Water in tank

[darylm74]

I went to my LDS to get my steel 95 tanks Nitrox filled the other day and found out that they wouldn't be ready in time for my upcoming trip since the blender has been very sick. The pre-mix was too low to fill mine and my tanks aren't O2 clean. My best friend and the dive shop manager suggested another shop that they work with often. I took them to the other shop and the guy told me that though they do bank Eanx 32, but they require all tanks to be O2 cleaned, which he could do in time. I'm going to Gilboa and understand they only do partial pressure and wanted them O2 cleaned anyway so I said sure. The tanks I got were just hydro'd/vis'd at the beginning of the summer and I've only had them in the water a few times. I get a call today and the guy told me that there was a bit of water and decent amount of rust in the tanks. He also said the one was pitted. He said they needed shipped out to be tumbled and would not be ready for this weekend. The cost was minimal but what bothers me is I have no idea how the water got in the tanks. The guy that does the work at my normal shop and did the hydro/vis does not make mistakes, especially like that. The tanks go on a drying rack for a couple days upside down just to make sure there is no water in it. The tanks have never been below 800 psi either. The guy at the new shop also called my normal shop yesterday and made a bit about the dive shop manager's best friend coming to him for service (though he knows the state of the service guy at my shop and why I was there).

Is it me or am I getting burned here? Or, is there another way water could get in without me knowing. The tanks were always filled at my shop and I know the kind of business they run, very clean and the compressors are always taken care of. I also know my best friend would be on top of it if there was a problem since he is the manager and also gets his tanks filled there too.


*frustrated* :mad1:

Daryl

 

[ScubaSarus]

Thats suspicious. Take em back to the original shop for reinspection on the house. Its only been a few months since vis. Ask em if it could have pitted that soon and both tanks ? Thats odd. Yes I can see 1 tank but not both.

 

[Doc Intrepid]

Do you have your tanks filled anywhere where they place the tanks in water while being filled? This is a pretty common means of introducing water vapor into steel tanks - droplets of water get on the whips and are introduced into the tank via the valve when people get in a hurry. Your tanks wouldn't need to be below 800 psi, as the water was blown into the tanks during the fill process. Its the only explanation I can think of. A couple other are that the guy screwed up during the rinse cycle and flash rusted your tanks. I'm not accusing, but...its certainly a bit odd.

Best thing you can do if you're truly frustrated, is see your LDS owner and take the PSI VIP course and possibly a blenders course. Work it with your LDS owner so that you take the course from him and in return, you get to VIP your own tanks annually and fill them with nitrox each time. The only guy who screws with your tanks is then you. Plus, while it eats up more of your time, you know how things work and know that the work is done right. Plus, blending your own gas is never a bad thing.

Worth pondering...

Doc

 

[darylm74]

Hmmm, they do put them in water and the last person who filled them (with air) was a newbie at it. That could have been the situation. She's also a very good friend (i.e. at my house hanging with my wife 3 or 4 times a week) so touchy with pointing fingers there.........but point well taken.

The tanks were a trade from my best friend (and my LDS's general manager). He had them hydro'd/vis'd right before the trade. Prior to this incident he did mention taking the VIP and a blender class together. Definitely think I will consider it now. The problem is their tech guy that does all the blending and so forth has some health problems and he hasn't been available to do as much lately and their backup guy has a full time job and is rarely there. If it had not been I needed them this weekend I would have had them do it at my LDS instead of going to the other place. At least my best friend is lending me some of his tanks for the weekend.

 

[captndale]

I went to my LDS to get my steel 95 tanks Nitrox filled the other day and found out that they wouldn't be ready in time for my upcoming trip since the blender has been very sick. The pre-mix was too low to fill mine and my tanks aren't O2 clean. My best friend and the dive shop manager suggested another shop that they work with often. I took them to the other shop and the guy told me that though they do bank Eanx 32, but they require all tanks to be O2 cleaned, which he could do in time. I'm going to Gilboa and understand they only do partial pressure and wanted them O2 cleaned anyway so I said sure. The tanks I got were just hydro'd/vis'd at the beginning of the summer and I've only had them in the water a few times. I get a call today and the guy told me that there was a bit of water and decent amount of rust in the tanks. He also said the one was pitted. He said they needed shipped out to be tumbled and would not be ready for this weekend. The cost was minimal but what bothers me is I have no idea how the water got in the tanks. The guy that does the work at my normal shop and did the hydro/vis does not make mistakes, especially like that. The tanks go on a drying rack for a couple days upside down just to make sure there is no water in it. The tanks have never been below 800 psi either. The guy at the new shop also called my normal shop yesterday and made a bit about the dive shop manager's best friend coming to him for service (though he knows the state of the service guy at my shop and why I was there).

