Negative pressure

Discussion in 'Digital Photography' started by Dave, Feb 15, 2004.

  1. Dave

    Dave Guest

    I'll be flying out of the US and want to store my Oly 5050 digicam inside
    it's UW housing to save space. It'll travel in my carry-on bag (I never
    check stuff). There's no good way to put the camera in without sealing the
    housing. I know the housing is good to 130 feet of positive pressure, but I
    wonder if there is any danger of the slight negative pressure in the cabin
    damaging any of the seals on the housing? My old Pelican cases had purge
    values to deal with this issue, but the Oly housing doesn't.

    Thoughts?

    TIA,

    Dave


    --
    "Every normal man must be tempted at times to spit upon his hands,
    hoist the black flag, and begin slitting throats."

    - HL Mencken
    Dave, Feb 15, 2004
    #1
    1. Advertising

  2. Dave

    Alan Street Guest

    In article <>, Dave
    <> wrote:

    #I'll be flying out of the US and want to store my Oly 5050 digicam inside
    #it's UW housing to save space. It'll travel in my carry-on bag (I never
    #check stuff). There's no good way to put the camera in without sealing the
    #housing. I know the housing is good to 130 feet of positive pressure, but I
    #wonder if there is any danger of the slight negative pressure in the cabin
    #damaging any of the seals on the housing? My old Pelican cases had purge
    #values to deal with this issue, but the Oly housing doesn't.
    #
    #Thoughts?
    #
    #TIA,
    #
    #Dave
    #
    #

    You won't damage the o-rings or seals, but you will almost certainly
    have problems opening the housing after you land (which is why Pelican
    cases have vent valves). Remove the main o-ring before you fly.

    Alan
    Alan Street, Feb 15, 2004
    #2
    1. Advertising

  3. Dave

    Joe English Guest

    Alan Street wrote:
    > In article <>, Dave
    > <> wrote:
    >
    > #I'll be flying out of the US and want to store my Oly 5050 digicam inside
    > #it's UW housing to save space. It'll travel in my carry-on bag (I never
    > #check stuff). There's no good way to put the camera in without sealing the
    > #housing. I know the housing is good to 130 feet of positive pressure, but I
    > #wonder if there is any danger of the slight negative pressure in the cabin
    > #damaging any of the seals on the housing? My old Pelican cases had purge
    > #values to deal with this issue, but the Oly housing doesn't.
    > #
    > #Thoughts?
    > #
    > #TIA,
    > #
    > #Dave
    > #
    > #
    >
    > You won't damage the o-rings or seals, but you will almost certainly
    > have problems opening the housing after you land (which is why Pelican
    > cases have vent valves). Remove the main o-ring before you fly.
    >
    > Alan

    I thought you had to pack it in water
    Joe English, Feb 16, 2004
    #3
  4. "Dave" <> writes:

    > I'll be flying out of the US and want to store my Oly 5050 digicam inside
    > it's UW housing to save space. It'll travel in my carry-on bag (I never
    > check stuff). There's no good way to put the camera in without sealing the
    > housing. I know the housing is good to 130 feet of positive pressure, but I
    > wonder if there is any danger of the slight negative pressure in the cabin
    > damaging any of the seals on the housing? My old Pelican cases had purge
    >SNIP<


    I have flown with my Nikonos camera in checked bags, then used it
    underwater. No problems with seal damage, nor with opening the camera on
    land. I did take normal care of the seal, and grease it before use as
    directed in the manual. I don't know what pressure is maintained in the
    checked baggage area, but I suspect it will be the same as or less than in
    the passenger cabin.
    --
    Philip Stripling | email to the replyto address is presumed
    Legal Assistance on the Web | spam and read later. email to philip@
    http://www.PhilipStripling.com/ | my domain is read daily.
    Phil Stripling, Feb 16, 2004
    #4
  5. Dave

    Eric Guest

    "Dave" <> wrote in message
    news:...
    > I'll be flying out of the US and want to store my Oly 5050 digicam inside
    > it's UW housing to save space. It'll travel in my carry-on bag (I never
    > check stuff). There's no good way to put the camera in without sealing the
    > housing. I know the housing is good to 130 feet of positive pressure, but

    I
    > wonder if there is any danger of the slight negative pressure in the cabin
    > damaging any of the seals on the housing? My old Pelican cases had purge
    > values to deal with this issue, but the Oly housing doesn't.


