 2 atmospheres of pressure vs (110 meters) 200 bar - 12 atmospheres - which is probably already to deep for this kind of test.
That sign normally means there is some current. This happened to me in Ko Tao - Thailand, with my yoke 1st stage - a reason why I swapped to a DIN 1st stage, much less likely to happen. I had enough time to check my regs, put BCD back on, deploy DSMB, breath from my own air while checking SPG and do my safety stop while having a buddy closely incase I need air. First of all kudos to the guide for handling the situation including the other divers and remaining calm. We can clearly see that he had the situation under control, again big plus on here!! Unfortunately I missing a safety stop and a DSMB deployment here. Now we can give him the benefit of the doubt, as we can't see the whole picture, this was probably the end of the dive, the safety stop might have been concluded already, and another diver might have already deployed a DSMB. But it's important to mention that even if this happens, you are still able to deploy you DSMB and do your safety stop. great job on the video breakdown, thx so much for the content.
Yea I pay YT extra to not have commercials says me a lot of time and I have ADD so would lose focus with too many commercials. I stopped watching TV 10 years ago for this reason.
I think cutting a hose at a lower differential pressure between the tank and the exterior of the tank would take longer than at atmospheric pressure, in other words it would take longer to empty the tank the deeper you go, we are not talking about breathing from the tank here , just a pressure release time.
Found this channel on my recommended and I've been addicted to it. Every video I watch I learn something, great channel. My mom and I are open water divers and my dad is a divemaster. Diving is awesome and I love it, it's like stepping into another world. One question do yall spearfish?
Hi guys, just wanted to make a guess at the flow of air out of a pressurized tank at different depths. Something to consider is that the tank is relatively static, and the internal pressure doesn't change much when taken to depth. The ambient pressure increases a lot, so the pressure gradient, difference between inside and outside, is growing smaller the deeper you go. (i.e., net force decreasing) My conclusion is that the air will come out slower the deeper you go. As for increased consumption at depth while diving, this is due to higher demand from the regulator, opening the flow closer and closer to max flow. Imagine having a regulator and you dive really deep; does it get harder or easier to draw air from it, and do you have to adjust your regulator to restrict air flow, or open up more and allow more air out of it (closer to unrestricted flow) with each inhalation?
This is assuming you dive with a balanced first and second stage, otherwise you already know from using an unbalanced system that it can be very hard to draw air out of the tank when you go really deep and it's unlikely you could forget the growing panic as the effort to breath is becoming too much.
As a final proof of concept I will give you an argument ad absurdium: imagine taking a tank to a depth where the ambient pressure is greater than 200 atm. There would be literally no flow out of the tank with an open line, because there is no pressure difference between the inside and outside of the tank.
These are the types of persons I like doing excursions with... cool headed, calm and collected. Panic never helps you or anyone survive. I've been on enough adventures with folks who were not mentally fit for demanding situations and I don't ever do that any more. I don't go on adventures that will almost surely be very demanding with people I don't know and or who I already know can't handle themselves, I'd rather stay home. Having well suited individuals around you who know what to do and how to act if things go sideways always makes for a much better and enjoyable experience even if things do end up not go according to plan. I don't know who he is, but much respect to this guy who made a tough situation look easy.
If the guy has a wing and a second stage with a swivel it's not his first picnic. The high-pressure hose is for your pressure gauge only so the inside diameter is like a needle. If you try it, your tank will need a visual inspection after.
we do use that fist against palm signal if there is a lot of current. usualy when there is to much current for a diver, they give that signal. meaning you are swimming against a wall, staying in place instead of going forward. doesn't seem a lot of current in the video though.
A year ago I had a similar situation. It happened at the beginning of a dive at 16 m. It was an yoke valve and I lost almost all my air in less than a minute before my instructor geve me his octo ant shut my tank down . Soon after, we found out that there was nothing visible wrong with the o ring. I heard from other instructors that they've witnessed the same thing. They say that the o ring on yoke valve can get displaced and that happens usually in the first minutes of a dive.
Love the videos, I haven't dived since I was a kid and watching the videos makes me wanna get into it again so much. I did a university report this year on Bernoulli's principle and I didn't think I'd see a relevant use for it so soon, so basically with fluids including air. Pressure and velocity are inversely related, so the higher the pressure the lower the velocity and vice versa. I sum it up really quick and Im far from an expert on the subject but I reckon that would explain the 55 mins, 3 mins and 13 mins situation. Im guessing the pressure straight from the o-ring would fall somewhere between the high and low pressure hoses and therefore the velocity would fall somewhere between the 2. Love the videos, If I give you guys something to look up and research Im happy lol, you guys have brought a passion back for going diving in me so thanks man.
I think cutting a hose at a lower differential pressure between the tank and the exterior of the tank would take longer than at atmospheric pressure, in other words it would take longer to empty the tank the deeper you go, we are not talking about breathing from the tank here , just a pressure release time.
@@guslevesque9369 I doubt it makes a noticeable difference. The difference in tank pressure between a few hundred bar and the environment (at most 5 bar) is too large to have any slowing effect.
The LP hose getting severed will leak a tank empty marginally faster than a severed HP. The HP has marginally less flow, pay close attention to the HP port and the end of the HP hose and it’ll make sense. Deeper depth will cause the tank to drain faster in a severed hose scenario but not for the the reason you suspect. The additional ambient pressure on the tank itself does not “squeeze the gas out faster.” The leak will speed up at a deeper depth because the 1st stage is always automatically compensating for increased ambient pressure, it does this by increasing the flow to the LP ports (it should not increase pressure much, just flow).
