Blending Nitrox From Nitrox (PSI & Bar)

what's up guys this round again from Lake Hector Scriven marina and this is part three of our series of partial pressure blending and in this video what we're going to talk about is how we can take a particular blend say we've got some air left over or even nitrox left over from a previous dive and how we can mix that with a new blend to get whatever desired level of nitrox we want now the reason we want to do this is when it comes to partial pressure blending as we learned in the second video a lot of times we start from an empty cylinder basically we put pure o2 and an empty cylinder to a certain bar or certain pressure and then we mix standard breathing gas for 21% air in it and it mixes up and it makes whatever blend and that's a very simple process to do however we're actually wasting what gas is remaining in our cylinder by simply bleeding it off and we don't really have to waste that air or whatever mixtures left in that cylinder we can do a calculation to use what's there we can determine how much we need to mix to it to actually get a desired blend now to do this we're gonna have to look at a little chart here if you want to write this down on a piece of paper it might make it a little bit easier for you to grasp onto it as well and basically all it is just through tic-tac-toe so if you can draw a hashtag or a tic-tac-toe board that's basically all I did there you don't necessarily have to put the borders on it like I do but for me it makes the math a little bit simpler but we need to understand what is in each little section of the chart here and then we're actually going to do some calculations and I'm gonna do this both in imperial and in metric for you so whether you like the Imperial or the metric system you're actually going to see both of them so on this first column here we're going to call that the desired gas column the middle column we're going to call it the current gas column and then over here on the end we're going to call that required so the desired that's going to be the ending or starting pressure field that's how much I need or how much I want to make another dive the middle and the current gas is basically how much I have left over after a given dive and then the required gas is how much I need to add to it to give me my desire in each little section here this top one let's look at the first row first we're gonna call this the desired gas column so the desired top section is going to be desired fraction of oxygen I'm going to multiply that by my desired pressure and that's going to give me the desired PPO two that I want if I look at the current gas it's going to be the starting fo2 or the fraction of oxygen let's say I had a 32 percent cylinder and I'll breathe it down to whatever and then of course starting pressure how much I'm starting with before the blending process I'll multiply those two together that's going to give me my starting partial pressure of o2 as well and then if I look at the required gas column it's going to be the required gas of o2 is what I'm going to end with but you'll notice this one's kind of flipped so I'm gonna start down here at the bottom it's the required partial pressure of o2 that I need to get to my desired level the required pressure that I've got to add into the cylinder to get to my required level if you will and then of course they required Oh two for that particular blend so and we to go this way I'm actually going to take the required PPO to divide it by the required pressure and then get my required o2 now there's some other arithmetic here as well you'll notice I have these two subtraction marks here and that's because to get these two numbers I'm gonna have to subtract it out to get it and you'll see when we fill in the block what I mean by that once again we're going to do this both in Imperial and metric and if you want to follow along get you a piece of paper and a pencil and also get you a calculator as well and it'll make doing the math a lot easier now one thing that I will say on the calculator if we get a particular number that can be rounded up we're going to round up just to make it easier on us and we're only going to be using basically one or two decimal points over so if I say forty percent instead of saying point four zero I just say point four if I had say a point one three nine I'm gonna round that up to a point one four so just just so that you can follow along with me but let's let's start filling in a block here with a particular blend that we currently have and we'll see how we can convert it or up it or even lower two blend that we want so let's say that my starting fo2 I've got a cylinder that has 32 percent in it and I just finished that dive and I still got nine hundred and seventy two psi in the cylinder okay so at this point I can go ahead and do some of the math out here I can take 32% point three - I'm on times it by nine seventy or 972 psi and that's going to come up to 311 and oh four I'm just gonna say 311 psi so out of that cylinder of 32% nitrox that has 972 psi 311 psi of it is the 32% partial pressure of o2 that's pretty easy to understand well let's say that I want to boost that cylinder to 36% so I'm just gonna go to my desired fo tune right in 36% real simple right and I know that that cylinder is gonna hold 3,000 psi which is what I want to or that's my desired pressure so I'm gonna go ahead and write 3,000 psi here now there's some more math that I can do desired fo2 times desired pressure is gonna give me the desired Oh to that I need so I just simply take point three six so point three six all right I'm going to times that by 3,000 that's going to give me 1080 psi right now from here to get