Empty Tanks

[Scuba_Dad]

I've always been taught to never let my tank get completely empty, because of the possibility of moisture getting into it. Well, I recently got into a debate with one of my local dive shops on the topic. He wanted me to empty my nitrox tanks before getting there... I explained to him that emptying a tank wasn't in my nature. I prefer to drain it down to 100-200 lbs and let the remainder drain out after I got to the dive shop.

After I got my nitrox tanks filled, I went over to the dive shop I teach out of, and it just so happened that a customer came in, and he wanted his tank filled. When she checked the tank, it was empty. She informed the customer that she would have to do a VIP on the tank. Well, the customer got upset... accused her of trying to make extra money off of him... etc...

Now... anyone know if it's just a dive shop policy to VIP empty tanks, or is there some regulation or standard that forces a dive shop owner to VIP them?

btw... my favorite local dive shop now has nitrox, and they don't empty the tanks before filling. They calculate how much O2 is required to bring the tank up to the requested mixture. It's pretty accurate, too.

Al

 

[CD_in_Chitown]

It's a good idea to VIP any tank that is completely empty. If you suck it dry under water it's going to take on water, the fill monkey doesn't know that you just drained it for kicks.

As for the shop wanting you to drain the tank before you took it to him I'm confused. If you were just going in for a fill I'd hesitate to utilize that method. If you were going in to get a prompt-while-you-wait VIP then maybe draining them yourself is smart.

 

[quimby]

Now... anyone know if it's just a dive shop policy to VIP empty tanks, or is there some regulation or standard that forces a dive shop owner to VIP them?

Once again we have LDS idiotology, there is no requirement for a vip even annually let alone with a empty tank. We can all make up senarios which could lead to a "problem" with a empty tank but it sounds like just plain simple BS here. The whole VIP is a business to business agreement and interpreted by the individual shop; can you say "we have the fox watching the chicken coop". In basis the idea is fine but the interpretation quite often sucks.

 

[quimby]

It's a good idea to VIP any tank that is completely empty. If you suck it dry under water it's going to take on water

Not really, the only way it can get water in is the valve is opened and i.e. rolls around in the bilges etc. Sucking it dry will still have a couple of ats in it, and water aint going upstream. If its got a current VIP there is no real question to me anyway

 

[in_cavediver]

I've always been taught to never let my tank get completely empty, because of the possibility of moisture getting into it. Well, I recently got into a debate with one of my local dive shops on the topic. He wanted me to empty my nitrox tanks before getting there... I explained to him that emptying a tank wasn't in my nature. I prefer to drain it down to 100-200 lbs and let the remainder drain out after I got to the dive shop.

After I got my nitrox tanks filled, I went over to the dive shop I teach out of, and it just so happened that a customer came in, and he wanted his tank filled. When she checked the tank, it was empty. She informed the customer that she would have to do a VIP on the tank. Well, the customer got upset... accused her of trying to make extra money off of him... etc...

Now... anyone know if it's just a dive shop policy to VIP empty tanks, or is there some regulation or standard that forces a dive shop owner to VIP them?

btw... my favorite local dive shop now has nitrox, and they don't empty the tanks before filling. They calculate how much O2 is required to bring the tank up to the requested mixture. It's pretty accurate, too.

Al

First, I am assuming your LDS PP blends nitrox. Having you drain the tanks first makes it easier on them to blend your new nitrox. I am guessing that they want to have empty tanks to ensure just whats in the tanks. It also may be that thier O2 cascade was low and they didn't have the pressure to top up your tanks. There a lots of reasons for not topping up an existing mix.

Now for the VIP/empty tank question. Its a scuba industry thing. DOT regs in US say the tanks have to be hydrostatically tested every five years. That's it. The scuba industry, realizing divers are pretty hard on tanks, has issued the annual VIP requirement. Its really a pretty good idea to look at the condition of the tank and neck threads each year anyway. Its also a really good idea to look in a tank of unknow origins that comes in empty, and see what shape its in.

If I were the person going to fill a tank, when in doubt, I would do a VIP, especially if the tank was empty. Filling the tank is where most tanks fail.