@Dive Talk I once had a buddy whos o-ring blew up under water. We jumped into the sea a fair bit off the reef (after taking a compas course to the reef), as we were preparing to go in looking for manta rays. We saw them from the surface and decided to go in with them and then back towards the reef. Busy area with lots of boats, so we all went straight down to ~15ish meters. Only 2-3 minutes into the dive I look at my buddy as theres loud noice and see bubbles flowing. Shes even more confused than the guy in this video, thinking its a speedboat going over us or something similar. When I check whats going on I see bubbles flowing from the tank valve, so I check her air gauge and offer her my octo, whish she shrugs at, until I show her how fast her gauge needle is moving. She take my octo, I turn her tank off, trying to reseat the first stage as I thought maybe it wasnt properly seated and realize the o-ring is screwed. From the time I saw bubbles to the time I shut her tank off, maybe 2 minutes had passed and she was down to 120 bar in her tank. Grabbing each others bcds and her breathing from my octo we held the depth (due to the busy area above), swam back to the reef, did our safety stop and was back out of the after 10 minutes. 300+ dives ago its still one of the more interesting ones. Helps that the few minutes we got was with 3 manta rays of course.
I'm no physics or diving guru, but I think Bernoulli's Principle in flow dynamics may apply here. The increase in the loss of air in the low pressure hose is further enhanced by the large internal diameter of the hose in comparison to the HP hose. Bernoulli's principle states that an increase in the speed of a fluid (applies to gas as well) occurs simultaneously with a decrease in static pressure or a decrease in the fluid's potential energy.
HP hose is very thin. It is only to transfer the pressure. I had spigot o ring failures recently. It must have been the time. when I noticed them in the water, I am usually like, I will finish the dive and sort it out at my surface interval. I am usually not worried about high pressure. I had both failure on my right post 1st stage and my left post-low-pressure hose both at the same time. Luckily it was only at 2m deep, the beginning of a dive. It did not take very long! Maybe 3 minutes like you said. I did the live valve drills only to notice the leak did not stop until I turn all valves off. It was sad.
The air in the LP hose would generally come out more slowly at a greater depth. We know the reason you use air more quickly when you are deeper is because the 2nd stage supplies you air at the ambient pressure. So when you are deeper you draw air out at a higher pressure. But the pressure internal to the LP hose is regulated only by the 1st stage (100 -150 PSI depending on your regulator model). So in that case the flow out will be determined only on the pressure differential between ambient and the LP supply pressure. So if you are deeper, that differential will be smaller. Some higher end regulators will increase the LP supply pressure as you descend in order to compensate for the decreased pressure differential at depth. So results will vary.
The tank valve has a 1st stage that drops the low pressure hose to 125 to 150 psi., before it reaches the regulator. So at 100 ft.(4 bar), roughly 60 psi, the open low pressure hose into 100 ft. deep water has an effective pressure of 65 to 90 psi. I'm guessing with the hose cut, it would free flow about 5 minutes and 23 seconds.
14:18 it's a bit late but i don't think there would be a big difference because the reason you breathe more air the deeper you go is because of the second stage hence if you cut it before the second stage it would empty at the same rate as the pressure the first stage could provide which is fixed.
On the LP hose failure at depth. Your low pressure hose is still a higher pressure than your surrounding environment. So the depth won’t decrease the total bleed time of your cylinder.
AT least one diver had a A-Yoke first stage, and those are pretty prone to blow an o-ring. Since he could turn the valve off and the leak stops means it was not a tank neck blown o-ring The description says something about 200bar, which increases my thoughts that it was a A-Yoke first stage I moved to DIN valves/regulators to avoid this kind of scenario John
Maybe you have seen or already know this but I believe they have done this test by lake hickory scuba and there are 2 tests to I remember correctly. Love watching you guys always entertaining and good info to talk about.
To add some info: In the description (in french) it is said that it was at the beginning of the dive (might explain no stop) and that it was from the LP hose to the second stage. It looks like loose part in the first stage to me (sometime happen in the part receiving air from the tank) but it doesn't look like the valve. Don't you think he could have done some valve fluttering to improve his situation if the problem is after the valve ? Still, he looks very calm and managed to get out of water with everybody.
I believe the hand signal at 1:37 means current. I've used it a few times but I'm not sure if that's pretty international (I'm from Spain btw). It seems that the guy is telling where the boat is and that they have to swim a bit because they drifted with the current.
My regulator mouth piece froze up @ 98ft. I was with 10 people including an instructor at Dutch Springs PA in the middle of winter. Water temps low, don't remember how low. One second, I was checking out this big truck, then suddenly air started pouring out my mouthpiece and I accidentally hit my mask and they flooded. super scary. I honestly thought I was done for. But the instructor quickly grabbed my bcd by my chest, took my hand and placed a regulator in it. I take a breadth of the regulator and somehow water snuck in, I started choking but I forced myself to cough in the regulator and eventually continue breathing. I could feel we started to ascend(remember my facemask was full of water.). On the ascent I finally cleared my mask and started to feel much better. I'm just glad I was with a good instructor and glad I didn't panic(I mean "apparently panic", cause I for dam sure was panicking but only in my head).. I read later this can happen but I was unaware before the dive. Now I know why the instructor carried an extra pony tank with him on the dive..
@@TH-camWatcher29 in Europe we use 2 1st stages with a 2nd stage on either in the colder months. These 2 1st stages would be connected to a K- or H- valve on a single cylinder. Same principle when diving Sidemount or Twinsets, you have redundancy. Also, the 1st and 2nd stages would be designed for cold water. This way, a pony would be obsolete
If you haven't already, would love your reaction on this: th-cam.com/video/v5oUxJX1Uqo/w-d-xo.html Does the fact that the structure is man made and being explored by a professional free diver change your thoughts on things like lights, guide lines, etc.?
just comparing basic pressures, i think the time to empty a tank with a LP hose cut at 10ft and at 100ft would be almost the same. at 10ft you have 1.3atm or about ~20psi, at 100ft you have about 4atm or ~60psi, either of those compared to 3000 psi in the tank is basically nothing, so the air will escape at almost the same speed at both of those depths. i might be overlooking something though.
Speed to empty the tank depends on delta P between the tank and ambient pressure. So the deeper the slower. You can imagine that at 230 meters the cylinder doesn’t even leak.
1:20 you can see something white floating behind his head above his back (the guy that gives the signs). It’s maybe supposed to be floating like that but I don’t think I have ever seen that before. And when he quickly turns around, it looks to me like, he might have touched the string between himself and that white floating thing, and maybe it got pulled out of whatever it was attached to on him??
