Rusty cylinders-need help!

[rob.mwpropane]

The air is super dry, at atmospheric pressure. Not so dry at tank pressure. A -60 dewpoint at atmospheric pressure will allow condensation at 39F and 3500 PSI

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Interesting. Learn something new every day.... but it's still happening in both tanks, and unless he runs them to zero, it almost has to be something the shop / compressor is doing. Yeah?

 

[BRT]

Interesting. Learn something new every day.... but it's still happening in both tanks, and unless he runs them to zero, it almost has to be something the shop / compressor is doing. Yeah?

I was getting tiny rust spots in my tanks. Wondered why, and found the calculator. I sometimes drive over the pass to dive in the winter, temperature can be in the teens or below. I now cool my air to as close as I can get to freezing without it freezing as it leaves the compressor so that when it reaches the water separator it is as cool as possible. Seems to make a difference. My indicating filters never show moisture. If I drop too close to freezing the stainless coil through the coolant bath will clog shut with ice right away. so I keep the coolant bath at 34-35 degrees. Yes, it is a compressor problem, but most people on a coast are not worried about weather below 40 degrees.

 

[Compressor]

The tanks needs to be tumbled then Hydrostatically Tested. That is the safest procedure to do. Visual inspection on its own is not enough as you cannot determine if it can be subject to pressure.

 

[Waterbottle]

Thank you everyone for good anwers. I have had these cylinders under 1 year, so I think rust have came previous owner. It would explain why the largest spots are on samea sides on both cylinders.( I have only keep them upright). Could I dive with these cylinders couple dives or should I maintenance them asap?

 

[grf88]

Did they have the new hydro before you got them or since you purchased them. If they looked like that at hydro time they should not have passed which makes me suspect the hydro. I would have them tumbled and tested before I used them.

 

[halocline]

Judging from the photos, I would get them cleaned out immediately. You can try tumbling them with a good abrasive, and then they might need a bit of final work with a brush. Then they have to be washed with very hot water and dried with air. You will have to find someone knowledgeable to do the work. In many parts of the U.S. this would be the hardest part of the whole project.

 

[Gone for diving]

I was getting tiny rust spots in my tanks. Wondered why, and found the calculator. I sometimes drive over the pass to dive in the winter, temperature can be in the teens or below. I now cool my air to as close as I can get to freezing without it freezing as it leaves the compressor so that when it reaches the water separator it is as cool as possible. Seems to make a difference. My indicating filters never show moisture. If I drop too close to freezing the stainless coil through the coolant bath will clog shut with ice right away. so I keep the coolant bath at 34-35 degrees. Yes, it is a compressor problem, but most people on a coast are not worried about weather below 40 degrees.

How do you cool your coolant bath?
Any pictures of your unit?

 

[BRT]

How do you cool your coolant bath?
Any pictures of your unit?

My unit is fairly hidden in my shop amongst all the tool boxes and stuff. It is an ugly mess, and I'm not gonna post pictures here with all your pretty stuff. The cooling is done with a cooling unit for a water fountain, similar to this Halsey Taylor Remote Chiller Non-Filtered Refrigerated 8 GPH but sourced off of ebay for about $400 new in box. I bypassed the internal thermostat and ran it off of a thermostat in my coolant tank with a small circulation pump.

 

[Gone for diving]

My pretty stuff? Hey I know how it gets
I understand a mess, and I believe in getting most of my gear dirty,

That's a nice idea,,,
I have been thinking about something like that using a bar fridge...

 

[BRT]

My pretty stuff? Hey I know how it gets
I understand a mess, and I believe in getting most of my gear dirty,

That's a nice idea,,,
I have been thinking about something like that using a bar fridge...

The cooler I have now pulls about 5 amps and has no problem keeping up with my tiny compressor. I have no idea how many CFM it would handle, but any cooling is better than no cooling. Just don't let the coolant temperature get too close to freezing or you will deadhead your compressor when the cooling loop freezes the condensate.

My compressor sits on top of a storage cabinet and the nitrox stick is mounted high on the wall above it, out of the way. The cooler sits on a shelf up next to the ceiling around the corner. Oxygen tank sits on the other side of a toolbox by my office door. CO monitor is mounted in the lid of a toolbox beside the compressor. Anybody walking in would not recognize that there is a tank filling system there.