[PSUBS-MAILIST] Life support

Wed Apr 23 18:44:56 EDT 2014

>From what I recall I believe it was 20kg for 2 people which is close.  However I need to test.  Hugh

From: Personal_Submersibles [mailto:personal_submersibles-bounces at psubs.org] On Behalf Of via Personal_Submersibles
Sent: Thursday, 24 April 2014 2:03 a.m.
To: Personal Submersibles General Discussion
Subject: Re: [PSUBS-MAILIST] Life support

No problem Sean,

I  believe my amount it right, it just didn't look consistent with the rest of psubs, but just based on the little amounts of O2 that a lot of psubbers are carrying, I don't believe most are carrying enough sodasorb either. I came up with 23lbs per person (46 lbs total).

Thanks,

Scott Waters

-------- Original Message --------
Subject: Re: [PSUBS-MAILIST] Life support
From: "Sean T. Stevenson via Personal_Submersibles"
<personal_submersibles at psubs.org>
Date: Wed, April 23, 2014 6:48 am
To: Personal Submersibles General Discussion
<personal_submersibles at psubs.org>

I'm sorry - I was short on time last night or I would have addressed the scrubbing as well. The design expected CO2 production rate is set by the rules in a similar manner. You need to look at the data sheet of your chosen scrubber media to find it's scrubbing capacity, efficiency, etc., then size the media volume accordingly (mission duration + 72 hours), and make sure that the flow path, flow rate / dwell time and so forth are sufficient to meet the rated capacity.  Also, you might want to separate mission and emergency scrubbers to conserve media.

Sean

On April 23, 2014 7:02:00 AM MDT, via Personal_Submersibles <personal_submersibles at psubs.org> wrote: 

Sean,

Seems like your results on O2 are the same that I found. I have (2) 80 cubic foot O2 tanks on my 2 man submarine. I am pretty sure most psubbers are not sticking to the mission time plus 72 hour requirement. I believe my figuring of 23 lbs of intersorb 812 per person is also close to correct and most psubbers are not carrying that as well. It seemed like a lot to me at the beginning based on my observations of other psubs, but I think it is correct.

Thanks,

Scott Waters

-------- Original Message --------
Subject: Re: [PSUBS-MAILIST] Life support
From: "Sean T. Stevenson via Personal_Submersibles"
<personal_submersibles at psubs.org>
Date: Tue, April 22, 2014 8:13 pm
To: Personal Submersibles General Discussion
<personal_submersibles at psubs.org>

According to the ABS rules, per (11/35.3), you need sufficient oxygen for the mission duration PLUS the 72 hour reserve.

Per (8/7.1), oxygen:  0.038 kg (0.084 lb) per hour, per person, at 1 atm.

x 72 hours emergency duration = 2.736 kg (6.032 lb) per person for 72 hours.

2.736 kg x (1000g/kg) x (mol O2/31.9988g O2) x (22.4 liters / mol O2) = 1915 liters (@ STP, ideal gas assumptions)

= 68 cubic feet oxygen per person for emergency reserve, additional oxygen appropriate to mission duration.

Sean

On 2014-04-22 17:52, swaters via Personal_Submersibles wrote:

I have been trying to make sure I have suffecent life support for 72 hours per ABS. It seems like the research varys a little. 

I am showing

*80 cubic feet of O2 per person

*23 lbs sodasorb per person

Is this right?

Thanks,

Scott Waters

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