Dive Cylinder Explodes - Sydney

[tarponchik]

Fragments of tanks or secondary projectiles are what kills people who are not right next to the tank. The shock wave dissipates a lot faster.

For example An M67 fragmentation grenade has a 6.5oz CompB bursting charge and a casualty radius of 15m (50% chance of death or serious injury), though fragments can be blown up to 230 meters. A cardboard MK3A2 concussion grenade has a bursting charge of 8oz TNT (roughly equiv) and has a casualty radius of 2 meters, though the few metal pieces can be thrown 200 meters or so. So if you take out the threat of metal fragments the danger is vastly reduced.

Unfortunately scuba tanks are made of metal.

Hand grenades are designed to produce multiple projectiles, spreading more or less evenly. Scuba tanks, on the other hand, explode differently, as Wookie mentioned before. I haven't seen any myself but here is a photo I found proving the point:

In this case, there were probably just two pieces flying, the large chunk in the guy's hand and the tank valve. So chances of being hit by shrapnel in case of scuba tank explosion are probably low.

 

[BRT]

Point is the tank becomes as much a part of the explosion as the cylinder itself after absorbing the energy of the exploding cylinder. The nice thing about containment fill stations is that they direct the energy of the explosion away from the peoples.

This makes as much sense as wanting air between you and an incoming bullet rather than water. Or air between you and an incoming piece of shrapnel instead of water.

 

[redacted]

This makes as much sense as wanting air between you and an incoming bullet rather than water. Or air between you and an incoming piece of shrapnel instead of water.

How much water are you taking about? A couple inches probably will not help much. Maybe a couple feet will make the difference. So, are you saying tanks should be he!d under a couple feet of water during filling?

What could possibly go wrong with that?

 

[Patoux01]

What could possibly go wrong with that?

Dunno, don't we do that all the time, taking a tank underwater?

 

[Nikole]

Nitrox cylinder?

 

[redacted]

Dunno, don't we do that all the time, taking a tank underwater?

As long as the tank monkey keeps the fill whip dry (dries it thoroughly between fills) and keeps water out of the valve, it could work. I would have more confidence handing my 3 y/o a full glass of milk to carry to the table.

 

[NAM001]

As long as the tank monkey keeps the fill whip dry (dries it thoroughly between fills) and keeps water out of the valve, it could work. I would have more confidence handing my 3 y/o a full glass of milk to carry to the table.

You are right. the problem being that tank monkeys are not careful and end up getting a little water in the tank. When you are bulk filling , it happens. Again the no water bath is a one technique fits all remedy. Much like mothers driving the kids to school till they graduate because of an accident 1000 miles away.

 

[NAM001]

I am working on getting a spray hose collar for the tanks. the sprayers like the grocery stores have at the vegetable counters. That and a towel on the tank. It sure removes a lot of heat. The ultimate answer is still slow fills which is not possible in a volumn business. Im using a 6 cuft compressor filling 2 tanks at once and they still get hot. eventually I will have air line in a ice water bath to cool the air before it hits the final moisture separator. That should get more water out, make filters last longer and hopefully have cooler fills.

 

[Patoux01]

The ultimate answer is still slow fills which is not possible in a volumn business.

There's also those that refuse to do that and/or cannot do it (which I found rather odd). I filled 2 s80s on a 36m3/hour (1200 cuft/hour, or 20cuft/min), starting at 30bar each, well, I could have baked an egg on them at the end... I wasn't quite happy, and contrary to what wookie suggests, my instinct tells me that if the outside of the tank stays cool-ish, the inside won't be as warm as when dry filled. I dive aluminium tanks, so except the layers of oxyde on in/outside, the rest can drain heat pretty fast without trouble I'd believe.

I'd also have prefered ending the fill at 220b instead of 240 to get ~200b. Even as an engineer, I really don't like compressed gas, especially not when going even so slightly out of the recommended range of use.

Since most of the fill stations I have available are located outside (self service), this brings me to a question, how does one fill a cylinder slowly? I don't mind waiting 15 minutes instead of 5, if it can increase (even slightly) the safety and the amount of gas I'll have available... Don't open the valve fully? Make pauses?

 

[KevinNM]

Hand grenades are designed to produce multiple projectiles, spreading more or less evenly. Scuba tanks, on the other hand, explode differently, as Wookie mentioned before. I haven't seen any myself but here is a photo I found proving the point:

In this case, there were probably just two pieces flying, the large chunk in the guy's hand and the tank valve. So chances of being hit by shrapnel in case of scuba tank explosion are probably low.

Yes, in this case. Though the valve, the fill whip, the knob on the fill whip, and any secondary fragments created when they strike something are also going to be moving at lethal velocities. And big fragments can go a very long way. Like many tens of meters.