Air warmer for cold diving

[Soggy]

If you can't afford the right undergarment that will keep you warm enough, you shouldn't be doing the dives. Warming the air is looking in the wrong place.

If you do have a decent undergarment, there are heating systems available to augment the undergarment. Check out ekpp.org...these guys do very long dives in very cold water and use heaters for comfort on their deco. Unless you are doing very long dives, there is no reason to have one of these. If me and my 6', 150 lb frame can spend an hour in 34 degree water, anyone can.

 

[DA Aquamaster]

If you can't afford the right undergarment that will keep you warm enough, you shouldn't be doing the dives. Warming the air is looking in the wrong place.

If you do have a decent undergarment, there are heating systems available to augment the undergarment. Check out ekpp.org...these guys do very long dives in very cold water and use heaters for comfort on their deco. Unless you are doing very long dives, there is no reason to have one of these. If me and my 6', 150 lb frame can spend an hour in 34 degree water, anyone can.

You're kinda bashing him there with the "if you can't afford..." type comment and you are missing the point, that he actually has a point.

Commerical operators have found that heat loss from breathing cold gases including air is significant so there is nearly as much value in pumping warm air to the diver as there is pumping warm water to the suit. Divers do lose a lot of heat through respiration even on air and if you go with helium mixes, it gets significantly worse.

Personally, I am open to any novel idea that may help make diving safer or more comfortable. Air warming for cold water recreational divers is an idea with merit. The fact that there is currently not an effective was to achieve it does not mean the idea has less merit. If divers just accepted that the way things are done now is good enough, we would all still be diving with 38 cu ft steel tanks, double hose regs, round window single skirt masks and no form of bouyancy compensation.

 

[Soggy]

No bashing was intended, and I wasn't aware he was doing a commercial dive. You are right...heat loss thru breathing gas is a major cause of heat loss. The only way to solve that is a rebreather or a completely redesigned 2nd stage.

That being said, the point to be taken away is that dives in this temperature range can be done safely and comfortably without the need for gadgets such as this.

Incidentally, heat loss thru breathing helium is not increased. There is a thread about it here somewhere as well as an article over on decompression.org. Helium only affects heat loss if used as a suit inflation gas.

You're kinda bashing him there with the "if you can't afford..." type comment and you are missing the point, that he actually has a point.

Commerical operators have found that heat loss from breathing cold gases including air is significant so there is nearly as much value in pumping warm air to the diver as there is pumping warm water to the suit. Divers do lose a lot of heat through respiration even on air and if you go with helium mixes, it gets significantly worse.

Personally, I am open to any novel idea that may help make diving safer or more comfortable

 

[O2BBubbleFree]

What about a wetsuit on the hose? Humor me for a moment...

On another thread there was talk of re-routing the exhaled gas to get the bubbles away from the mask. Particularly useful for photographers...

So, maybe we can expand on this and create a heat-exchanger to warm the incoming gas? Killing two birds with one stone, as it were.

Cover the gas hose with a neoprene sleeve a little larger than the gas hose. Tie the bottom end to the exhaust tee on the regulator, so that warm exhaust gas passes through the length of the sleeve. The neoprene will provide insulation, as well as contain a layer of water that is warmed by the exhaled gas passing through it. The warmed water will in-turn warm the gas hose. What do you think?

I was first thinking of an air-filled sleeve, but that would be really buoyant. The water-filled neoprene sleeve would be buoyant, but not as bad as air-filled. But it may still need weight added, like some rebreather hoses use.

The majority of the sleeve needs to be fairly loose-fitting, so that the exhaust air passes easily through the hose. Also, if the sleeve is loose-fitting, then it can expand and contract as the air passes through. If it is rigid, then the air passing out would be replaced by cold water passing in. The first-stage end needs to be just loose enough to let the air pass out, but tight enough to reduce water exchange.

It might also need a one-way valve at the exhaust tee to prevent re-breathing CO2, but I think that if the sleeve is flooded this wouldn't be necessary.

I would have to dig out my Thermodynamics book to see if the warm air would warm the trapped water well enough to warm the gas hose well enough to warm the incoming gas well enough do any good (taking into account the heat loss through the neoprene), and I ain't a gonna do that.

You might also be able to ‘pre-heat’ the heat exchanger by filling it with warm water prior to the dive, like some do with wetsuits.

Remember me when you bring this idea to market. ;^)

 

[pipedope]

Extreemly cold air is a real problem, especially in commercial work where you may turn on a tank that is at high pressure as your bailout supply.

The higher the pressure difference between the tank and the IP (intermediate pressure) the colder the air will be.

The trick is to warm the air to water temperature. Remember the ice forming on the first stage?
There are gear makers working on heat exchangers to do just this. I doubt that it will ever be something for sport diving but it is on the drawing board and in the test labs.

 

[O2BBubbleFree]

'Course, as Doc Intrepid quipped, a rebreather solves both the cold air problem and the bubble problem I mentioned...

 

[mikerault]

Actually the major cooling affect is from any liguid state material (such as water) that flashes to vapor because of the pressure change sucking the energy from the surrounding gas as it does so. Otherwise in close to zero degree C water you would be pulling in air at -40 to -50 degrees, nope, don't buy it.

The second stage is merely a spring loaded door that opens on demand, it usually doesn't do any pressure reduction on its part.

Mike

 

[seakdivers]

Oh for petes sake..........

 

[mikerault]

Ok, I stand corrected...been a while since chemistry class.

 

[Xman]

...snip...It might also need a one-way valve at the exhaust tee to prevent re-breathing CO2, but I think that if the sleeve is flooded this wouldn't be necessary.....snip...
Remember me when you bring this idea to market. ;^)

Ahhhh, no. I will remember that you talk as though you don't have a one way valve on your exhaust from your 2nd stage. If you are at risk of rebreathing CO2, would you not ordinarily be at risk of inhaling water???
I don't think people will be falling over themselves to patent this idea, but congratulations on the imaginative ideas. Back to the drawing board though. The temperature difference between the sleeve and the gas would not be enough to do any measurable amount of warming given the hoses' insulation in between.

That said, I can't say that I have any better ideas, apart from the often already mentioned -wear warmer exposure protection so it doesn't matter.