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    Public Health Warning

    This is a discussion on Public Health Warning within the Everyday Life forums, part of the Community channel category; Ok this one is unusual for me, but one which many people who like me are qualified divers will be ...

    1. #1
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      Public Health Warning

      Ok this one is unusual for me, but one which many people who like me are qualified divers will be horrified of.

      There are some new products on the market this year. Two of them use a small (0.5ltr) cylinder or 'tank' and the other a portable pump that floats on the surface.

      Please don't use them.

      DIVERS CONDEMN COMPRESSED AIR KITS AS DEATHTRAPS - DIVE Magazine

      New Diving Offer a Deathtrap in the Making! - We Dive Too

      If you see anyone using them, either advise them about how dangerous they are or walk away.

      I have already contacted the ASA but they aren't interested as the products aren't made in the UK.

      There is a similar product which shouldn't be confused with them called 'Spare Air'. This product is specifically marketed at divers, for divers. It's an emergency bail-out option for if you run out of gas. Personally I prefer a 3ltr Pony cylinder.

      So what is so dangerous about them?

      These products are being marketed at non-divers. Whilst the instructions might give some indication of what you can do, they are no substitute for a diving course.

      One is being described as an Oxygen tank. Let's blow that myth out of the water, it contains air. Breathing pure Oxygen underwater can be lethal below a specific shallow depth.

      It is also being suggested that you can dive to a depth of 20m with one of these.

      Ok yes I do dive to 20m with air in my cylinder. However that cylinder has a capacity of 15 litres. I actually have two 15litr cylinders and dive with one at a time. Others have 10 ltr or 12 ltr cylinders, but none would dive with a Żltr cylinder. There simply isn't enough air in the small cylinder, you'll run out, panic, bolt for the surface, cause a Pulmonary barotrauma (that's a burst lung to any non-medical people) and die.

      Another issue is depth. These cylinders come with no depth gauge. Whilst they might suggest that a non-diver keep to 3-5m, how will you know how deep you are?

      Personally I have a diving watch which will tells me how deep I am and for how long, as well as a dive computer which tells me the depth, time and how long I can stay there for without going into mandatory decompression. The dive computer and watch do a little more, but that's for another day. Basically you're not going to get into a mandatory decompression dive with one of the Żltr cylinders as you'll run out of air before then.

      Another issue is getting the small tank filled up. There is a choice of a foot or hand pump. The pumps are supplied with a filter and a recommended usage pattern, but unless you have any idea about the dangers of breathing compressed gas underwater, you'll not appreciate the importance of getting this right.

      Basically if the air in the tank is damp, then it will corrode very quickly. How quick? In the right conditions about a couple of days.

      I'm don't know the story behind the picture below, but I have a series of similar pictures of cylinders which have exploded. One was perfectly alright a matter of days earlier. Seawater had been allowed to get in and it corroded on the inside enough so that 3 days later it exploded like this when it was refilled. It could have killed the person filling it, but he was lucky an wasn't harmed. The filling station was out of action for a while though.


      An exploded Pony Cylinder

      Just image what something like that would do to your foot or torso if you were filling one of the Żltr tanks.

      In case you are wondering dive cylinders must be tested periodically. Currently in the UK this is every 2 years. Legally the Żltr ones don't need to be, but anyone who has one would be foolish not to.

      One tested you get a certificate and the cylinder is stamped on the shoulder. When you next get it filled someone will check the details. If it's out of test, they won't fill it up.

      Of course since these new products are being sold with their own foot pump or hand pump, you wouldn't need to know this, even if the instructions recommend it. Who is going to check?

      So what should you do?

      Don't buy one. Don't use one. Avoid them.

      *** Rant over ***


      If you want to learn to dive there are many good dive schools/centres and clubs around the UK. You will need to complete a medical form. If there are any questions then you'll need to speak to a medical referee.

