Demand Valves and MTV's

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What we are going to look at now is the demand oxygen valve. And it is slightly different from what you will find in most oxygen kits. Where you would find this type of system are specialist emergency ambulances, but also in the scuba diving world because what this oxygen system will allow is 100% oxygen, as much as the person wants, because the person had the mask over and they can breathe into. If they are breathing really, really fast, they will always be given 100% oxygen, and it is particularly important in a scuba diving accident because it is so important that we get as much oxygen in the system to expel as much of the nitrogen out of the system. The components of it are the main true fit mask, which goes in the front. You can get different sizes of these, and this will seal around the mouth and the nose. You can easily take it on and off, by just pulling it away and pushing it back on. This is the main regulator part here, and what this will do is if you breathe in slowly or quickly, it will just give you as much as you need. This is what you call the demand valve, this is very similar to you would on an energies gas demand valve, just for delivering Nitronox or Entonox.

This particular one is a manually triggered valve as well, so on the end here, you got a button. What you can do with that is if you were doing CPR and you are doing the breaths, you can actually just set up the mask, hold it in place, push the button, and that will force the oxygen in. It's another way of pushing air into a patient without using a bag valve mask, it's just used in some applications not that common. The piping here is white because it's rated for oxygen, and on this end, you have got the main regulator, and with this regulator here is a gauge that shows you how much oxygen is left in the cylinder. You got a continuous oxygen port on the bottom, so you can use that for a pocket mask, non-rebreather mask or nasal cannula, and you got another connection here for putting another demand valve on, and this here is just a simple screw fix, so you just literally undo that and do it up, and then you can connect to the regulator to the main demand valve. On this end, there's a knob that adjusts and it's a window here, and this particular one will go up to 25 litres a minute. And at 25 litres a minute for a continuous flow is 10 litres a minute more than most oxygen cylinders will do.

So within this type of set-up, you would have an oxygen tank using a Pin Index System. And the Pin Index System is what we see in here, so you have two pins and you have the main oxygen feed, so literally on the top of the cylinder is a section like this. And on this back here, you have got a little hole, which is where this knob just connects into. On this side, you have one hole for the oxygen and the other two holes are just locator pins. To the cylinder itself, would have this on the top and you literally pop that over the top, you just line it up correctly, and then you just tighten this up in place so that you can secure it to the cylinder. You do not need to do it too tight, just do it tight enough, but do not overtighten it because you over tighten it, that's where you can do some damage. This is a Pin Index System, and you would have to use this because you are demanding a lot more oxygen from a cylinder than a conventional medical grade oxygen cylinder can provide.