I have had my O ring pop at 30 ft during a drift dive. I thought a boat started its engine over me. I took my buddy's Octo and did just like that guy, shut my tank, slowly got to the surface. Reset the O ring, then we went back down to finish the dive. I do hope you guys do the test. But maybe just leave the ports without plugs and open the tanks at 100 feet, instead of cutting the hose.
for us who dive open water the plan is to always get the explosive off your back ... hold it at a distance if it does go ( boom ) the concussion will not blow out your ear drums if it was not the first stage ... remember sound travels 7x faster underwater and so does concussive force...
if you were to cut LP hose on a balanced reg, air will come out the same at 10ft as at 100ft, since the reg will compensate for depth to always deliver 150psi. if it's an unbalanced reg, air will come out slightly slower at 100ft because it'll be fighting the ambient pressure, so instead of 3 minutes, maybe it will take 4-5.
I'm just thinking through what to do if that happened solo at 70ft. In my dive-class, we did something similar in my dive-class breathing from the regulator while it wasn't in our mouths, while in a pool at 10ft. So maybe you could remove the BCD, close the valve partially, and then breathe the bubble-stream. You're still losing air fast, but could potentially have enough to deco.
I really like how that came together about the HP and LP valves. Because I thought the same thing as Woody but once I saw the valve openings it made total sense.
I would very much love to watch videos where these two test equipment failures and how long befor the tank empties at different depths etc. Also the person in this video was so calm. Much respect to them for not shitting themselves and going full panic mode
Such a great video! I'm a newer diver, and these videos are incredibly helpful (and entertaining)! I learn so much each time I watch your content. Keep the awesome videos coming!!!
Sounds like an interesting test. If you have a balanced first stage it will adjust to the surrounding pressure so the breathing resistance (mediate pressure) is the same almost as at the surface. So it will probably go faster than at 10 ft at 40 ft but I don’t believe you will have that big change. The flow ought to be almost the same. Hose haven’t changed the mediate pressure is the same. For most regulators around 9-10 bar. So why should it go so much faster?
Thank you for the video. Flow rate is a function of supply pressure, and orifice (opening) size. The 55 minutes for a high pressure line would be at any depth. The high pressure isn't modified by the regulator. The 1st stage intermediate pressure is affected by depth. At 99 fsw your intermediate pressure is 58.8 psi greater than at the surface. Your going to lose gas faster at depth. Whether you are losing gas because of breathing or a failed low pressure hose it goes faster at depth.
Ive had this happen twice with the Orings blowing on hired tanks and it goes off with a bang, both times my buddy was close and heard it then we were able to do a slow/safety stop accent ( I always double check the Oring now ) But if the hose fails at the SPG or 2nd stage is it possible to kink the hose off? Maybe something you guys could try if you're doing the cut hose thing. Like what you do. Cheers.
What pressure is there in a low pressure hose and what does it depend on? I thought there was intermediate pressure and the second stage adjusts to ambiant pressure. So the pressure in the low pressure doesnt really depend on environmental pressure but is around 8 bar. That would suggest that the time you have doesnt really change.
The LP hose is always at roughly 100psi. So if you are at 3atm, the flow will be much higher, so you loose air faster. You will loose gas faster if the whole reg is off. No need to cut the hose. Just take down a wrench, depressurize, pull the spg off (don't loose the spindle). For the lp side, just hold open the bcd inflate and vent at the same time.
@@DIVETALK Hard to argue with that! Be sure to keep your hands clear of the cut on the high pressure side, and use ear pro if you do it on the surface. Looking forward tonthe video!
It's gotta be an O-ring but I can't imagine how it would rupture like that? Props to the diver, very cool-headed. I think you're right, at 100ft the air would be gone in under a minute.
@@DIVETALK really? I'm having a tough time wrapping my head around this one. I would've thought it would be faster under pressure. Good job I haven't dived in years. I think I need to brush up on my Boyle's Law! lol Thanks for the reply. Enjoying your videos. Cheers!
This might be a dumb question, but couldn’t you fit more gas into a tank if you filled it in a pressurized environment? Or would it just rupture when brought back to normal atmosphere before being used? (I’m obviously not a diver, just fascinated by these videos)
The pressure differential from the regulated lp hose to the water should decrease the further you go down, thats at least what i think. So at the same time the rate of flow should decrease. As far as i know the first stage outputs basically a static pressure of about 140 psi to the lp hose, which only fluctuates due to load(breathing, bcd inflation, etc). I might be wrong here.
I think that you would be surprised at lower depths that it may not come out x atmospheres faster. Because the water pressure is so much higher, and since the tank is no longer a rigid closed body that has its own pressure environment (the water can now directly push on the air and affect the pressure), I think that even though MORE air might be contained in each bubble of air, the rate at which these bubbles want to escape will be reduced. So it would be very interesting to see, and to see which force overcomes the other. I suspect it will come out still at a faster rate, but definitely not scale linearly (i.e. 2x atmosphere = 2x faster or y=a*x). It may be more inverse quadratic, i.e. y=a*sqrt(x)
I think the LP hose at 100 feet would come out slower than the surface because it's not going through the depth compensation of the second stage, hence the gas would be fighting the water pressure at depth.
That sign at the beginning is "current", I've seen it and used it many times in Europe and Asia. It's always fun when you signal "come closer, current's getting strong" as it looks like you're saying "come here, I'm gonna beat you up" LOL
It makes sense for it to be current based on his previous two signals...the way I see it is he said: "The boat is that way, we have to swim, against the current" - at least that's how I read it now.
@@DIVETALK Yes, that's what it looks like. "You'll need to kick your way to the boat because there's some current"
It means "swim against the current". There is another version, where instead of punching your palm, you indicate with two fingers on the palm to say "swim with the current".
In Indonesia we use the sign for strong currents... So he's saying currents are strong and we have to swim against the currents to reach boat...
We use that sign for current too. Wherever your punch comes from indicates where the current is coming from. Left, right, down under etc
He’s actually having to calm the people who aren’t in danger. They’re like trying to panic on his behalf...