      If you want to learn on holiday, again there are many dive schools/centres, then please do think about it. Some will offer an on-line course for the theory. This can be completed before you go on holiday. Once you arrive you show the paperwork to show what you've completed and can get on with the shallow water, then open water sections.

      The list below is of some of the different clubs (UK based) and dive organisations which operation shops or centres both in the UK and abroad. Each has their own set of regulations and methods to monitor everyone within their organisation. These rules are designed to keep you safe when you are learning. Occasionally there may be a rouge instructor or centre, so please do look them over first to see what the equipment looks like, what the people are like and where any training is done.

      Ok, looking at the training site might be a little difficult in many cases as it might b a local pool or a quarry a couple of hours away, but you can ask questions.

      BSAC (Britih Sub-Aqua Club) : https://www.bsac.com/findit.asp

      SSAC (Scot SAC or Scottish Sub-Aqua Club) : Branches Finder | Scottish Sub Aqua Club

      SAA (Sub-Aqua Association) : Home

      PADI (Professional Association of Diving Instructors) : PADI Dive Shop Locator

      SSI (Scuba Schools International) : https://my.divessi.com/dc_locator

      NAUI (National Association of Underwater Instructors) : https://www.naui.org/locate-dive-centers/

      IANTD (International Association of Nitrox and Technical Divers) : IANTD UK - Technical Diver Training

      SDI (Scuba Diving International) and TDI (Technical Diving International) : https://www.tdisdi.com/search/

      If you do learn, please feel free to post some pictures.

      Public Health Warning-p5010070-800.jpgPublic Health Warning-g0021058.jpgPublic Health Warning-g0032651-twk-sign-800.jpgPublic Health Warning-vs170411-001-sign.jpgPublic Health Warning-vs170414-007-sign.jpgPublic Health Warning-g0040857-sign.jpgPublic Health Warning-g0020793-sign.jpg
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    4. #2
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      Re: Public Health Warning

      While I would completely trust Scubbie's judgement as to the danger of these compressed air kits I can't help but think that the importer has missed a marketing opportunity.

      With all the hysteria following the fire at Grenfell Tower there appears to be very little that the residents of similar blocks can do (other than moving) to mitigate the fire risk. Small cylinders of breathable compressed air used to provide positive pressure within a full face mask or hood could prevent panic while enabling residents to safely evacuate through a smoke filled core stairwell before the heat of a fire in external cladding becomes dangerous to them.

    5. #3
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      Re: Public Health Warning

      The idea is a nice one seawright, but it has some important things that would need to be addressed. Sorry for the long reply, but there are some important safety issues to describe.


      Breathing Apparatus is available and is used in places such as server rooms or in a mainframe environment. In these environments when a fire occurs a gas such as Argon is released to put out the fire. Argon does not support life (only Oxygen supports human life). The breathing apparatus can then be put on.

      I'm not sure if there is any training provided as I've never worked in such an environment. I would hope that there is as people tend to do the strangest things when there is a fire happening and it would be good to know what to do.

      The cylinders used are typically 3 litre. The same size as what I'd use as a pony cylinder for diving. Some people who are into air rifle shooting or paintball shooting will have a 300 Bar 3ltr cylinder for refilling their compressed air guns.

      They are readily available in the right places and have a specific specification. They are filled with compressed air up to either 232 Bar or 300 bar. The air should last long enough to get you out of a server room or mainframe room, even go back to recover a colleague if required.

      A full face mask is provided and positive air pressure is feed into the mask to keep any Argon and smoke out. The Argon should put out any fire as there would be no Oxygen left in the room, so fighting it isn't required.

      How many would you have in a block of flats?

      It's a bit like the emergency oxygen masks in a plane I guess, you should have enough so that there is at least one for each resident and a number of guests. However, as you'll see below, having any unused cylinders can present a real danger.

      So what is the drawback with such an idea?

      Ok forget Argon in a tower block. I don't think that would be very popular as anyone who doesn't reach a breathing apparatus quick enough wouldn't be able to breath. There will also be children and babies. You'd need special apparatus for each due to the size of their faces.

