Water inside your air tanks...

[Dive-aholic]

Bad fills. Condensation cannot build up in a tank that has more pressure than the atmospheric pressure, no matter how quickly you release the air. If the pressure inside the tank is greater than atmospheric, you will have nothing but air. So, if you truly never emptied your tanks, then the moisture must have been forced into the tanks, meaining the shop is filling your tanks with very moist air.

 

[PerroneFord]

Yep, it's the fills. Some compressors are known for doing this (according to my instructor who has a ton of experience with compressors and boosters).

I will now spin the valve off any tank I feel is dicey and have a look inside.

 

[Nemrod]

I would have those tanks tumbled clean to prevent any pitting and then switch shops. An empty tank with the valve closed despite urban legend will not get water in it but of course if the valve is open and and you put it in water some will of course get in there. I don't think you did that.

The most common way to get water in the tank is to connect the whip to the tank valve after the tank was dunked into the fill bath letting a tiny bit of water into the upper valve chamber--then when it is pressurized and the valve opened that water is injected into the tank. The other way of course is for the fill system to have water in it. Compressed air has gone through several compresion cycles and thus should be dry but perhaps they have a bad filter. This is exctly why steel tanks fell out of favor way back--high maintenence--you must have a look see into them regularly to prevent pitting rust. N

 

[Walter]

Not necessarily the fills, but the filling process, of which you are likely to blame. When a tank is filled, the whip is attached and everything and anything located between the opening of the whip and the orifice of the valve is going into the tank when the whip and valve are opened. If water is there, it's going in.

After diving, tanks (and valves) are often exposed to sea stray, rain and water from rinsing. Unless you religiously blast water from the valves prior to taking your tanks in to be filled, that water is going into the tank. While I'm sure they exist somewhere, I personally know of no fill station that blasts water from tank valves prior to filling. Do you blast your valves clean prior to filling?

 

[Dive-aholic]

All the shops I visit in N. Fl blast the valves clean prior to filling. It's just standard practice there. I have not seen that anywhere else, though, but I do blast them myself.

Interesting point, Walter.

 

[Scared Silly]

This month I inspected my AL tanks and found that one had some alunimum oxide on the sides many very small spots evenly along the tanks wall and bottom. Not much but after examining it I found that it was probably from one fill where there was probably water in the valve. The reason I believe this is because the vast majority of the oxide was in the lower 2/3 of the tank. Very little was in the top 1/3 of the tank. There was no water present otherwise. Given that the dip tube acts as a nozzle it made for a very even spray.

So given that you have a measurable amount of water I would say it was not from moisture in the valve but from water in the system.

I would make trip into the other dive shop ask for the owner and to see the maintaince records - something that should be done before getting a fill anyways.

 

[SparticleBrane]

Do you blast your valves clean prior to filling?

I sure do...
I blast them after I get out of the water and before I fill them. In fact that's SOP where I get my tanks filled.

 

[Bob3]

Do you blast your valves clean prior to filling?

You betcha, that's from tank filling 101.
Folks that use water baths are *usually* in the habit of clearing their valves.

 

[cummings66]

After diving, tanks (and valves) are often exposed to sea stray, rain and water from rinsing. Unless you religiously blast water from the valves prior to taking your tanks in to be filled, that water is going into the tank. While I'm sure they exist somewhere, I personally know of no fill station that blasts water from tank valves prior to filling. Do you blast your valves clean prior to filling?

I do this myself and one day on the boat a guy says why are you doing that? I explained that often with my DIN valve that water is in the threads after I remove the reg and I don't know that the shop blasts it clear, so I do it and that way I know they will not get water in my tank.

The DM overheard me and said you know that's a really good idea and the boat learned something good that day.

I was taught that in my Padi Ow class, but I had a pretty good instructor who tossed in lots of tidbits here and there. This isn't common, I've only seen two other divers do that.

 

[dschulte]

Do you blast your valves clean prior to filling?

Towel dry and then store on there sides with the DIN down incase I missed anything. Both shops I frequent crack valves prior to filling to push anything out of the area.

I will be super-drying all my DIN valves in the future.