He was amazingly Calm.
That guy was unbelievably calm. The way the slipped out of the gear and turned it around to check was really slick
I don't even dive, but this is currently my favorite youtube channel. You guys make me want to go diving! Probably no caves for a me, but I love that I can tune in here and enjoy it anyway!
Awesome!!! Thanks so much.
I’m the same, they make me want to pick up diving. Feel like I wouldn’t be going in blind if I do decide to try it.
Don't say never. ;) I've been diving for two decades but a lot more actively the past few years. As my skills have grown so has my interest to go into technical and cave diving. Years ago I wouldn't have even considered it. I hope you'll do a try dive someday soon. :)
You won't regret it! The underwater world is beautiful!
Go for it! You'll never regret to do that 👌👌👌
These guys complement each other in a knowledgeable, hosting mentality very well. Positive impact to both experienced and beginner divers alike
Made our day. Thank you!
Looks like the o-ring popped. Gotta give the guy some cred for being so calm.
Agree
@@DIVETALK dudes calmer than a bucket of ice. I was just waiting for him to deploy his SMB as well. Hahaha! Guy definitely shows how important it is with training, practicing skills and different scenarios. 👌 That's the guy you want as a buddy when things goes wrong. The girl did a great job staying calm and being ready with the octo. Great team together!
dude was more laid back than an ironing board
MAYBE he pops a xanax before diving? Lol
@@chronicawareness9986 Hahaha!
The fish trinket hanging from his BCD is a regulator holder lol, I've seen these before at my local dive shop
The fish is so that he can be identified by the other divers as their guide. Seen that on a lot of guides (with duckies or other things). Really helps especially when you run into another dive group so you can always identify your guide.
DM: “Chill out, this happens all the time. I’ve got this.”
Ha exactly!
The level of calmness was almost he was about to roll his eyes. Like, aaa-gainnnn?
Can’t wait to see the footage of y’all testing this!!
Ha yikes.
C'mon you need to do this.
Nudge🤗 would really like to know what happens. My money is on it taking longer at depth
@@DIVETALK Nudge, nudge :) Would love to see a vid like this. Just to add to the conversation at the end as an amateur diver but also as an engineering student: I would actually guess that at a greater depth, the time before all of your air escaped the tank would be longer! It's all about the pressure delta. Using the Navier-stokes equation, you can remove the friction and stress terms to get Bernoulli:
v^2 = 2(deltaP)/D
Where v is velocity, deltaP is the pressure difference between the tank and the outside pressure and D is density of your gas. It of course isn't 100% accurate because it is just an estimate of what would happen in an ideal world in a hypothetical tiny point of gas flow, but it still shows the relationship between deltaP and velocity pretty clearly.
Of course, none of this takes into account that you have to breathe and consume higher amounts and greater depths, but that's a bit harder to estimate.
I went diving after watching this video. During the dive we heard this extremely loud bang. Since I watched this video I thought maybe something similar happened. Checked myself and my buddies, we were all good so continued the dive. Turns out that the military had set off a bomb which was what we heard. 😂
That’s crazy, whoa!
Thank you for these videos/reactions. Your professionalism, knowledge, and passion for diving is contagious. It’s is comforting to see how serious you take it and also how you remain humble and teachable. You’re leading the way to a new generation of divers. Keep it up!
Thanks for the comment and the support.
The flat hand with a fist going into it, signal for "current"
Thanks yes we confirmed this also.
4 weeks, no dislikes, I can say that out of all of my years of professional TH-cam watching I have never seen such a thing. The algorithm should be strong with this one.
Thanks Chad!
This diver is a real hero👌👌Calm, focused, and you can see he is a really skilled diver!
Thanks for the video guys, and the accurate explaine! :)
We are waiting for the next video! :)
👌👌
Safe Dive! 👌🤘
Thanks for the comment and the support.
I found you through Mr. Ballen..now subbed and loving your vids! I would be so interested to seeing you two react to the Thailand rescue of that soccer team!
Thanks and yes this is on our to do list.
14:00 Guys, the pressure in LP hose is set by the regulator to c.a. 10 bar above the pressure of the environment. So, it depends on the depth.
Thanks!
I get so excited when a new video is posted, these 2 need to be more popular. Such an interesting subject.
Thanks so much for the support!
Hello Gus and Woody,
My take on the bleeding air issue is this; At 10 feet you are at 1 atm plus whatever 10 feet is of pressure pushing against the tank pressure. If it takes 55 minutes to bleed high-pressure through a high-pressure orifice and three minutes to push high-volume air out the low pressure hose, at 100 feet you are at 3 atm so three times the surface pressure pushing against the tank pressure. This will slow down the volume of air exiting the tank. This assumes you’re doing the cut hose test.
The reason this is opposite for regular diving is due to the fact that you’re second stage works on suction in conjunction with pressure as you are sucking on your regulator to allow the demand of air to flow into your lungs. This consumes more air volume than a low pressure open hose. (vacuum + pressure)
You guys are awesome at video breakdowns. Would love to see you two do a series on the cave rescue in Thailand.
Thanks!
About the tank opened depper, it would actually empty itself slower : if you were to open a 200 bar tank in a 200 bar environnement nothing would come out of the tank because there would not be any pressure difference. Worse if you were to open it in a 200+ bars environement it would fill itself with water. The pressure difference decides of the flow, the less pressure difference, the lesser the flow.
That's also way you have to "work" harder to breath at higher depth, you need to create the pressure difference between your lungs and the environement. It gets harder and harder the deeper you go.
You still have to create that ~6L of empty space in your lungs to breath so your muscles need to push against the environement. And those 6L will be filled with higher pressure gas, because it would be too hard for your muscles to keep a low pressure in your lungs. So you consume more because you have the same volume to fill but at a higher pressure.
Great video guys, a pleasure to watch!
