Which Gas is Least Absorbed by Water?

A friend of mine uses compressed air to lift his dock in order to replace Styrofoam blocks as they are worn down. He uses an old inner tube or two. If the tank can have a rubber liner, you would be dollars ahead of any other method.

BTW, CO2 makes great soda water. I'm not sure what nitrogen makes, but most any gas and water should mix fairly easily. Consequently, a barrier will give the best results. Try searching for uncured rubber membrane. Many can be cured with heat in any shape you want.

I would think the differnce would not be noticeable. Air is mostly Nitrogen anyway (70% ish)
Del

Hi Circuit Breaker,

Here's a link:

http://www.engineeringtoolbox.com/gases-solubility-water-d_1148.html

It looks like ~1.7g CO₂ and 0.018g N₂ will dissolve in 1 kg water at 1 Atm and 20ºC - the CO₂ is ~100 times more soluble than N₂.

Go with N₂ or air; air is likely to be much cheaper.

Mike

Thanks! The lake house is about 90 miles away. I wanted to take something to re-float the lift as it is putting strain on the emergency support chains and pulling the dock out of shape. I hope to get the compressor running, but I may have to order a new one, so if my shop-vac won't re-float it and I have to go to compressed gas, I wanted to get as much "life" out of the gas as I can, hopefully enough to get the new compressor in. I thought air was the long term solution, but thought I'd ask! I guess I didn't make that clear in my OP. Thanks again -- JHF

So, I had a 10 gallon aquarium once and it had a tiny little air pump that ran all the time. Do you suppose 2 of them would supply adequate make-up air to keep the floats at the desired level? After the new compressor floats the boat?

I have a boat for sale, if you are interested.

For now, N₂.

the aquarium pump is an excellent idea. frugal, simple and effective. good answer.

Thanks. Have no clue if it would work, but cheap to try.

Been there, done that, it works. Just a hint: the cooler the better for most The higher the pressure the better in any case, Ky.

perhaps plumb in a simple float valve that automatically add air if the float arm gets to far down in the water. Being a slow rate of absorption a small air compressor for the air source would be fine.

If there are no leaks in the compressor or lines before the float valve it should be able to sit in active standby for days at a time between recharge cycles.

CO₂ is highly water soluble; just look at the bubbles released the next time you pop open a can of beer. In contrast, N₂ gas is only soluble at fairly high pressure, which is why divers get the bends when they surface from deep water too quickly.

A good answer I will give you, though of the dark side you are! Much knowledge you have, but ultimately prevail, you will not!

hmm!

Shame that there isn't an option to vote "dangerous answer".

Stick with ordinary air and stay (relatively) safe.

Nitrogen. But, I would caution you to make sure you have a properly vented area. If pure nitrogen is not vented, it will kill you by suffocation. So will CO2, at a high enough concentration. Be safe!

Water in contact with atmosphere is already saturated with air. It will not dissolvee any more. Go with air.

Bioramani

Thanks for the safety warning, but the boat lift is out in the open, on a floating dock 30 ft from shore, no walls or anything to confine any escaping gas. Again, thanks for the reminder, can't be too safe! -- JHF

The two tanks with holes in the bottom - presumably these are scrap?

No, the holes are to let water in or out to raise or lower the lift. There is a pump and some valves to force air into the tanks, forcing the water out, to raise the lift or to let the air out so water can enter to lower the lift and launch the boat. -- JHF

Atmospheric air is the logical choice.

see

Buy one of the helium tanks for ballons and use it.

Thanks. I also have easy access to helium, but since it leaks through "solid" materials, I did not consider it. We use helium to detect leaks that nitrogen will not show. Also, to all who responded, it became a moot point when I got to the dock yesterday. The pump did work, the GFI was tripped. Thanks again to all who responded. -- JHF