[PSUBS-MAILIST] Altimeter / barometer/ inclinometer

Wed Apr 22 14:23:33 EDT 2020

A change in cabin pressure doesn't necessarily imply a change in oxygen fraction. Once the hatch is closed, any change in air temperature within the cabin will cause a pressure difference, as will any gas leaks into the cabin from air or oxygen bottles or plumbing, any change to the humidity of the cabin air (water vapour partial pressure), any biogenic gas releases from occupants, and any change to the internal volume of the cabin as a result of thermal contraction / expansion or deflection from external pressure.

That's not to say that the altimeter is not a useful indicator. Certainly, the above sources generally result in small changes in comparison to oxygen consumption, but the simple fact that it is possible that the above sources can result in accumulated error means that confirmation of cabin oxygen level needs to come from another instrument that measures oxygen directly.

Sean

-------- Original Message --------
On Apr. 22, 2020, 11:17, Rick Patton via Personal_Submersibles wrote:

> Hi Hank
> Love your you tube videos.  I was wondering though what the altimeter would read in altitude vs like a reading of 19% when you are trying to keep it at say 21% or there abouts?
> Rick
>
> On Wed, Apr 22, 2020 at 7:03 AM hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>
>> Hi Rick. Yes that is how I operate all the time.  The altitude change indicates if your O2 flow is correct
>> Hank
>>
>> Sent from my iPhone
>>
>>> On Apr 22, 2020, at 10:16 AM, Rick Patton via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>
>>> 
>>> Has anyone used an 02 gas chronograph/ 02 meter, as well as an altimeter in their sub to note the readings in both to see what they both read at the same time? Altitude vs PP02?
>>> Rick
>>>
>>> On Wed, Apr 22, 2020 at 2:04 AM hank pronk via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>>
>>>> David, I have a similar set up in E3000.  I have two not so fancy altimeters.  One is redundant.  I don't see why it matters what the pressure is.  The instrument is there to tell you if the pressure is increasing or decreasing.  It does look more cool though with psi on it.  Mine are mounted to the hull with magnets (Brian got me hooked on magnets)  so I rotate the face to zero then rotate the altimeter so the needle is pointing strait up.  This makes it real obvious when there is a pressure change.
>>>> Hank
>>>>
>>>> On Tuesday, April 21, 2020, 11:32:07 PM MDT, David Colombo via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>>>
>>>> Hi Tim, thats what intrigued me about this unit. Not to mention it had the inclinometer also. The thing I have been thinking is how to set psi chart and to use the rotating dial to set the altitude.
>>>> David
>>>>
>>>> On Tue, Apr 21, 2020, 7:17 PM T Novak via Personal_Submersibles <personal_submersibles at psubs.org> wrote:
>>>>
>>>>> David,
>>>>>
>>>>> Do you plan to just zero the altimeter just prior to hatch closing? Makes sense.
>>>>>
>>>>> Tim
>>>>>
>>>>> From: Personal_Submersibles [mailto:personal_submersibles-bounces at psubs.org] On Behalf Of David Colombo via Personal_Submersibles
>>>>> Sent: Tuesday, April 21, 2020 4:04 PM
>>>>> To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
>>>>> Subject: [PSUBS-MAILIST] Altimeter / barometer/ inclinometer
>>>>>
>>>>> Hi guys, just got my altimeter for the SeaQuestor, which has a built in inclinometer. The dial face can rotate for altitude variance for diving at sea level or lake tahoe(elev 6225ft). The dial face can be set to determine if the barometric pressure is rising or falling. I am thinking to add Alex Smyth's label to be located between the altitude  and the orange  dial. Any thoughts about this?
>>>>>
>>>>> David.
>>>>>
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