Yep makes total sense. But we still wanna try and film it lol
@@DIVETALK And I still want to see that !! haha
Hey guys! Love the channel! With regards to why a tank would run out faster through a low pressure hose vs a high pressure hose, you are totally right about it coming down to the size of the orifice in the line. I believe both situations would be a situation of choked flow (although I didnt run through the calculations to confirm). Without going into the weeds too much, its essentially caused by the Venturi effect, which says that when a fluid goes through a constriction with lower pressure on the outlet, the velocity of the fluid will increase. Choked flow is a limit of this principle where mass flow cannot increase any more unless the pressure on the outlet decreases. The mass flow is directly proportional to the cross sectional area of the orifice.
Just for info, in the original video they are saying it was indeed a LP hose exploration that happened at 10m deep at the beginning of the dive. So that’s why they did not worry about deco.
(And the dive place was in Philippine where material hazard is unfortunately usual)
That dude was so calm during this whole situation. Really top notch
Omg Gus, that was an awesome analysis of the video! You guys are amazing! Love you and much respect!
Thanks so much!! We love you too.
Been diving since I was 11 yrs old - currently on advanced open water which i got when I was 15yrs old, I might be wrong but to my knowledge:
1. The punching sign on palm means either we’re going to swim against the current or like danger stone fish thing.
2. Thumbs up - actually means go up / abort dive.
The lady is signaling is saying the group just comes up. The beeping side must be the man’s dive watch signaling a safety stop.
3. Good that he’s maintaining bouyancy. what people dont see is his buddy gave him the octopus so he can shareair while they do a safety stop so he doesnt depend on the original tank. See the yellow thats second stage for emergency. Doesnt look to be deep enough. Like around 0-30ft.
4. Ive experienced this, like literally my dad and I were I at 60-70ft he literally ran out of air i had to crawl and he didnt have to signal he forgot to check his gauge and i literally got my octous and slapped it on his mouth. We still were able to do a saftey stop at 20 ft. Faster than normal ascend obviously, but still had 400 psi left on the tank. I had 1800 left and had to calm my dad down. I always save air for emergencies like these. You’ll never know.
What I’ll never repeat would be cave dives. I remember the cave dive plan goes as deep as 80-90ft and there are 3 air pockets in between that we went through, flashlight went out. No sweeper, Couldnt see until I remembered I have a strobe on my camera rig, turned it on from sleep pressing random buttons and was able to turn on video, then got some light last thing I saw was 2 small bubbles and just swam to it calmly until finally saw more bubbles then glad I was back with the group
This looks to be in the Philippines. Many DMs use the punch sign as signal that there’s strong current.
Great video! I don’t dive but I am fascinated by every conversation you guys have! Thank you for doing this!
More to come!
The unknown dive signal means (strong) current
Gotcha. Thanks!
Always love your videos. Crazy informative. I never even considered diving before i found this channel but im 100% confident to actually learn one day now because of you guys.
Great to hear!
I'm a bit late to the party, but my thoughts regarding the change of flow speed in relation to depth: The added air consumption at depth is only related to the fact that you need more volume to fill your lungs against the pressure at depth. But because the increased water pressure means a smaller pressure delta between tank and environment, the flow speed should be slightly lower at depth. However, with a full tank that difference is pretty marginal, e.g. (10 meters) 200 bar - 2 atmospheres of pressure vs (110 meters) 200 bar - 12 atmospheres - which is probably already to deep for this kind of test.
Good job pointing out the volume thing
His fish is so his divers can recognize him.
Yep
That sign normally means there is some current.
This happened to me in Ko Tao - Thailand, with my yoke 1st stage - a reason why I swapped to a DIN 1st stage, much less likely to happen.
I had enough time to check my regs, put BCD back on, deploy DSMB, breath from my own air while checking SPG and do my safety stop while having a buddy closely incase I need air.
First of all kudos to the guide for handling the situation including the other divers and remaining calm.
We can clearly see that he had the situation under control, again big plus on here!!
Unfortunately I missing a safety stop and a DSMB deployment here.
Now we can give him the benefit of the doubt, as we can't see the whole picture, this was probably the end of the dive, the safety stop might have been concluded already, and another diver might have already deployed a DSMB.
But it's important to mention that even if this happens, you are still able to deploy you DSMB and do your safety stop.
great job on the video breakdown, thx so much for the content.
Yep confirmed . It does for sure.
“This is gonna be so much money”
Not if we ALL watch it with ads on👀
Yea I pay YT extra to not have commercials says me a lot of time and I have ADD so would lose focus with too many commercials. I stopped watching TV 10 years ago for this reason.
I think cutting a hose at a lower differential pressure between the tank and the exterior of the tank would take longer than at atmospheric pressure, in other words it would take longer to empty the tank the deeper you go, we are not talking about breathing from the tank here , just a pressure release time.
Agree
My dive instructor told me during the stress and rescue class that I have more time in failures at the high pressure than the low pressure hose.
Found this channel on my recommended and I've been addicted to it. Every video I watch I learn something, great channel. My mom and I are open water divers and my dad is a divemaster. Diving is awesome and I love it, it's like stepping into another world. One question do yall spearfish?
No, but we do kill Lionfish whenever we can.
Hi guys, just wanted to make a guess at the flow of air out of a pressurized tank at different depths.
Something to consider is that the tank is relatively static, and the internal pressure doesn't change much when taken to depth.
The ambient pressure increases a lot, so the pressure gradient, difference between inside and outside, is growing smaller the deeper you go. (i.e., net force decreasing)
My conclusion is that the air will come out slower the deeper you go.
As for increased consumption at depth while diving, this is due to higher demand from the regulator, opening the flow closer and closer to max flow.
Imagine having a regulator and you dive really deep; does it get harder or easier to draw air from it, and do you have to adjust your regulator to restrict air flow, or open up more and allow more air out of it (closer to unrestricted flow) with each inhalation?
This is assuming you dive with a balanced first and second stage, otherwise you already know from using an unbalanced system that it can be very hard to draw air out of the tank when you go really deep and it's unlikely you could forget the growing panic as the effort to breath is becoming too much.
As a final proof of concept I will give you an argument ad absurdium: imagine taking a tank to a depth where the ambient pressure is greater than 200 atm.
There would be literally no flow out of the tank with an open line, because there is no pressure difference between the inside and outside of the tank.