      Note: Argon is known to be bad for the Ozone. There are other gases available and the effect on a fire would be the same.

      People will need to be trained to use them. A valve will need to be turned on and the mask fitted securely over your head Not difficult when you know what to do, but things are different when you're in a panic.

      I'm not sure if those with beards would fair well with such a mask, which will be an issue for some people.

      Over a prolonged period of time the equipment will need to be maintained. With Scuba gear the regulator/s need to be serviced annually or bi-annually, depending on usage. For some it might be a lot more frequently. With breathing apparatus the mask and regulator will need a service. I would imaging once every 2 years as a minimum as O-Rings can degrade.

      The cylinder would need a full hydraulic test once every 5 years, but I would prefer the air to be changed at least once a year. If there is an slight corrosion in the cylinder it will consume the oxygen. There are cases of divers who have had cylinders stored for a long time, who have gone to use them without thinking. They didn't come back to tell us about it as the oxygen was too low.

      Another important issue with any cylinder which contains compressed gas is heat. I've mentioned the pressures above, 232 Bar or 300 Bar. To put this into context your car tyres are filled to around 2.2 Bar. A van might be 3-3.5 Bar. That means that those 3 ltr cylinders have 100 times the pressure of a car tyre. The video below illustrate what can happen quite clearly I believe...



      There is a very good reason why firefighters don't go anywhere near a fire when there are compressed gas cylinders present. When exposed to heat the metal cylinder walls will become weakened, as will the valve on top. The gas will want to expand, increasing the pressure above what is safe. t will want to go somewhere. If any breathing apparatus is left behind because they aren't needed, then they represent a real danger for the firefighters.

      The image below is of a aluminium cylinder made from a particular allow which is no longer in use. The issue was that even though it would pass the test (visual or hydraulic) but just explode with no warning when filled to the working pressure of 200 Bar. I believe that they stopped using this alloy in 1988.



      With issue of a potential fire in mind I had wondered where a qualified diver might keep his or her kit if they lived in such a block of flats. I would suggest that it might be prudent to store them elsewhere. Perhaps in a rented garage. There may even be something to this effect mentioned in any lease.

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      Re: Public Health Warning

      I would have thought that the danger to firefighters from exploding cylinders would be greater at a caravan park or marina where LPG cylinders are in use. While the pressure is not as high the contents are highly inflammable.

      Landlords should ensure that their tenants are not at risk and water sprinklers to cool the fire would be preferable to smothering with inert gas but where an individual tenant feels unsafe and has been unable obtain suitable reassurance what can they do?

      Fire extinguishers and fire blankets would be useful to prevent a fire within an occupied apartment from getting out of control but what about a fire in another flat or in a communal space? Moving would probably be the best option but where this is not practicable what other options are there?

      Having a rope to leave by a window might be a good idea but abseiling from the twentieth floor with the possibility of a fire directly below wouldn't fill me with confidence. The lifts should not be used which only leaves the stairway of which there is probably only one.

      A wet towel may help but this is only a filter which might help with removing the particulate elements of smoke but it won't make up for lack of oxygen or remove the toxic gasses generated by burning plastics. Some form of BA would appear to be the only viable option. A hood may be better than a face mask for small children or where facial hair prevents a good face seal.

    7. #5
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      Re: Public Health Warning

      Yes firefighters do have to treat LPG cylinders with a high degree of caution. Generally it involves dousing them with a lot of water to cool them down , but it can take a few days before they'll move them.

      Yes sprinklers are certainly a good idea, but there is an issue with the weight of the water.

      I don't know how much would be needed for a tower block as large as Grenfell Tower. An extra ton or two on top of the concrete building of water might sound nice, but is it something that structurally the building can handle?

      Fire extinguishers would never have been enough to handle that fire. Thousands of gallons were used to quench the fire.