over to the required gas that simply puts how much o2 or how much gas I got to put into the cylinder I can simply do the subtraction of these two rows here so I'm gonna take my desired PPO - - my starting and that's gonna tell me how much pressure I got to add to the cylinder so I'm gonna take 1080 I'm gonna - the 311 from it being see that it comes up to 769 psi all right now I'm gonna do the exact same thing with road number two I'm gonna take 3000 I'm gonna - 972 psi from it tells me to zero to eight now the last thing I need to know is the required Oh to to put into that mix and to do that I simply take 769 following the arithmetic here I take 769 I divide that out by the 2028 so two zero two eight and that's going to come up to point three seven nine we're gonna simply call that point three eight or thirty-eight percent so in short if I had a 32% blend and I wanted to make it a 36% blend I'm gonna have to add thirty eight percent nitrox to my cylinder or more importantly if I had 972 psi and I wanted to add three thousand or I wanted to make it 3,000 psi obviously I got to add 2028 psi to it and then if we look at the mixture of oxygen or a partial pressure I'll say that in a cylinder that had 32 percent at nine hundred seventy two psi that means 311 psi of it is the o2 I would have to add 1080 psi to it alright to get the desired 769 psi needed for that blend to get it to my thirty-six percent so guys figuring this out it's very easy once again we do this to conserve the air that we still have or the blend that we still have we don't have to take the time to drain a cylinder all the way down to start the partial pressure blending process we can simply work out the math and we can do it very easily without wasting any gas in our cylinder now I did promise you that we're going to do it in the metric system as well so let me simply erase some of the numbers here and all that we're going to do is simply change it out from psi to bar so I'm gonna leave those top numbers there because I'm gonna actually start with 32 percent and I want to get my desired mix at the 36 percent so obviously we know that 38 and I'm gonna actually erase that too just to show you the math behind it we need to know how much a partial pressure to put in there as well so let's say I start with a cylinder that's 32 percent nitrox and it currently has 67 bar in it and I want to end after the partial pressure blending process I want to end with a 36% blend and of course I want 200 bar in my cylinder so I can do the exact same math that I did before simply by using the calculator here all you're going to do is take point three six point three six you're going to times it by 200 it's going to give you 72 bar you're going to take point three two you're going to times it by 67 it gives you 21 point four four now we needed to do our subtraction we're going to take 72 we're going to minus the twenty one point four four that's going to come up to fifty point six we're just going to simply or fifty point five six we're going to round that up to fifty point six we do the same thing here we're going to take two hundred we're going to minus 67 from it we're going to get 133 and then we can do our division to see what the blend is or what the blend needs to be to make that particular desired so we take fifty point six divided out by 133 it tells me there's my thirty eight percent as well exact same number we came up in with the imperial system so guys it's a very simple process if you'll draw out your hashtag or your tic-tac-toe board and understand that the first level or the first column is desired gas the middle one's current gas and of course the last ones required gas and understand what each block is being able to take nitrox of whatever blend at whatever pressure and change it to whatever blend and whatever pressure you need becomes very simple once again we use this guys so that we don't have to drain the cylinder first to start the partial pressure blending process guys if you've got any questions on this please put it down in the comment section below I really truly appreciate you watching this series as well if you want to see more technical related videos like this drop me a comment down below on a particular video that you would like for to make for you as well because if you liked this video smash that like button for me and definitely share it as well and if you've not watched the previous videos in series check out in the description below I'll have those linked down there as well just simply click on that and you can watch through the entire series of partial pressure blending because I really hope you enjoyed these videos as always guys make sure you follow us on Instagram and Twitter like us on Facebook pin us on Pinterest subscribe to us here on YouTube and as always guys we appreciate your business guys we really appreciate you watching our videos if you liked it make sure to give us a big thumbs up if you're not a subscriber simply hit that subscribe button for us and make sure you hit the little bell to turn on all notifications if you want to see some other cool videos make sure to click these links here they can be scuba tips that can be diving videos search-and-recovery videos or gear reviews once again guys we really appreciate it

Channel: LakeHickoryScuba

Views: 2,179

Rating: 4.9540229 out of 5

Keywords: Blending Nitrox From Nitrox (PSI & Bar), How To Blend Nitrox, How To Make Nitrox, Partial Pressure Blending Nitrox, Lake Hickory Scuba Center And Marina, Instructor Bryan Stafford, Scuba Schools International, SSI Nitrox, Padi Nitrox, TDI Nitrox, Technical Diving, Trimix Diving

Id: mWrtxyFKF-g

Length: 11min 53sec (713 seconds)

Published: Thu Jan 31 2019