I know nothing about diving nor would I dare! It fascinates me & I love learning from you two!
These are the types of persons I like doing excursions with... cool headed, calm and collected. Panic never helps you or anyone survive. I've been on enough adventures with folks who were not mentally fit for demanding situations and I don't ever do that any more. I don't go on adventures that will almost surely be very demanding with people I don't know and or who I already know can't handle themselves, I'd rather stay home. Having well suited individuals around you who know what to do and how to act if things go sideways always makes for a much better and enjoyable experience even if things do end up not go according to plan. I don't know who he is, but much respect to this guy who made a tough situation look easy.
Agree totally.
Very impressive, problem noticed, stayed super clam, removed problem equipment and calmly started troubleshooting to see if repair can be done or not.
If the guy has a wing and a second stage with a swivel it's not his first picnic.
The high-pressure hose is for your pressure gauge only so the inside diameter is like a needle. If you try it, your tank will need a visual inspection after.
we do use that fist against palm signal if there is a lot of current. usualy when there is to much current for a diver, they give that signal. meaning you are swimming against a wall, staying in place instead of going forward. doesn't seem a lot of current in the video though.
Exactly, the bubbles are going straight up and when they surface it looks like they were close to shore. 🤷🏻♂️
I could watch you 2 react to anything. When woody says about his O2 blowing gus starts laughing his head off. 😂
I know right! Cmon Gus. Have some sympathy on this old man (me).
That fist to palm signal in some regions is used to signify strong current
Thanks!
1:34 is hand signal for strong current... We use that in Indonesia...
Fist on flat hand is problably for current.
Yep confirmed that’s correct.
A year ago I had a similar situation. It happened at the beginning of a dive at 16 m. It was an yoke valve and I lost almost all my air in less than a minute before my instructor geve me his octo ant shut my tank down . Soon after, we found out that there was nothing visible wrong with the o ring.
I heard from other instructors that they've witnessed the same thing. They say that the o ring on yoke valve can get displaced and that happens usually in the first minutes of a dive.
Love the videos, I haven't dived since I was a kid and watching the videos makes me wanna get into it again so much. I did a university report this year on Bernoulli's principle and I didn't think I'd see a relevant use for it so soon, so basically with fluids including air. Pressure and velocity are inversely related, so the higher the pressure the lower the velocity and vice versa. I sum it up really quick and Im far from an expert on the subject but I reckon that would explain the 55 mins, 3 mins and 13 mins situation. Im guessing the pressure straight from the o-ring would fall somewhere between the high and low pressure hoses and therefore the velocity would fall somewhere between the 2. Love the videos, If I give you guys something to look up and research Im happy lol, you guys have brought a passion back for going diving in me so thanks man.
Awesome!
DiveBusters 55 minutes cut HP hose challenge. Sacrifice two hoses and show us!
We might have to make this happen!
@@DIVETALK wrong! It must happen!
I think cutting a hose at a lower differential pressure between the tank and the exterior of the tank would take longer than at atmospheric pressure, in other words it would take longer to empty the tank the deeper you go, we are not talking about breathing from the tank here , just a pressure release time.
@@guslevesque9369 I doubt it makes a noticeable difference. The difference in tank pressure between a few hundred bar and the environment (at most 5 bar) is too large to have any slowing effect.
The LP hose getting severed will leak a tank empty marginally faster than a severed HP. The HP has marginally less flow, pay close attention to the HP port and the end of the HP hose and it’ll make sense.
Deeper depth will cause the tank to drain faster in a severed hose scenario but not for the the reason you suspect. The additional ambient pressure on the tank itself does not “squeeze the gas out faster.” The leak will speed up at a deeper depth because the 1st stage is always automatically compensating for increased ambient pressure, it does this by increasing the flow to the LP ports (it should not increase pressure much, just flow).
@Dive Talk I once had a buddy whos o-ring blew up under water.
We jumped into the sea a fair bit off the reef (after taking a compas course to the reef), as we were preparing to go in looking for manta rays. We saw them from the surface and decided to go in with them and then back towards the reef. Busy area with lots of boats, so we all went straight down to ~15ish meters.
Only 2-3 minutes into the dive I look at my buddy as theres loud noice and see bubbles flowing. Shes even more confused than the guy in this video, thinking its a speedboat going over us or something similar. When I check whats going on I see bubbles flowing from the tank valve, so I check her air gauge and offer her my octo, whish she shrugs at, until I show her how fast her gauge needle is moving. She take my octo, I turn her tank off, trying to reseat the first stage as I thought maybe it wasnt properly seated and realize the o-ring is screwed.
From the time I saw bubbles to the time I shut her tank off, maybe 2 minutes had passed and she was down to 120 bar in her tank.
Grabbing each others bcds and her breathing from my octo we held the depth (due to the busy area above), swam back to the reef, did our safety stop and was back out of the after 10 minutes. 300+ dives ago its still one of the more interesting ones. Helps that the few minutes we got was with 3 manta rays of course.
I'm no physics or diving guru, but I think Bernoulli's Principle in flow dynamics may apply here. The increase in the loss of air in the low pressure hose is further enhanced by the large internal diameter of the hose in comparison to the HP hose. Bernoulli's principle states that an increase in the speed of a fluid (applies to gas as well) occurs simultaneously with a decrease in static pressure or a decrease in the fluid's potential energy.
HP hose is very thin. It is only to transfer the pressure. I had spigot o ring failures recently. It must have been the time. when I noticed them in the water, I am usually like, I will finish the dive and sort it out at my surface interval. I am usually not worried about high pressure.
I had both failure on my right post 1st stage and my left post-low-pressure hose both at the same time. Luckily it was only at 2m deep, the beginning of a dive. It did not take very long! Maybe 3 minutes like you said. I did the live valve drills only to notice the leak did not stop until I turn all valves off. It was sad.
We can’t wait to try it. Gonna be fun.