    Interesting question. On my trips, I pack the housing with the door
    open with clothes packed around it to keep it from getting damaged. The
    suggestion that others have made to remove the main O-ring sounds like an
    even better idea however.

    -Eric
    Eric, Feb 16, 2004
    #5
  6. Dave

    Dave Guest

    "Phil Stripling" <> wrote in message
    news:...
    > "Dave" <> writes:
    >
    > > I'll be flying out of the US and want to store my Oly 5050 digicam

    inside
    > > it's UW housing to save space. It'll travel in my carry-on bag (I never
    > > check stuff). There's no good way to put the camera in without sealing

    the
    > > housing. I know the housing is good to 130 feet of positive pressure,

    but I
    > > wonder if there is any danger of the slight negative pressure in the

    cabin
    > > damaging any of the seals on the housing? My old Pelican cases had purge
    > >SNIP<

    >
    > I have flown with my Nikonos camera in checked bags, then used it
    > underwater. No problems with seal damage, nor with opening the camera on
    > land. I did take normal care of the seal, and grease it before use as
    > directed in the manual. I don't know what pressure is maintained in the
    > checked baggage area, but I suspect it will be the same as or less than in
    > the passenger cabin.
    >


    I haven't had any problem with my UW cameras either, but the Oly housing has
    a LOT more volume and a ton of o-ring sealed controls. I'm afraid that
    either I'll never be able to get it open again, or that one of the little
    o-rings will slip out if place and leak or get jammed.

    After doing some repacking today, it looks like I'll be able to take the
    divider out of my Domke bag, use it for the accompanying gear, and pack the
    camera in the housing on the side with the main o-ring removed.

    Thanks all,

    Dave
    Dave, Feb 16, 2004
    #6
  7. Dave

    Alan Browne Guest

    Dave wrote:

    > I'll be flying out of the US and want to store my Oly 5050 digicam inside
    > it's UW housing to save space. It'll travel in my carry-on bag (I never
    > check stuff). There's no good way to put the camera in without sealing the
    > housing. I know the housing is good to 130 feet of positive pressure, but I
    > wonder if there is any danger of the slight negative pressure in the cabin
    > damaging any of the seals on the housing? My old Pelican cases had purge
    > values to deal with this issue, but the Oly housing doesn't.
    >


    First off, there is no such thing as "negative pressure"

    The cabin pressure in an airliner is about 8,000' when the aircraft is
    at 30,000 - 35,000 feet.

    As a rule of thumb, it is about 1" (Hg) per 1,000 feet of altitude at
    low altitudes .... so if the pressure in the enclosure is 1 atmos. the
    pressure against the seals will be about 8" Hg ... about 0.3 atmospheres.

    It is pressing in the sense opposite that when under water, but surely
    the enclosure will tolerate that? Does the manufacturer have any
    information at their website about carrying on aircraft?

    Is there something on the enclosure you can leave open?

    Cheers,
    Alan.




    --
    e-meil: there's no such thing as a FreeLunch.
    Alan Browne, Feb 16, 2004
    #7
  8. Dave

    Rich Lockyer Guest

    On Sun, 15 Feb 2004 16:16:05 -0600, "Dave" <>
    wrote:

    >I'll be flying out of the US and want to store my Oly 5050 digicam inside
    >it's UW housing to save space. It'll travel in my carry-on bag (I never
    >check stuff). There's no good way to put the camera in without sealing the
    >housing. I know the housing is good to 130 feet of positive pressure, but I
    >wonder if there is any danger of the slight negative pressure in the cabin
    >damaging any of the seals on the housing? My old Pelican cases had purge
    >values to deal with this issue, but the Oly housing doesn't.


