Thread: Water Extraction from Airline

Originally Posted by Stustoys

Two length of 19 would be even more betterer.
But is "way more" needed? Sure copper might be able to do in 2m* what steel pipe can do in 4m*............ but if you have 4m of steel pipe and the space the end result will be the same.

*insert figures of your choosing.

Stuart

p,s, what does carbonic acid do to copper?

It will dissolve the protective layer of CuO and form copper carbonate which is more or less insoluble in water.
The degree to which it dissolves the Cu this depends on the pH of the water and that depends on what else is in the atmosphere.
I don't believe it's anywhere near as big a problem as rust is in steel pipes around home workshops

Copper has ~5 times the thermal conductivity of iron and for low flow situation a longer narrower pipe is better because there are more collisions with the walls of the container with a narrow pipe.
The specific heat of iron is slightly more than copper and the steel pipe is usually thicker so the iron pipe can absorb more heat but the copper can transfer the heat outside of itself much faster.
The bottleneck will then be the rate at which the outside of the pipe can transfer heat to the atmosphere.
Here a larger pipe (larger surface area) will have an advantage but a set of fins on the copper pipe would easily keep it cool.

LiN₂ tanks have dispensing pipes that have a large set of Al fins on them. This is done for heat transfer the other way, i.e. to prevent then from getting too cold and reduce the amount of icing up during N transfer. Fins could also be added to either pipe to keep the pipe closer to RT. A fn could also be added to help cool the fins.

Originally Posted by BobL

Copper has ~5 times the thermal conductivity of iron and for low flow situation a longer narrower pipe is better because there are more collisions with the walls of the container with a narrow pipe.

Versus the extra speed of the air through the narrower pipe.

Hi Bob, thanks for that.

I meant in parallel. So smaller pipes of the same cross-section.
Going from 19mm to 25mm doubles cross section and adds 30% to the surface area, going to 19mmx2 doubles both.(though maybe twice the length of 19mm would be better still?)

Of course it would cost more.

We are still left with the question of "how much is enough?". Going to have to measure the tank temp next time I fire up to compressor.

Stuart

Originally Posted by Stustoys

Hi Bob, thanks for that.

We are still left with the question of "how much is enough?". Going to have to measure the tank temp next time I fire up to compressor.

Stuart

The original idea came from Michael at Paramount Browns, who used a single very large diameter vertical pipe with ends welded in.

That is inherently dangerous if your welding is not great, and it's galvanised, and as it all comes down to surface area and mass, I just used threaded galv steel pipe in two runs for the same effect.

In use, virtually all of the vapour condensation occurs in the first pipe, so larger/thicker will be better and the more mass the better.

As you need a return line, you might as well make it out of steel and get it to do some work as well.

Just imagine how much heat it would take to even warm those two cold steel pipes of mine - a lot.

So do it how you wish, but the principle holds true regardless.

Cheers

Bob

Originally Posted by BobL

Following a tip from cba-melb, I purchased an automatic variable electrically powered solenoid tank vent valve like this
http://www.ebay.com/itm/1-2-2-way-Au...E:L:OC:AU:3160

Just wondering what other options are there for auto drain taps? Anything local?

Just sharing my condensor setup again.
Coiled copper, goes into the separator, then into the tank.
Has been working well, copper does get warm/hot all the way to the separator when doing a lot of cycles, which isn't often when I do use it.
Took a bit of effort to make (Getting enough sand into the copper, coiling it around a tube, getting it off the tube, getting some of the bends right, getting sand out of the copper) but it was well and truly worth it.