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Metal Housings in Cold Water?

Discussion in 'Tips and Techniques' started by M DeM, Feb 26, 2019.

  1. Storker

    Storker Divemaster

    # of Dives: 100 - 199
    Location: close to a Hell which occasionally freezes over
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    Who the heck is running their AC if it's around freezing outside?
     
    M DeM likes this.
  2. davehicks

    davehicks Barracuda

    # of Dives: 1,000 - 2,499
    Location: Seattle
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    Clearly not a cold water diver! In Seattle it can be 90F outside, and the water is still 48F.

    But seriously, don't be so literal. Fogging can be a problem is hot or cold weather.
     
    M DeM likes this.
  3. leadduck

    leadduck Barracuda

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    Certain types of plastic are not resistant to freezing temperatures, become more brittle and are more likely to crack under pressure. Could be a reason for the recommendation to use metal housings when ice diving.
     
    M DeM likes this.
  4. M DeM

    M DeM Barracuda

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    Crap - I never even thought about the batteries. How long do you suspect you'd get? And curious- did you have fiber optic or sync chords?
     
  5. M DeM

    M DeM Barracuda

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    good to know! Thanks!
     
  6. Bob DBF

    Bob DBF Solo Diver

    # of Dives: I just don't log dives
    Location: NorCal
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    I'm surprised there isn't a way to flush with tank air or an inert gas to purge the housing of moisture.

    @Searcaigh Although I wouldn't want to be in it, sea water freezes at about 28.4 f which would it make it below freezing water to dive. The ice made does not contain salt.


    Bob
    .
     
    Searcaigh likes this.
  7. Akimbo

    Akimbo Lift to Freedom Volunteer Staff Member ScubaBoard Supporter

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    Housings used on deep submersibles and ROVs (Remote Operated Vehicles) are often purged with pure Nitrogen before they are closed. Pure Nitrogen is an ultra-dry gas because it is produced from cryogenic (liquid) gas. You can accomplish nearly the same thing by blowing compressed air from an HP source in the housing before closing. No moisture to condense = no fogging.

    This technique is more likely to be valuable in humid environments than cold climates where the environment is relatively dry. I do it routinely just because electronics hate moisture.
     
    Bob DBF likes this.
  8. bvanant

    bvanant Loggerhead Turtle

    # of Dives:
    Location: Los Angeles (more or less)
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    Well he said above freezing, not 32 or 0 degrees. So yes the temperature of liquid water is by definition above its freezing point (ignoring all sorts of second order effects)
    Bill
     
  9. EireDiver606

    EireDiver606 DIR Practitioner

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    I understand that. He was asking if water has to be above freezing point to be liquid.

    I said it doesn’t. Waters can be -2 degrees Celsius in the coldest part of the world.
     
  10. bvanant

    bvanant Loggerhead Turtle

    # of Dives:
    Location: Los Angeles (more or less)
    2,096
    313
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    We are not communicating. Freezing is a change of state from liquid to solid. The temperature at which is happens depends on many things, like dissolved solids (this is a colligative property), motion of the water, and pressure as well. The fact that pure water at 1 atm freezes at 0C is immaterial here.
    Bill being pedantic
     

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