The air in the LP hose would generally come out more slowly at a greater depth. We know the reason you use air more quickly when you are deeper is because the 2nd stage supplies you air at the ambient pressure. So when you are deeper you draw air out at a higher pressure. But the pressure internal to the LP hose is regulated only by the 1st stage (100 -150 PSI depending on your regulator model). So in that case the flow out will be determined only on the pressure differential between ambient and the LP supply pressure. So if you are deeper, that differential will be smaller. Some higher end regulators will increase the LP supply pressure as you descend in order to compensate for the decreased pressure differential at depth. So results will vary.
I guess there’s only one way to find out for sure
The tank valve has a 1st stage that drops the low pressure hose to 125 to 150 psi., before it reaches the regulator. So at 100 ft.(4 bar), roughly 60 psi, the open low pressure hose into 100 ft. deep water has an effective pressure of 65 to 90 psi. I'm guessing with the hose cut, it would free flow about 5 minutes and 23 seconds.
We’ll find out soon
Man, I hope I could react to that situation half as good as he does! Shows how much a diver can benefit from experience and training.
He was fantastic.
14:18 it's a bit late but i don't think there would be a big difference because the reason you breathe more air the deeper you go is because of the second stage hence if you cut it before the second stage it would empty at the same rate as the pressure the first stage could provide which is fixed.
On the LP hose failure at depth.
Your low pressure hose is still a higher pressure than your surrounding environment.
So the depth won’t decrease the total bleed time of your cylinder.
Been here since 500 subscribers my man Gus and Woody going to blow up soon!
We appreciate you a lot!
got here shortly after you, around 1.2k subs or so, I swear in a week they quintupled it!
Gus and Woody are just super entertaining!
AT least one diver had a A-Yoke first stage, and those are pretty prone to blow an o-ring. Since he could turn the valve off and the leak stops means it was not a tank neck blown o-ring The description says something about 200bar, which increases my thoughts that it was a A-Yoke first stage
I moved to DIN valves/regulators to avoid this kind of scenario
John
Maybe you have seen or already know this but I believe they have done this test by lake hickory scuba and there are 2 tests to I remember correctly. Love watching you guys always entertaining and good info to talk about.
To add some info:
In the description (in french) it is said that it was at the beginning of the dive (might explain no stop) and that it was from the LP hose to the second stage.
It looks like loose part in the first stage to me (sometime happen in the part receiving air from the tank) but it doesn't look like the valve. Don't you think he could have done some valve fluttering to improve his situation if the problem is after the valve ?
Still, he looks very calm and managed to get out of water with everybody.
Good info thanks.
Simply amazing how calm he was..😮😮
I believe the hand signal at 1:37 means current. I've used it a few times but I'm not sure if that's pretty international (I'm from Spain btw). It seems that the guy is telling where the boat is and that they have to swim a bit because they drifted with the current.
Yep confirmed that it does.
We use it like that also. It means strong current / we need to fight the current. I'm based in Belgium.
My regulator mouth piece froze up @ 98ft. I was with 10 people including an instructor at Dutch Springs PA in the middle of winter. Water temps low, don't remember how low. One second, I was checking out this big truck, then suddenly air started pouring out my mouthpiece and I accidentally hit my mask and they flooded. super scary. I honestly thought I was done for. But the instructor quickly grabbed my bcd by my chest, took my hand and placed a regulator in it. I take a breadth of the regulator and somehow water snuck in, I started choking but I forced myself to cough in the regulator and eventually continue breathing. I could feel we started to ascend(remember my facemask was full of water.). On the ascent I finally cleared my mask and started to feel much better. I'm just glad I was with a good instructor and glad I didn't panic(I mean "apparently panic", cause I for dam sure was panicking but only in my head).. I read later this can happen but I was unaware before the dive. Now I know why the instructor carried an extra pony tank with him on the dive..
@@TH-camWatcher29 in Europe we use 2 1st stages with a 2nd stage on either in the colder months. These 2 1st stages would be connected to a K- or H- valve on a single cylinder. Same principle when diving Sidemount or Twinsets, you have redundancy. Also, the 1st and 2nd stages would be designed for cold water. This way, a pony would be obsolete
If you haven't already, would love your reaction on this:
th-cam.com/video/v5oUxJX1Uqo/w-d-xo.html
Does the fact that the structure is man made and being explored by a professional free diver change your thoughts on things like lights, guide lines, etc.?
Will do.
just comparing basic pressures, i think the time to empty a tank with a LP hose cut at 10ft and at 100ft would be almost the same.
at 10ft you have 1.3atm or about ~20psi, at 100ft you have about 4atm or ~60psi, either of those compared to 3000 psi in the tank is basically nothing, so the air will escape at almost the same speed at both of those depths. i might be overlooking something though.
Speed to empty the tank depends on delta P between the tank and ambient pressure. So the deeper the slower.
You can imagine that at 230 meters the cylinder doesn’t even leak.
1:20 you can see something white floating behind his head above his back (the guy that gives the signs). It’s maybe supposed to be floating like that but I don’t think I have ever seen that before.
And when he quickly turns around, it looks to me like, he might have touched the string between himself and that white floating thing, and maybe it got pulled out of whatever it was attached to on him??
Prime example of keeping your cool. Great lesson.
I have had my O ring pop at 30 ft during a drift dive. I thought a boat started its engine over me. I took my buddy's Octo and did just like that guy, shut my tank, slowly got to the surface. Reset the O ring, then we went back down to finish the dive. I do hope you guys do the test. But maybe just leave the ports without plugs and open the tanks at 100 feet, instead of cutting the hose.
Love Gus and Woody. Their passion for diving is so captivating. I can never wait for the next upload. Thank you for the hard work guys!
More to come!
Staying calm helps one address issues. Don't seem to be too deep either so not as stressful as needing a long time to decompress.
@1:41 the hand sign is for Danger: high current
I saw this in similan islands & red sea
Yep that is correct. This has now been confirmed.
for us who dive open water the plan is to always get the explosive off your back ... hold it at a distance if it does go ( boom ) the concussion will not blow out your ear drums if it was not the first stage ... remember sound travels 7x faster underwater and so does concussive force...
if you were to cut LP hose on a balanced reg, air will come out the same at 10ft as at 100ft, since the reg will compensate for depth to always deliver 150psi. if it's an unbalanced reg, air will come out slightly slower at 100ft because it'll be fighting the ambient pressure, so instead of 3 minutes, maybe it will take 4-5.
