Scalding hot tanks

[TomZ]

So I waited today while the dive shop filled my tanks. I was driven there by a friend, who commented he had not seen tanks filled before out of the water. I said, wow, these are hot. Another diver had just walked out of the store after his first visit, and commented there was no way they filled them without being in the water. He then felt the tank, and said, yup, filled out of the water. He said he would not have his tanks filled here.

Being newer to this sport/occupation I was unsure, as I had never waited before for my tanks while being filled. Is it normal to give them back very very hot? Is it normal to fill them without cooling in water?

well, she said she filled it to 3300PSI hot temp, we will see what I have left later. Last time I left them I had 3600PSI cold. If I only have 3000 this time I will not be as happy.

Your right, it was dumb of me. I have two AL80's I use for bottom cleaning.

I do use almost all the air. When I am 10' below the surface, running out of air is not a big deal

Its curious to read about all the viewpoints. Have there been no tests done on this subject?

As far as safety I would say a tank in water is more safe. Water may not compress much, but just like lead plates, it can slow down shrapnel.
I know this because I am a physical chemist, not because I am an old time diver

My regulator will be hard to breathe from when the tank is almost out, right? If that is the case, it will be easy to have something left in the tank. ran the last one to 300psi.

Your first post was a valid question.

Your second post indicates a lack of knowledge, which is addressed in subsequent responses, including:
PSI-PCI - Filling Cylinders In Water - Time to Review, which is from the agency that trains the scuba industry in the proper techniques of cylinder filling and maintenance.

Your third post goes against the majority of the advice given to you, and contradicts the quoted article. You defend your theory on your knowledge as a physical chemist, not a knowledgeable diver.

Your fourth post (again) speaks to your lack of knowledge about safe diving diving practices.

Defending your original (unsafe) concepts in the face of factual information to the contrary doesn't seem to be the most efficient way to learn. Good luck.

 

[luscioman]

One of my LDS uses a water bath when filling. On a recent fill they had the tank standing up and not submerged and it was almost filled. They laid the tank down and moved it around to let water flow over it and it dropped it 150psi in about 15 seconds.

 

[MrChen]

Thanks for the follow up guys.

 

[scoobert]

Your fourth post (again) speaks to your lack of knowledge about safe diving diving practices.

Defending your original (unsafe) concepts in the face of factual information to the contrary doesn't seem to be the most efficient way to learn. Good luck.

The first thing I had to disregard after my scuba class was safety. All the never dive alone, buddy system stuff went out the window, and was saved for a diving holiday. I think this has made me a bit better of a diver. There is no one to catch my mistake, or pick me up when I fall. Even after just 18 dives, I know my gear very well, and I am confident in skills most people never even master. EG I can dive in a body of water with no visibility at all. At times it is so bad I see the reflection in my goggles. I can mostly see things less then 3" in front of my face. The best visibility I have ever had while working, was 3' one day. I am not saying I am ready to cave dive, decompression dive, ECT. What I am saying I have learned a lot of advanced diving, within the first week. I think I also dive much more then the average person, at least once per week. So safety? I have enough safety, and all that I need to dive to 12-16' solo, weekly, in 0 visibility.

contradicts the quoted article. You defend your theory on your knowledge as a physical chemist, not a knowledgeable diver.

I didn't see the article. I will go read it. I stand by my "in the water theory", based solely on ballistic testing in the water.

So I read the article. I agree. If your going to fill the tank in a plastic water tub, and think your protected, you are wrong. However If you fill them in a thick wall, large tank you remove the risk. I know this dive shop has a filling rack for the tanks that lock them into itself, and is constructed of very heavy steel. So blast protection it does have. Cooling may be better served by this compartment being refrigerated while the filling is happening. With a goal of room temperature when the fill is complete.

Overall I have my answers.
A wet fill is unnecessary.
The shop fills the tanks too fast (external temp on the tank was pushing 140-160 degrees, AKA touchable, but you could not hold your hand on the tank. This can cause metal fatigue.
I will let the owner know his full-time employee is filling the tanks too quickly. I know he will care.

 

[fire_diver]

The first thing I had to disregard after my scuba class was safety.

And there's the winning post! Goodbye, good luck, and I hope you don't kill yourself. I'm done trying to help you and putting you onto the ever-growing "ignore" list.

 

[Wookie]

I don't know a single professional hull cleaner that uses cylinders. They all have surface supplied compressors rigged to supply breathing gas with a k cylinder backup. Of course, hull cleaning is commercial diving, so I hope you aren't doing it on a recreational cert. But you know all this, cause you threw safety out the window.

 

[Croomrider]

The guys up at cave country told me that filling in water was basically a "wives tale" type thing. Other shops have told me it's important to cool the tanks as has been mentioned in this thread. I'm not sure what to believe really. The shop doing the fill makes that decision, so I guess it doesn't matter much what I think. I'm unlikely to take my tanks somewhere else over the question of fill bath or no.

For me filling wet is enough of a reason to find another shop, and to pay more if I have to. Early on I had water pumped into my steel tanks. I know this to be the case, because I never ran them lower than a few hundred PSI and they still failed the next VIS, from water and rust in the tanks. I had to have them blasted. It's too easy for incompetent shop help to drop a fill whip into the water before connecting, and then force water into the tank. Also, tanks should always be burped before filling in case there is any water in the valve from rinsing or otherwise. I have learned to do this myself before taking them to the shop, because all shops don't do it. I have not had any further problem with getting water into the tanks!

Mike

 

[String]

There's debate about whether a water bath actually does ANYTHING for fill temp/pressure anyway. I see far far more fill stations not using water than those that do and its no issue. Fill slowly, allow to cool, top up. Same system. Works and effective.

Scalding hot tanks just means the shop filled them too quickly or needs to top up after cooling.

 

[DivemasterDennis]

We fill our tanks out of water as a rule, and there is nothing wrong with that, but you must fill them slowly. A hot tank is a tank that may read 3000 psi when they give it to you, but when it cools it will likely be 2500 psi or even less. Placing a tank in a water tub or tank while filling allows quicker fill, but a fill that is too quick will still be less than a full tank. Tank fillers should take a class for tecks that do that work-it was a part of my DM training and certification.
DIvemasterDennis

 

[scubafanatic]

In the Dallas/Ft. Worth area, I've only ever seen ONE dive shop use a water bath (reinforced concrete) for tank fills, which went out of business in 2006 (Tucker's Dive Shop). I actually like the water bath method, so it's a shame it's not more widespread.