Emptying a tank ...

[Tanker299]

This has been bugging me for a while , so here it goes:

You have done your last dive of the season and realized that the good Samaritans (elves) at your LDS have filled your tank.
You get home and read the many posts saying that you should only leave 100 - 500 PSI on the tank for extended periods of non-use.
So, you do the following:

Open the valve:
Slow?
Fast?
Irrelevant?

Slow, takes for ever
Fast, frost forms

What's the best/recommended? And if it is fast and frost forms, what is the worst case scenario?

Thanks !

Alex

 

[JohnW]

Like most things in Scuba Slower(within reason) is better. I'll let others with more experiance elaborate.

 

[deepblueme]

Slow and come back after the Simpsons are over and see if it is empty.

Frost can form water in a tank and we know what that can do.

What is an extended peroid? More than 6 months? Drain it, less leave it full.
In a steel tank the o2 can be used up by rust forming( it takes along time) with an al tank it coats over and the oxadizing prosses pretty much stops.

 

[JohnW]

You have done your last dive of the season and realized that the good Samaritans (elves) at your LDS have filled your tank.

I also think this is a good reason to do just one more dive.

 

[Tanker299]

Frost can form water in a tank and we know what that can do..

Darn, we may have a problem then ... :shakehead

How to check? What is the corrective action if one suspects this?

Beginning to think this is my lesson for the year regarding diving ... :water:

Thanks !

Alex

 

[MichaelBaranows]

Maybe I am wrong but I have been told to leave tank full not empty.

 

[b1draper]

I would say if you keep your tanks in side your house there shouldn't be a problem. If you suspect there's a problem take your tank to your LDS and have them do a cleaning or you can just call the LDS and get their opinion.

Personally, I live in Florida and I keep my tanks in my house and there hasn't been a problem. I would have any tank inspected if it's been sitting for a REALLY long time, more so with steel tanks because of the rust concerns.

 

[deepblueme]

You should always leave some air in the tank so water and critters can't get inside and so you don't have to shell out the bucks for a viz inspection next time you get it filled.
I did a viz on an empty tank that had a little spider and lots of cobwebs inside.

As for water in the tank, if it is TOTALLY empty of air, turn on the valve cuz air in the tank can expand, take out the valve turn the tank over and let it drain/dry for a couple of days.
In the shop we used an air tube to blow it out. Then take it to you LDS for an inspection an low fill till you are going to use it.

 

[scarefaceDM]

Put the tank in a nice dry area. Out of heat, sun, humidity and cold. If your storing your tank for the season/over the winter. It is best to leave it full. if you have a half tank or a very low tank volume, chances are you will develop some condensation especially in Steel tanks. . Leaving a steel tank half empty or with low volume, your looking into a possible internal tank cleaning due to rust

Emptying a tank for a VIP...simply let it drain slowly. open valve until you hear a HISSSSS... Bring it to the dive shop for a VIP or what ever.

 

[Sharky1948]

It is best to leave it full. if you have a half tank or a very low tank volume, chances are you will develop some condensation especially in Steel tanks. Leaving a steel tank half empty or with low volume, your looking into a possible internal tank cleaning due to rust

Help me understand why. It seems to me that more pressure means higher ppO2 and therefore faster oxidation. The only thing I can think of is that lower pressure allows water to condense easier. But, if you are getting dry fills, that shouldn't be a real concern unless at some point you've drained the tank and allow water to back-fill.

I'm probably all wet , so let me know!