      Fire blankets can be used to cover a small fire or protect a person as they leave the scene of a fire. Advice was being given at Grenfell Towers to use a towel drenched in water to cover any gaps in the doors. I was under the impression that some fire doors expanded to do the same.

      There was one person who tied some blankets together in order to escape. I don't know how successful it was. Ropes again sound good, but they can be dangerous. I als can't imagine that a 74 year old lady would relish the idea, or a mother with young children.

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      Re: Public Health Warning

      A couple of points:

      1. Fire doors don't expand but they usually have a strip of material around the outside which, when subjected to high temperature, will expand and seal the gap between the door and its surround (an intumescent strip); if the door is opened after the strip expands, however, the seal is broken and doesn't reform

      2. The toxicity of the gases produced by burning plastics and foam is largely irrelevant; what matters is that the smoke is at a very high temperature and, when it mixes with fresh air, continues to burn; it is this that kills

      3 Some years ago I investigated a fire involving a gas cyliner (oxygen) in a shed; when the cylinder became too hot, the metal weakened and the gas pressure increased until it exploded from the pressure of the gas inside, flattened out and flew over a house, landing in the road the other side.
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      Re: Public Health Warning

      Quote Originally Posted by Scubbie View Post
      Yes sprinklers are certainly a good idea, but there is an issue with the weight of the water.

      I don't know how much would be needed for a tower block as large as Grenfell Tower. An extra ton or two on top of the concrete building of water might sound nice, but is it something that structurally the building can handle.
      Assuming a mains water pressure of 4 bar, this would only be sufficient to provide a minimum domestic water pressure of 1 bar 30 metres above street level therefore in tower blocks with the top floor above this level a booster pump would be required either to pressurise the water system or fill a covered roof tank which would provide the required head of water.

      Where a roof tank is available this could double as a supply for sprinklers. The amount of water required would be much less than that used by the fire brigade in fighting the fire at Grenfell Tower as it would be applied to the seat of the fire as soon as the temperature rises sufficiently to burst a quartzoid bulb so the fire would quickly be brought under control.

      Even a single fire extinguisher may have been enough to prevent this disaster if the occupant had been alerted to the fire early enough and removed the plug providing power to the effected fridge freezer before tackling the fire.

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      Re: Public Health Warning

      Perhaps if the same EU regulations that apply to their flag also applied to building cladding then the Grenfell Tower disaster may have been a none-event.


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      Re: Public Health Warning

      Sure you don't need as much water for a sprinkler system as the fire brigade needed, but it does need to be stored on the roof of the building.

      As for getting to the seat of the fire, in this instance the resident was present. His fridge blew up. Apparently this can happen when a certain fault is present, but it's not too common.

      The initial fire was put out, as reported by the first crew on the scene.

      What went wrong is now under criminal investigation, but it appears that the cladding wasn't the correct type. It supported the fire and spread it across the outside of the building.

      Had the sprinklers been in this man's kitchen I'm sue that the fire could have been controlled sooner. The 6 minutes it took the crew to arrive after the first call was very good, but in this instance it was sadly not enough.

      However you look at it, Grenfell Tower was a disaster waiting to happen. Complaints were made but ignored. If they were listened to, then they just weren't dealt with soon enough. Perhaps too soon, but I suspect that this will be a case or corporate manslaughter. There is bound to be a lot of finger pointing and passing the buck too.

      It would be nice to prevent such a disaster from happening again. Protecting the residents should always be uppermost in the planning for any work, but someone thought they'd got it right, when they didn't.

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      Re: Public Health Warning

      More likely someone thought they could get away with substituting cheaper materials.
      How many times are the things that are tested different to those that are actually used.

      Oh, and breathing apparatus is NOT supplied in computer rooms - at least none of the ones I've ever worked in. (the alarm goes off and you have 20 seconds to leave before the shutters come down)

      A fire in a computer tape library is impossible to extinguish since the magnetic tape supplies both the combustible material and plenty of oxygen - the magnetic surface is ferric oxide, so you have pretty much a thermite bomb builtin.
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