air temp you breath ??

[HeatCker]

when your diving in cold water your losing body heat due to the water temp and due to breathing cool compressed air......is there a way to figure out the temperature of the air that you are breathing while diving ... say your diving in cold water 45 F, top side air temp/tank temp about the same 45 F ... how much does the air temp drop as it goes from the tank, thru the 1st stage to your 2nd stage/lungs ??? thanks

 

[Superlyte27]

20 degrees Fahrenheit below ambient due to Venturi effect

 

[pointy]

20 degrees Fahrenheit below ambient due to Venturi effect

If the air in your tank always dropped by 20 degrees on its way to your lungs via the second stage, then your second stage would freeze flow whenever the water temp is below 52 degrees. I, and many others, have dove in water as cold as 34 degrees without experiencing a freeze flow, so I think that the temperature of the air delivered to your mouth depends on at least two factors: how high the flow rate is through your regulator; and how efficiently your regulator extracts heat from the surrounding water. That could be anything between a negligible drop in temp from the surrounding water to an extreme drop in temp, causing a freeze flow in moderately cold water.

Interesting question though. Are there any other variables that affect the temperature drop between tank and mouth?

 

[tbone1004]

20 degrees Fahrenheit below ambient due to Venturi effect

adiabatic cooling due to the pressure drop does most of it

@pointy it will freeze in 52f water if you let it freeflow. The key is that during exhale you are blowing body temp gas back out and warming everything back up. I can't remember the study, but someone actually measured all of this a while back

 

[JackD342]

Density of air at depth, rapidity of breathing are next on my list. And then a lot more factors that add to freezing.
Here is a great article, and I highly recommend the link at the end of it for even more detail.
Why Scuba Diving Regulators Freeze

 

[tbone1004]

@JackD342 thanks, that was the link I was thinking about