Filling dive cylinders using a Bauer compressor?

Tezza · Post by **Tezza** » Wed Feb 22, 2012 7:49 am

G'day guys.
I've just recently ordered my first air rifle, an Air Arms SL 510 in .22, which i'm pretty bloody excited about. I've yet to buy the scuba tank etc., and have a query. I'm in the Navy, and we use Bauer compressors onboard to refill our OCCABA (Open Circuit Compressed Air Breathing Apparatus) bottles, which we wear when fighting real/pretend fires and toxic hazards. Obviously the Bauer is able to fill the bottles with breathable air, to 300 bar. Do any of you blokes know whether i'd be able to use one of the Bauer compressors to fill a diving cylinder? I know most diving cylinders are rated to 232 bar, the Bauers pressure regulator is adjustable from 200 to 300 bar. I'm no expert when it comes to bottle filling however, and the bottles we use are carbon fibre and perhaps more forgiving than an aluminium bottle, and i'm not sure of how safe it is to fill a dive cylinder using the Bauer. Any thoughts or ideas lads?
Cheers, have a good one.

Ned Kelly · Post by **Ned Kelly** » Wed Feb 22, 2012 9:23 am

G'Day Tezza,
we get our BA cylinders (steel cylinders and composite wrapped aluminium cylinders) filled by a industrial compressoer (dont know the brand) at one of the larger fire stations and provided you can connect the dive bottle using suitable adapters to it and have confidence in the pressure setting and it is filled slowly to avoid heat, it shouldn't be an issue. I would recommend filling to 10% less than the rated pressure for saftey if you have any concerns.
I'm assuming the pressurised air is dry and clean of contaminants given it's intended use, as moisture inside the bottle will eventually cause corrosion.
Also consider asking some of the dive bottle fillers what their equipment is and they may have fitting s you need and rumour has it that for a slab beer you can "acquire" just about anything in the services!
Hope this helps.
PS we regularly use 3000psi nitrogen and breathing oxygen at work servicing aircraft systems and I'm sure that if you can find the right fittings you'll be on the way.
Cheerio Ned

Yrrah · Post by **Yrrah** » Wed Feb 22, 2012 11:45 am

Tezza wrote:G'day guys.
I've just recently ordered my first air rifle, an Air Arms SL 510 in .22, which i'm pretty bloody excited about. I've yet to buy the scuba tank etc., and have a query. I'm in the Navy, and we use Bauer compressors onboard to refill our OCCABA (Open Circuit Compressed Air Breathing Apparatus) bottles, which we wear when fighting real/pretend fires and toxic hazards. Obviously the Bauer is able to fill the bottles with breathable air, to 300 bar. Do any of you blokes know whether i'd be able to use one of the Bauer compressors to fill a diving cylinder? I know most diving cylinders are rated to 232 bar, the Bauers pressure regulator is adjustable from 200 to 300 bar. I'm no expert when it comes to bottle filling however, and the bottles we use are carbon fibre and perhaps more forgiving than an aluminium bottle, and i'm not sure of how safe it is to fill a dive cylinder using the Bauer. Any thoughts or ideas lads?
Cheers, have a good one.

You should have no problems. Buy a 300 bar steel or carbon fibre (if available though costly) tank and DIN fittings. Aluminium is only to 232 bar and old ones are beginning to fold up. ... Follow Ned's advice. You can use nitrogen but do not use Pure O2. Dry filtered air is the go. ...... You have access to a great compressor, capitalize on it with a 300 bar tank to get the most fills at the rifle's maximum fill pressure. Obviously if the rifle works from 200 bar, a 200 bar tank will give progressively less than 200 bar each subsequent fill. Get the biggest 300 bar tank you can afford and can store in the space you have and can transport to and from any distant shooting venues ... Kind regards, Harry.

Tezza · Post by **Tezza** » Wed Feb 22, 2012 9:09 pm

Cheers for the info Ned and Harry, appreciate it. I reckon I might try and get myself a 300bar bottle and see how we go. For info, when we fill our carbon fibre bottles up, we usually fill them to 310bar to allow for the drop in pressure when the bottles cool. Can you do this with Steel bottles? I'm guessing there's a safety margin allowed in the rating of bottles, but does anyone here fill steel bottles in this way?

Yrrah · Post by **Yrrah** » Wed Feb 22, 2012 9:27 pm

Tezza wrote:Cheers for the info Ned and Harry, appreciate it. I reckon I might try and get myself a 300bar bottle and see how we go. For info, when we fill our carbon fibre bottles up, we usually fill them to 310bar to allow for the drop in pressure when the bottles cool. Can you do this with Steel bottles? I'm guessing there's a safety margin allowed in the rating of bottles, but does anyone here fill steel bottles in this way?

My dive shop struggles to give a full 300 bar with its compressor booster but I doubt that as a general rule any would fill beyond 300 bar rating. My shop likes to have the bottle for a period long enough to top up after cooling. The bottles are put in a water tank to act as a heat sink to reduce the problem. Generally when I go back to collect they will put the booster on again to top up that last bit. ... If some similar procedure is undertaken at your establishment I would suggest staying within the 300 bar pressure criterion. But if you can acquire a carbon fibre bottle then perhaps the protocol could be followed. I would love to have a carbon fibre bottle for the weight saving but have no information on suppliers and the price is probably beyond justification for me .......... Kind regards, Harry.

Post by **GriMo** » Wed Feb 22, 2012 9:50 pm

The water also minimizes damage if a bottle ruptures when filling. Surprising amount of heat is generated when filling

Rabbitz · Post by **Rabbitz** » Tue Feb 28, 2012 7:36 pm

A 300 bar cylinder will easily handle 20 or 50 bar overfill. It will then cool to around 300.

Every year the cylinder is tested to around 450 or 480 bar anyway. (8/5ths the working pressure, yes eight fifths).

For the number of times you will cycle the cylinder in a year you will do no harm.

I would imagine those who fill the cylinders on the ship / base would have been trained given the OH&S crap we all have to endure now, so they will give you the good oil anyway.

By the By GriMo, all the water does when anything lets go is amplify the amount of poop that ends up in your undies... There is a lot of energy in a cylinder and if one lets go even a proper blast screen will show signs of damage, so the water is really just to help cool the cylinder (and even its efficacy in that is questionable).

Tezza · Post by **Tezza** » Tue Mar 20, 2012 2:07 pm

Rabbitz wrote:A 300 bar cylinder will easily handle 20 or 50 bar overfill. It will then cool to around 300.

Every year the cylinder is tested to around 450 or 480 bar anyway. (8/5ths the working pressure, yes eight fifths).

For the number of times you will cycle the cylinder in a year you will do no harm.

I would imagine those who fill the cylinders on the ship / base would have been trained given the OH&S crap we all have to endure now, so they will give you the good oil anyway.

By the By GriMo, all the water does when anything lets go is amplify the amount of poop that ends up in your undies... There is a lot of energy in a cylinder and if one lets go even a proper blast screen will show signs of damage, so the water is really just to help cool the cylinder (and even its efficacy in that is questionable).

Cheers for the info Rabbitz. Actually, every sailor is taught to fill an OCCABA cylinder, and I can happily fill one myself, though the instruction we are given is fairly minimal considering the amount of damage a cylinder that explodes could do...........i've never really thought of it before............it makes me kinda nervous now.

stinkitup · Post by **stinkitup** » Tue Mar 20, 2012 8:21 pm

Most things "engineered" generally have a safety factor eg cranes and stuff that lift are usually rated under full tested capacity etc Even speed on our roads run at around a 15% safety margin. I would say the bottles are no different.

Ryan

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