I'm just thinking through what to do if that happened solo at 70ft. In my dive-class, we did something similar in my dive-class breathing from the regulator while it wasn't in our mouths, while in a pool at 10ft. So maybe you could remove the BCD, close the valve partially, and then breathe the bubble-stream. You're still losing air fast, but could potentially have enough to deco.
Good thought. Perhaps.
I had an O-ring failure on first stage just before submerge. It took like ~5-7 sec to react and close valve, so that "cost" around 10% of full tank.
Which tank valves fail more often?
DIN or Yoke valves?
That dude is the definition of zen.
I really like how that came together about the HP and LP valves. Because I thought the same thing as Woody but once I saw the valve openings it made total sense.
Yep. But can’t wait to try the experiment ourselves.
@@DIVETALK i literally can't wait to see your results.
I would very much love to watch videos where these two test equipment failures and how long befor the tank empties at different depths etc. Also the person in this video was so calm. Much respect to them for not shitting themselves and going full panic mode
Such a great video! I'm a newer diver, and these videos are incredibly helpful (and entertaining)! I learn so much each time I watch your content. Keep the awesome videos coming!!!
Awesome. Thanks so much for the support!
Sounds like an interesting test. If you have a balanced first stage it will adjust to the surrounding pressure so the breathing resistance (mediate pressure) is the same almost as at the surface. So it will probably go faster than at 10 ft at 40 ft but I don’t believe you will have that big change. The flow ought to be almost the same. Hose haven’t changed the mediate pressure is the same. For most regulators around 9-10 bar. So why should it go so much faster?
We are gonna cut the hoses and see. Will be fun also!
Thank you for the video.
Flow rate is a function of supply pressure, and orifice (opening) size.
The 55 minutes for a high pressure line would be at any depth. The high pressure isn't modified by the regulator.
The 1st stage intermediate pressure is affected by depth. At 99 fsw your intermediate pressure is 58.8 psi greater than at the surface. Your going to lose gas faster at depth. Whether you are losing gas because of breathing or a failed low pressure hose it goes faster at depth.
Thanks for the comment. We can’t wait to test this.
Another great video. Makes you think about how it all works. Counter intuitive at first glance, but so logical when you really think about it.
Yep agree.
I love watching Dive Talk. That will be as close as I get to Cave diving. I get nervous in my bathtub.
Ive had this happen twice with the Orings blowing on hired tanks and it goes off with a bang, both times my buddy was close and heard it then we were able to do a slow/safety stop accent ( I always double check the Oring now ) But if the hose fails at the SPG or 2nd stage is it possible to kink the hose off? Maybe something you guys could try if you're doing the cut hose thing. Like what you do. Cheers.
I've seen the fist against palm sign used to signal strong current.
Yep and that’s confirmed now.
9:02 We'd love to see the result of the test. I think this is an interesting knowledge for divers. Please try also to low pressure hoses :D
Will do.
What pressure is there in a low pressure hose and what does it depend on? I thought there was intermediate pressure and the second stage adjusts to ambiant pressure. So the pressure in the low pressure doesnt really depend on environmental pressure but is around 8 bar. That would suggest that the time you have doesnt really change.
Good input. We shall see.
I'm not a diver, but been binge watching your videos the whole day! Super interesting! 👌🇧🇷
Thanks for the comment and the support.
The LP hose is always at roughly 100psi. So if you are at 3atm, the flow will be much higher, so you loose air faster.
You will loose gas faster if the whole reg is off.
No need to cut the hose. Just take down a wrench, depressurize, pull the spg off (don't loose the spindle). For the lp side, just hold open the bcd inflate and vent at the same time.
We just wanna experience the cut! Lol
@@DIVETALK Hard to argue with that! Be sure to keep your hands clear of the cut on the high pressure side, and use ear pro if you do it on the surface. Looking forward tonthe video!
It's gotta be an O-ring but I can't imagine how it would rupture like that? Props to the diver, very cool-headed. I think you're right, at 100ft the air would be gone in under a minute.
Actually at 100 it will likely go slower due to the ambient pressure increase.
@@DIVETALK really? I'm having a tough time wrapping my head around this one. I would've thought it would be faster under pressure. Good job I haven't dived in years. I think I need to brush up on my Boyle's Law! lol Thanks for the reply. Enjoying your videos. Cheers!
This might be a dumb question, but couldn’t you fit more gas into a tank if you filled it in a pressurized environment? Or would it just rupture when brought back to normal atmosphere before being used? (I’m obviously not a diver, just fascinated by these videos)
The inside of the tank is 3000psi at max pressure, so you'd have to get seriously deep to make much of a difference.
The pressure differential from the regulated lp hose to the water should decrease the further you go down, thats at least what i think. So at the same time the rate of flow should decrease. As far as i know the first stage outputs basically a static pressure of about 140 psi to the lp hose, which only fluctuates due to load(breathing, bcd inflation, etc). I might be wrong here.
Yep agree
I think that you would be surprised at lower depths that it may not come out x atmospheres faster. Because the water pressure is so much higher, and since the tank is no longer a rigid closed body that has its own pressure environment (the water can now directly push on the air and affect the pressure), I think that even though MORE air might be contained in each bubble of air, the rate at which these bubbles want to escape will be reduced. So it would be very interesting to see, and to see which force overcomes the other. I suspect it will come out still at a faster rate, but definitely not scale linearly (i.e. 2x atmosphere = 2x faster or y=a*x). It may be more inverse quadratic, i.e. y=a*sqrt(x)
You can alternatively think about it like this: The air coming out has to work x times more hard to get out vs. the external pressure
Exactly what I was thinking
I think the LP hose at 100 feet would come out slower than the surface because it's not going through the depth compensation of the second stage, hence the gas would be fighting the water pressure at depth.
Don't think of slow vs fast, think of volume or flow
High pressure = low flow
Low pressure = high flow
Learned that during my rescue diver course 😁