Hot fills make the risk of tank explosion much greater, while when wet filling the chances drop dramaticaly, plus the fact, that if an explosion does ocure, the water will reduce the size of it (shock passes from medium to medium losses effeiciency).
Tank fills- Wet or Dry?
- Thread starter Waterlover
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While I'll agree that slow, cool fills are the way to go, and hot fills place unnecessary stress on the tanks and do potentially shorten the tanks service life, I don't agree that a water bath will protect oneself if the tank explodes while being filled.
When that steel tank exploded during filling at the Sebastian, FL Dive Center, the tank was in a water bath that had 8 inch thick cement walls. When the tank let loose, the resulting explosion took out an entire wall spreading debrit out onto US 1. The owner died of massive head and chest injuries.
So let's put to rest the notion that water baths will protect the person filling the tank if the tank explodes.
Just my 2 cents
MASS-Diver
Contributor
The dive shop I fill at uses a water bath, I always get very good fills (I have a 120hps), although they have a large compessor, they will still often take 5-10minutes to slowly fill my tank, which I apprecaite. Bad fills can be a real downer. I agree though, that a water bath would do little to contain the damage in the case of tank blowing.
I'll be eager to see others views on this as I have always been curious about the dry vs wet issue.
I'll be eager to see others views on this as I have always been curious about the dry vs wet issue.
uses their compressor to fill a bank of T-cylinders in the AM. Thus giving time for the heat to disapate. Then they fill from this bank all day, and the compressor just sits. While there is some adiabatic heating, there is no heat from compressing to get in the way. Still, they fill my tanks slowly, and I can not ever remember getting a bad dry fill from them.
As for water "absorbing" the blow... it's noncompressible and becomes a missile like anything else around an exploding tank. Do a belly flop off of the high dive if you really want to see how hard water is.
As for water "absorbing" the blow... it's noncompressible and becomes a missile like anything else around an exploding tank. Do a belly flop off of the high dive if you really want to see how hard water is.
My LDS also fills from a bank, dry, but I've noticed that fresh tank fills are still hot, and tend to drop 300 PSI. They also do fast fills, and if the "3AL" on the tanks is any indication of the age and alloy, I'm glad that I got my curiousity about tank filling over and stay in the other room while they do their fills.
OTOH, http://www.scubapointpk.com/info.htm filled my tank SLOWLY in water bath... consistant fills to 3k psi that didn't shrink when I hit the water.
Because water is infinitely malleable, and would spread in a sphere from the site of the tank (losing energy and density according to some square law), you would be unlikely to experience penetration trauma from the water jacket of tank fill station. I don't know the particulars of the injuries of the LDS owner/worker who was killed, but it was pretty likely to be either pieces of the tank that escaped the jacketing, or pieces of the jacketing holding the water in which the tank was immersed.
IS there a tank containment system that is proven to contain a full tank explosion that is suitable for fills? Just curious.
OTOH, http://www.scubapointpk.com/info.htm filled my tank SLOWLY in water bath... consistant fills to 3k psi that didn't shrink when I hit the water.
Because water is infinitely malleable, and would spread in a sphere from the site of the tank (losing energy and density according to some square law), you would be unlikely to experience penetration trauma from the water jacket of tank fill station. I don't know the particulars of the injuries of the LDS owner/worker who was killed, but it was pretty likely to be either pieces of the tank that escaped the jacketing, or pieces of the jacketing holding the water in which the tank was immersed.
IS there a tank containment system that is proven to contain a full tank explosion that is suitable for fills? Just curious.
My personal compressors are only 4-5 cfm but the SCUBA tanks still heat up significantly and have to be topped off later. When aboard a boat I dip the hot tanks in seawater and put them back in the filling line; otherwise, they lose 300 psi. A lot of work but I get tired of hearing the whispers.
Otherwise, this doesn't cause a technical problem of any kind. The yoke type valves are easy to blow clear and everything moves along. Also, this is where the tank boot becomes useful, a standing tank is easier to manage. I install boots on my steels prior to leaving on a trip.
Otherwise, this doesn't cause a technical problem of any kind. The yoke type valves are easy to blow clear and everything moves along. Also, this is where the tank boot becomes useful, a standing tank is easier to manage. I install boots on my steels prior to leaving on a trip.
You are right, offcourse.
But still-two things-
1-water DOES reduce the explosion, it's a fact. But when a tank explodes the way it did in this case, nothing can help. But not all tank bursts are this bad. Usualy it's just the tap flying to the sky (and anyone that works on boats with "hot fills" knows how scary it is. Or the top bursting. on a case of a side explosion... well- Its way more seriouse that a grenade.
2-The water bath will cignifically reduce the chancces for all of this to happen in the first place, and also it will probobly make a case that might have ended with an explosion, just with a burst or so on.
scubeedoo
Registered
The local dive shop fills dry and fast, and I end up losing 300-400 psi when it cools. The dive magazines claim that doing it wet is a bad idea, this was in some Rodales issue some time ago. I can't remember why it was bad. All I know is when I get my tanks filled in Tobermory where it is done wet, I get a little over 3000 psi. In Essex, 2500-2600 psi.
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