The water that freezes is, I'm sure, not from the air in the tank. You are
right: that is very, very dry air. It's the water in the natural outdoor air
that is cooled by a super cool jet of recently and quite quickly freed scuba
air.
This isn't speculation: I've seen it and done.
Maybe snow is overstating it: it's not exactly large snowflakes. But there is
definitely condensation coming out of the air in a visible white cloud.
Timothy J. Massey
Sent from my iPad
On Aug 21, 2015, at 1:08 PM, (Redacted sender "JMKrell@xxxxxxx" for DMARC)
<dmarc-noreply@xxxxxxxxxxxxx> wrote:
John,
The compressed air temperature drop will be approx 30 C from 200 to 1 bar.
Reference T-s diagrams for N2. The largest T drop occurs at the first stage
of the regulator, 200 to 10 bar. In water >10 C the 10 bar air is reheated to
near water temperature. Diving in water at temperatures <5 C does present a
regulator freeze issue. Special regulators and procedures are required.
Dumping a full dive tank will not produce snow in the summer. Done that.
SCUBA air dew point of -53 C (<24 PPM H2O).
Krell
In a message dated 8/21/2015 7:05:51 A.M. Pacific Daylight Time,
johndom@xxxxxxxxx writes:
Is there an expansion due air (gas) temperature drop, say from a 200 bar
cylinder to a diver’s mouthpiece after the pressure regulator? Like a JP
expansion effect? Of course with scuba diving, the regulated pressure is
depth dependent, but still. Any values in °C?
jd