    I remove the O-ring and pack it separately.


    --- Rich
    http://richlockyer.tripod.com/
    Rich Lockyer, Feb 16, 2004
    #8
  9. Dave

    Mark M Guest

    "Alan Street" <alan@nonono_irsi.com> wrote in message
    news:150220041455314758%
    > You won't damage the o-rings or seals, but you will almost certainly
    > have problems opening the housing after you land (which is why Pelican
    > cases have vent valves). Remove the main o-ring before you fly.
    >
    > Alan


    I would think that problem would exist ONLY if you open it at altitude.
    If you close it on the ground...and don't open it until you're again on the
    ground, the pressure inside shouldn't change, should it?
    Mark M, Feb 16, 2004
    #9
  10. Dave

    Tom Thackrey Guest

    On 16-Feb-2004, "Mark M" <> wrote:

    > "Alan Street" <alan@nonono_irsi.com> wrote in message
    > news:150220041455314758%
    > > You won't damage the o-rings or seals, but you will almost certainly
    > > have problems opening the housing after you land (which is why Pelican
    > > cases have vent valves). Remove the main o-ring before you fly.
    > >
    > > Alan

    >
    > I would think that problem would exist ONLY if you open it at altitude.
    > If you close it on the ground...and don't open it until you're again on
    > the
    > ground, the pressure inside shouldn't change, should it?


    It depends on where you land. Think LA to Denver.

    --
    Tom Thackrey
    www.creative-light.com
    tom (at) creative (dash) light (dot) com
    do NOT send email to (it's reserved for spammers)
    Tom Thackrey, Feb 16, 2004
    #10
  11. Dave

    Dave Guest

    "Mark M" <> wrote in message
    news:Rv1Yb.4911$hE.841@fed1read07...
    >
    > "Alan Street" <alan@nonono_irsi.com> wrote in message
    > news:150220041455314758%
    > > You won't damage the o-rings or seals, but you will almost certainly
    > > have problems opening the housing after you land (which is why Pelican
    > > cases have vent valves). Remove the main o-ring before you fly.
    > >
    > > Alan

    >
    > I would think that problem would exist ONLY if you open it at altitude.
    > If you close it on the ground...and don't open it until you're again on

    the
    > ground, the pressure inside shouldn't change, should it?
    >
    >


    I would think so too, but I FINALLY found the Oly documentation (page 147,
    thank-you-very-much) and they say to pull both o-rings before flying. I'll
    just put them in one of the little bags they give you for lubricating them
    and all should be fine.

    Thanks all!
    Dave, Feb 16, 2004
    #11
  12. "Mark M" <> writes:

    >I would think that problem would exist ONLY if you open it at altitude.
    >If you close it on the ground...and don't open it until you're again on the
    >ground, the pressure inside shouldn't change, should it?


    Only if it remains sealed. But underwater cases are designed only for
    the situation where pressure is higher outside the case than inside,
    where pressure forces the case halves to close more tightly on the
    O-ring. In a situation where the pressure inside the case is higher,
    the case halves are forced apart and the seal will leak, equalizing the
    pressure.

    Thus, as the plane climbs, the cabin altitude rises to 6000-8000 feet,
    and the housing will leak outward enough to bring the pressure inside it
    to somewhere near that level. Then when the plane descends, the housing
    clamps onto the O-ring and fails to leak. When you get back on the
    ground, you've got a substantial pressure difference between inside and
    outside.