Is it me or am I getting burned here? Or, is there another way water could get in without me knowing. The tanks were always filled at my shop and I know the kind of business they run, very clean and the compressors are always taken care of. I also know my best friend would be on top of it if there was a problem since he is the manager and also gets his tanks filled there too.


*frustrated* :mad1:

Daryl

It is a common misconception among divers that the air in their tanks is perfectly dry. In fact, even with an atmospheric dew point in the range of -50 to -60 degrees F there is condensation on the sides of the tank when it is at rated pressure and at low temperature. This is normal and is the reason that we have small amounts of rust in steel tanks. Steel tanks should be stored at reduced pressure and always vertical. Reducing the pressure reduces the condensation. Storing in a vertical position causes any rust to form in the bottom of tha tank, which is much thicker than the sides.

 

[ScubaSarus]

Excellent info captdale. I didn't know they were not totally dry. I always assumed dryness unless breached.

 

[oxyhacker]

I think the PSI course is of limited use to the individual diver now that the certification requires a $125 or so refresher every 3 years, unless he/she owns a heck of a lot of tanks. Especially because there's a lot of shops that won't honor non-shop inspections/generic stickers anyhow.

That said, it is well worth any serious diver's time to learn to inspect his/her own tanks, even if informally. You can do it by downloading the Luxfer manual, or buying Bill High's (PSI) book. Then you can pre-inspect them before you take them to the shop, take care of any obvious problems like surface rust or moisture - and have no surprises. If a shop tries to hose you, you'll know it.

I do agree that if one takes a PSI course, it's a good idea to do it through a local shop, mainly because they will then be more likely to accept your inspections, and perhaps more important, will be available when you need a second opinion inspecting a tank. And I agree that blending your own gas is never a bad thing ;-)

Best thing you can do if you're truly frustrated, is see your LDS owner and take the PSI VIP course and possibly a blenders course. Work it with your LDS owner so that you take the course from him and in return, you get to VIP your own tanks annually and fill them with nitrox each time. The only guy who screws with your tanks is then you. Plus, while it eats up more of your time, you know how things work and know that the work is done right. Plus, blending your own gas is never a bad thing.

Worth pondering...

Doc

 

[rgbmatt]

Hmmm, they do put them in water and the last person who filled them (with air) was a newbie at it. That could have been the situation. She's also a very good friend (i.e. at my house hanging with my wife 3 or 4 times a week) so touchy with pointing fingers there.........but point well taken.

If you get your tanks filled at a place with a water bath, watch them very closely to make sure nothing dumb happens - there's lots of potential for it. Sometimes, the whip gets dropped in the water by accident, the tank slips and falls into the water, etc. etc. Wet fills are bad in general, but especially so for steel tanks!

Also, if your steel tanks have been hydroed recently, they may have some flash rust from the hydro test. Usually there's not enough to warrant tumbling, though.

 

[ScubaSarus]

I would assume any rust however slight in the tank would require tumbling but just not a hole lot of tumbling. Correct me though if I'm wrong. I'm not too sure if the is a acceptable limit of rust in a tank. That flash rust I never knew about and would like to know more.

Take care.

 

[oxyhacker]

The inside of a steel tank is absolutely bare steel which will rust almost instantly in the right circumstances. Flash rust is very light rust spread out over a large area, visible usually as a reddish haze, which is almost impossible to avoid in some tanks without using chemicals. Trying to remove every last bit is often counterproductive, as after tumbling or whipping you have to clean out the residue, which means washing the tank again, which means getting it wet again. This can be avoided, sometimes, by using a whip and then blowing the tank out thoroughly with clean dry scuba air rather than washing it again, to avoid introducing more moisture.

Usually flash rust forms as a result of moisture after a O2 cleaning or hydro, however it usually doesn't get worse from one inspection to the next at any appreciable degree with use as long as the tank is fed a diet of properly dry scuba air. So light flash rust is permissable under most tank inspection standards, and PST even describes it as normal in some of their recent literature.

If the rust starts concentrating in spots, then it becomes a problem because it can cause pitting which will damage the tank. This it easily visible because the rust will how up as a pattern of spots or lines rather than being evenly distributed.

I would assume any rust however slight in the tank would require tumbling but just not a hole lot of tumbling. Correct me though if I'm wrong. I'm not too sure if the is a acceptable limit of rust in a tank. That flash rust I never knew about and would like to know more.

Take care.