Mike

 

[in_cavediver]

Once again we have LDS idiotology, there is no requirement for a vip even annually let alone with a empty tank. We can all make up senarios which could lead to a "problem" with a empty tank but it sounds like just plain simple BS here. The whole VIP is a business to business agreement and interpreted by the individual shop; can you say "we have the fox watching the chicken coop". In basis the idea is fine but the interpretation quite often sucks.

What it comes down to is who is going to be the one to fill that tank. Since filling is where most tanks fail, its the most dangerous time. Now, do you really blame a guy for saying, hey, you tanks should be looked at each year to make sure that they are up to snuff. Now since I get to fill them, I make the rules about which tanks I fill.

If you really want to make a point, you might ask to see the credentials of the guy inspecting your tank. (If he has any)

Mike

 

[hantzu701]

On one hand, if the tank was empty, wouldn't u want to do a visual before filling the tank? the tank could have been empty for a few hours or a few months.

On the other hand, my LDS has tried to sell me a visual and a hydrotest of my tanks even though the tanks didn't need them. (I hadn't bought the tank from them.)

After I pointed out that the tanks were still in hydro, he still tried to sell me a visual inspection claiming that the visual inspection had expired which it wasn't. I had to point out that yes, I understood how to read the visual inspection stickers too.

I guess it is that time of year when people are getting hydo/visuals, so I guess I shouldn't be so critical of him.

 

[Groundhog246]

Not sure about "requirement", but around here you will not get a fill without a valid visual sticker. In many shops, you won't get a fill without a VIP+ (visual eddy) sticker. Since it's their neck if a tanks bursts, quite literally if their standing beside the tank, I don;t think it's unreasonable. I was by one of the local LDS's today and he's got an AL80 that just failed. He hooked up the eddy tester and shoed me what it shows. Then a light and magnifying mirror and showed me where on the threads you could see the crack (SLC).
As for a VIP on a tank with a valid inspection sticker, but no internal pressure. Who's gonna get sued if there's a problem at depth as a result of water in a tank? Maybe the last shop that filled it? I can see someone up before a judge Yes your honour, I filled the cylinder. As I recall, it had no internal pressure, so it probably had water enter it when it was emptied at depth. Yes your honour, it is industry standard practice to perform a visual inspection on a tank with no internal pressure. No your honour, I didn't inspect the cylinder as the customer (now deceased) assured me it did not need to be inspected, the VIP sticker was still valid and he was sure there was no water or other contaminant in the cylinder. What do YOU think the verdict will be?

If you must blame somebody for the various rules that the industry "forces" upon us, blame the legal system, the insurance companies (who I heard on the radio this morning, made a RECORD PROFIT this past year, in spite of their moaning about mounting losses) and out politicians who let it all happen.

 

[in_cavediver]

Not sure about "requirement", but around here you will not get a fill without a valid visual sticker. In many shops, you won't get a fill without a VIP+ (visual eddy) sticker. Since it's their neck if a tanks bursts, quite literally if their standing beside the tank, I don;t think it's unreasonable. I was by one of the local LDS's today and he's got an AL80 that just failed. He hooked up the eddy tester and shoed me what it shows. Then a light and magnifying mirror and showed me where on the threads you could see the crack (SLC).

You need to be careful with the eddy current testing and VIP+ setups. Luxfer point blank states that the current alloy (6061 I believe), should not have eddy current testing done. Eddy current testing is for the 6351 alloy tanks.

Mike

 

[quimby]

What it comes down to is who is going to be the one to fill that tank. Since filling is where most tanks fail, its the most dangerous time. Now, do you really blame a guy for saying, hey, you tanks should be looked at each year to make sure that they are up to snuff. Now since I get to fill them, I make the rules about which tanks I fill.

Well since I had a shop for over 5 years and filled a whole bunch before VIPs. I have to say a little common sense goes a lot farther than a I make the rules. A lot of shops are requiring their own VIP and not accepting anyone elses, and for that matter doing eddy current testing on 6061's. In fl noone is filling 6351's after last 12/31/03. So do I sound down on a lot of the inspections, in a word yes, and as you said check the inspectors credentials, what the 1 day Bill High's PSI, which is really the only game around. Once again it has been abused so much it has reduced its credability