    Dave
    Dave Martindale, Feb 16, 2004
    #12
  13. Dave

    Alan Street Guest

    In article <Rv1Yb.4911$hE.841@fed1read07>, Mark M
    <> wrote:

    #"Alan Street" <alan@nonono_irsi.com> wrote in message
    #news:150220041455314758%
    #> You won't damage the o-rings or seals, but you will almost certainly
    #> have problems opening the housing after you land (which is why Pelican
    #> cases have vent valves). Remove the main o-ring before you fly.
    #>
    #> Alan
    #
    #I would think that problem would exist ONLY if you open it at altitude.
    #If you close it on the ground...and don't open it until you're again on the
    #ground, the pressure inside shouldn't change, should it?
    #
    #

    Not necessarily. Some seals will hold pressure from either direction,
    but many seals used in housings are designed to withstand external
    pressure and vent internal pressure. Since the cabin of an airplane is
    pressurized to an equivalent of ~7000 ft, many housings will vent when
    the plane is at altitude and seal upon descent. Anyone who has used a
    Pelican case onboard has seen this (as an aside, venting a Pelican case
    next to a TSA inspector can be great fun.... if you're not in a hurry
    to catch your next plane ;-).

    Alan
    Alan Street, Feb 16, 2004
    #13
  14. Dave

    de Valois Guest

    Dave left this mess on Sun, 15 Feb 2004 16:16:05 -0600 for The Way to clean up:
    >
    >I'll be flying out of the US and want to store my Oly 5050 digicam inside
    >it's UW housing to save space. It'll travel in my carry-on bag (I never
    >check stuff). There's no good way to put the camera in without sealing the
    >housing. I know the housing is good to 130 feet of positive pressure, but I
    >wonder if there is any danger of the slight negative pressure in the cabin
    >damaging any of the seals on the housing? My old Pelican cases had purge
    >values to deal with this issue, but the Oly housing doesn't.
    >
    >Thoughts?
    >


    Never seal your casing on a plane. Next?

    Tao te Carl
    "It takes a village to have an idiot." - Carl (c) 2003

    (Kudos to Cap'n Jim Wyatt for this link) BEFORE you ask a dumb-ass question
    here...http://www.speakeasy.org/~neilco/bart.gif
    de Valois, Feb 16, 2004
    #14
  15. > >
    > >I'll be flying out of the US and want to store my Oly 5050 digicam inside
    > >it's UW housing to save space. It'll travel in my carry-on bag (I never
    > >check stuff). There's no good way to put the camera in without sealing

    the
    > >housing. I know the housing is good to 130 feet of positive pressure,

    but I
    > >wonder if there is any danger of the slight negative pressure in the

    cabin
    > >damaging any of the seals on the housing? My old Pelican cases had purge
    > >values to deal with this issue, but the Oly housing doesn't.
    > >
    > >Thoughts?
    > >

    >


    This is all kind of irrelevant isn't it? How could there be negative
    pressure in the cabin? If there is, it probably means that there's been a
    serious disaster and you're probably going to crash anyway. Planes always
    maintain pressure in the cabin, it's handy to stop people from passing out
    etc.
    Eugene O'Brien, Feb 16, 2004
    #15
  16. "Eric" <> pounded away at his keyboard resulting in:
    : Interesting question. On my trips, I pack the housing with the door
    :eek:pen with clothes packed around it to keep it from getting damaged. The
    :suggestion that others have made to remove the main O-ring sounds like an
    :even better idea however.

    Sounds pretty labour intensive to me. I use the leave the housing
    open.

    Dan Bracuk
    If at first you don't succeed, you run the risk of failure.
    The Best of rec.scuba http://www.pathcom.com/~bracuk/RecScuba/


    -----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
    http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
    -----== Over 100,000 Newsgroups - 19 Different Servers! =-----
    Dan Bracuk, CTHD, Feb 16, 2004
    #16
  17. "Mark M" <> pounded away at his keyboard
    resulting in:
    :I would think that problem would exist ONLY if you open it at altitude.
    :If you close it on the ground...and don't open it until you're again on the
    :ground, the pressure inside shouldn't change, should it?

    My observations refute your theory. I don't know if the pressure
    changes, but I know that it took me two trips to learn that if I
    closing the housing, it is hard to open when I arrive at my
    destination.

    Dan Bracuk
    If at first you don't succeed, you run the risk of failure.
    The Best of rec.scuba http://www.pathcom.com/~bracuk/RecScuba/


    -----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
    http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
    -----== Over 100,000 Newsgroups - 19 Different Servers! =-----
    Dan Bracuk, CTHD, Feb 16, 2004
    #17
  18. "Tom Thackrey" <> pounded away at his keyboard
    resulting in:
    :It depends on where you land. Think LA to Denver.

