billskip
Well-known member
The more pressure in the bottle the longer it will last...I guess with the pressure that pump and your strength will provide will probably only give a short usage time.
Breathing bottle
- Thread starter Bouba
- Start date
Bouba
Well-known member
I have an electric 220 v compressor onboard…but I don’t think it does much more than 6 bar…perhaps 8 bar…how long will that last underwater?
billskip
Well-known member
Quite a while if you dont breath.....
Depends on volume of bottle and of course the consumption volume and rate.
There is a formula, I cant remember it now, that will allow you to calculate the volume in the bottle at different pressure.
Portofino
Well-known member
No long enough to achieve any thing you couldn’t do holding your breath .
As I said the Fr dive shops ( suspect legally ? ) have to ck the “ date “ it was last tested before ramming in 200 bar .
If it’s out of date they refuse .Iirc it’s €40 every two yrs , they send it away for testing .Comes back stamped with a expiration date .
A simple refill is peanuts .
Flyingspanner
Active member
Yes about £1000 in the UK - but enables you to do a lot more than the single bottle style - there are also Chinese versions for less than 1/2 the price
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DavidJ
Well-known member
Remember that at 10 meters you use up twice as much air than at sea level.
This depth could be realistic, say in the Med trying to retrieve a stuck anchor. (or as was for me an overboard flagpole using a SpareAir)) Add to this diving inexperience and physical work ….you don’t have too much breathing time!
This depth could be realistic, say in the Med trying to retrieve a stuck anchor. (or as was for me an overboard flagpole using a SpareAir)) Add to this diving inexperience and physical work ….you don’t have too much breathing time!
Divemaster1
Well-known member
Presumeably the "500" refers to a size measure, so let us assume that is 1/2 liter internal volume. @ 200 BAR, that equates to 100L.
Assuming we (at rest and at surface level) exchange approx 0.5L at a rate of 12x each minute which gives us a consumption rate of 6L/Min and triple that with physical exercise to 18L/Min.
So as a result, this 1/2 liter bottle would give you 5.5 min of air at the surface (100L/18) and half of that at 10M diving depth... and if an in-experienced person run out of air and panics at that depth, then you are at serious risk of air embolism when ascending which may be life threatening...
jfm
Well-known member
We have used these for a decade as toys and would never do 10m with them. They work really well for a quick look at propellers, or goofing around underwater with GoPro or Seabob, at 2-3m depth - that kind of thing.
Bouba
Well-known member
What do you fill them with ?....and to what pressure?
jfm
Well-known member
Connect to a dive bottle, so 200bar. That gives you decent run time.
That hand pump is a joke
That hand pump is a joke
diverd
Member
Those hand pumps are often used to fill air powered rifles, and they will eventually get to 250 bar. Some are 2 stage, some 4 and they are not overly difficult to use. Its a bit of a work out but would fill that in probably 10 minutes if its a decent one. i have used them in the past and they work ok, but if you are filling anything regularly to 200 -300 bar you really need a decent scuba compressor. The 6-8 bar compressors are designed to fill low pressue high volume, things like tyres, water toys and the like. They can never fill to the pressures you need for scuba kit, and of course dont have the air filtration and purification needed. I have a 300 bar compressor, high pressure, low volume, in my workshop for filling my scuba bottles, it would fill that wee bottles in under a minute, with the correct adaptors, but when these things were released in the UK probably 20 years ago they were sold with an adaptor so they could be filled from your scuba cylinder, a known dry clean air source. If you are a trained diver and understand the hazards of compressed air under water its a small easily stored tool on a boat. I would not recommend it if untrained as they can cause all manner of injuries. I always have a basic scuba set on board, usually a 5 ltr 300 bar cylinder, so 10x times the volume of that wee thing and 1/3 more pressure, and i can get an hour plus easily as boat hull / keel cleaning depth, probably nearer 2 if not scrubbing hard. In reality these days there are far better solutions to working short term shallow water jobs like prop work, and the ones with a small cylinder, with basic regulator and BCD all built into one package would be far safer. I believe they would be £3-400 but its a useable tool and not really an emergency bail out tool.
Portofino
Well-known member
Agree even with my larger bottle on a vest + weights + regulator which easily lasts 20 mins inc physical effort prop scrubbing we or I never go greater than a public pool .My draft is irrc 1.2 M ? .
Cant comment on the pump debate as we use dive centres to top up .
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