[PSUBS-MAILIST] air compensation

[Cliff Redus via Personal_Submersibles]

 Vance good to hear from you.  Thanks for your contributions on air/oil compensations.  Always glad when a real expert chimes in.  The statement below was based on using scuba air from dive shop or portable scuba compressor that meets a very high standard for being dry as specied by the air dew point temperature.  This specification says that the temperature would have to drop to below -50F for the first molecules of water vapor to condense to drinking water.  
So seeing ice is really all about how dry is dry.  My guess is the case you describe with using onboard compressors is that the drying was not down to -50F dewpoint.
Hope to see you at next Psub event.
Cliff
    On Wednesday, August 2, 2023 at 08:19:15 AM CDT, vbra676539 at aol.com via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  
 
  Um...well... During normal sub ops we charged HP air with our own onboard compressors. Through dryers, of course. The problem you get is that old Hydrogen and Oxygen thing. Water out of thin air. The US NAvy doesn't call their emergency MBT blow valves the "chicken switches" for nothing. Blowing down chambers and DLO compartments could get pretty chilly, too, depending on how hard and how fast.Vance
    On Wednesday, August 2, 2023, 09:02:56 AM EDT, Cliff Redus via Personal_Submersibles <personal_submersibles at psubs.org> wrote:  
 
  No ice blockage if you use scuba air.  Scuba air is dry, meaning very little water vapor.  Scuba air has a dew point of -50F which is very dry.  To get ice, the water vapor must condense to liquid water then be at a temperature below the freezing point.  Most psubbers use scuba air if they use a BIBS system that is attached to the air used to blow MBT.  As such, they would fill tanks with dry air from a local scuba shop or portable scuba compressor that has a dryer.
Cliff

On Tuesday, August 1, 2023 at 11:18:23 PM CDT, Alan James via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

 
 
 Cliff, (or anyone)Could a large flow through that small orifice cause it toice up? I don't personally know, but had ice forming on a tank valve when I was discharging the contents.Alan

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  On Wed, 2 Aug 2023 at 12:06 pm, Cliff Redus via Personal_Submersibles<personal_submersibles at psubs.org> wrote:   _______________________________________________
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