    No it doesn't. Mine was hard to open after flying Toronto to Cozumel.

    Dan Bracuk
    If at first you don't succeed, you run the risk of failure.
    The Best of rec.scuba http://www.pathcom.com/~bracuk/RecScuba/


    -----= Posted via Newsfeeds.Com, Uncensored Usenet News =-----
    http://www.newsfeeds.com - The #1 Newsgroup Service in the World!
    -----== Over 100,000 Newsgroups - 19 Different Servers! =-----
    Dan Bracuk, CTHD, Feb 16, 2004
    #18
  19. Dave

    Rich Lockyer Guest

    On Mon, 16 Feb 2004 03:07:20 -0800, "Mark M"
    <> wrote:

    >
    >"Alan Street" <alan@nonono_irsi.com> wrote in message
    >news:150220041455314758%
    >> You won't damage the o-rings or seals, but you will almost certainly
    >> have problems opening the housing after you land (which is why Pelican
    >> cases have vent valves). Remove the main o-ring before you fly.
    >>
    >> Alan

    >
    >I would think that problem would exist ONLY if you open it at altitude.
    >If you close it on the ground...and don't open it until you're again on the
    >ground, the pressure inside shouldn't change, should it?
    >


    The housings are designed to keep pressure out, not keep pressure IN.
    Taking such a housing to altitude will cause it to vent slightly, and
    it doesn't take much "slight" to make it impossible to open.
    When I fly with my Pelican, the lid is ALWAYS compressed and it is
    impossible to open until I release the vent.


    --- Rich
    http://richlockyer.tripod.com/
    Rich Lockyer, Feb 17, 2004
    #19
  20. Dave

    Rich Lockyer Guest

    On Tue, 17 Feb 2004 09:36:37 +1100, "Eugene O'Brien"
    <> wrote:

    >This is all kind of irrelevant isn't it? How could there be negative
    >pressure in the cabin? If there is, it probably means that there's been a
    >serious disaster and you're probably going to crash anyway. Planes always
    >maintain pressure in the cabin, it's handy to stop people from passing out
    >etc.
    >


    Only to 6,000 to 8,000ft, and only really guaranteed to 10,000ft
    Go ahead.... take a bottle of suntan lotion from sea level to 10,000ft
    and open it up.

    There is a significant pressure difference, and it doesn't take much
    to render a housing impossible to open.



    --- Rich
    http://richlockyer.tripod.com/
    Rich Lockyer, Feb 17, 2004
    #20
    1. Advertising

Want to reply to this thread or ask your own question?

It takes just 2 minutes to sign up (and it's free!). Just click the sign up button to choose a username and then you can ask your own questions on the forum.
Similar Threads
  1. Nottoman

    Promise controller needs pressure to work ??

    Nottoman, Jan 4, 2004, in forum: Computer Support
    Replies:
    5
    Views:
    540
    tommyhawk
    Jan 4, 2004
  2. Robert11
    Replies:
    1
    Views:
    6,051
    Old Gringo
    May 25, 2005
  3. =?Utf-8?B?TW9udHJlYWwgTUNTQQ==?=

    Pressure works sometimes!

    =?Utf-8?B?TW9udHJlYWwgTUNTQQ==?=, Jul 13, 2006, in forum: Microsoft Certification
    Replies:
    0
    Views:
    415
    =?Utf-8?B?TW9udHJlYWwgTUNTQQ==?=
    Jul 13, 2006
  4. Pressure on filter with soft brush

    , Jul 13, 2005, in forum: Digital Photography
    Replies:
    5
    Views:
    263
  5. Charles Schuler

    Lower your blood pressure

    Charles Schuler, Feb 23, 2007, in forum: Digital Photography
    Replies:
    0
    Views:
    297
    Charles Schuler
    Feb 23, 2007
Loading...

Share This Page