[PSUBS-MAILIST] K350 motors and housings - available

Tue Apr 2 21:29:48 EDT 2019

Brian,
Have radio ( many actually), but no antenna up yet. Have had other things occupying my time and have to use a stealth unit due to restrictions. Guess I should build that DDRR antenna for HF.
73
Keith T.
-------- Original message --------From: Brian Cox via Personal_Submersibles <personal_submersibles at psubs.org> Date: 4/2/19  3:34 PM  (GMT-08:00) To: Personal Submersibles General Discussion <personal_submersibles at psubs.org> Subject: Re: [PSUBS-MAILIST] K350 motors and housings - available 
Keith  (k6fee)   Do you have a Ham radio yet ?
Brian kk6irc 

--- personal_submersibles at psubs.org wrote:

From: k6fee via Personal_Submersibles <personal_submersibles at psubs.org>
To: Personal Submersibles General Discussion <personal_submersibles at psubs.org>
Subject: Re: [PSUBS-MAILIST] K350 motors and housings - available
Date: Tue, 02 Apr 2019 15:00:50 -0700

INMHO the only safe way to use a HFC cooler is to have the unit in a sealed box under vacuum, chilling water that is pumped to fan coils. If there is a leak, an alarm ( pressure & HFC detector activated) informs the operator so they can surface, while the sealed unit contains the refrigerant protecting the occupants.
Keith T.
The problem with refrigerants in confined spaces, and this is true both of HFC-134a and the environmentally friendly(er) alternatives, such as HFO-1234yf, is that they release extremely toxic decomposition products in the event of fire. Of course, any fire is going to compromise your atmosphere, so this may be a moot point, but it's something to consider. HFC-134a has low acute toxicity, but is not strictly a simple inert asphyxiant. A 1 hour EEGL exposure limit recommendation that I managed to find for HFC-134a is 4,000 ppm.

In a 72 cu. ft. volume, assuming a starting FO2 of 20.9%, you could add a full 7 cu. ft. of simple asphyxiant gas before the cabin FO2 dropped to 19%. Death likely wouldn't occur due to hypoxia above 16% FO2, but you won't be accomplishing much with oxygen that low. 19.0% to 19.5% are typical occupational limits for oxygen deficient atmospheres.

That said, hypoxia is not the only risk as I pointed out. I would consider the health effects from inhalation exposure and keep to recommended exposure limits. For maximum safety, I might be inclined to separate refrigerants from occupied spaces by means of a water / propylene glycol heat exchanger circuit, but of course this will affect your energy budgets.

Sean

-------- Original Message --------
On Apr 2, 2019, 11:49, Cliff Redus via Personal_Submersibles < personal_submersibles at psubs.org> wrote:
-------- Original message --------From: "Sean T. Stevenson via Personal_Submersibles" <personal_submersibles at psubs.org> Date: 4/2/19  11:33 AM  (GMT-08:00) To: personal_submersibles at psubs.org Subject: Re: [PSUBS-MAILIST] K350 motors and housings - available 

        Keith, I like the idea of a DIY AC system for my boat but hate the idea of dying because of a refrigerant leak.  I looked up the MSDS sheet for HFC-134a (common refrigant used in auto AC systems)     ImageViewer  Seems like it is classified as a Simple Asphyxian which according to Wikipidia "An asphyxiant gas is a nontoxic or minimally toxic gas which reduces or displaces the normal oxygen concentration in breathing air. "
ImageViewer

What this mean to me is that we would to do a calc to see what the oxygen concentration in a 1-atm boat would go to if all the HFC-134a in the unit was released at one time to see if the concentration would result in hypoxia for the operator.  In my boat I measure O2 concentration as I have a PID controller tasked with keeping the O2 concentration at 21%  So I would get a low O2 alarm rather quickly.

Sean, you are a technical diver, do you think there would be an issue with hypoxia if all the HFC-134a in a small AC unit were dumped into a one atm cabin say 72 cuft?
Cliff

                    On Tuesday, April 2, 2019, 11:46:05 AM CDT, k6fee via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

                The DC compressor & water cooled condenser are the most expensive items.
If your a DIY'er, go to your nearest "Pick & Pull" get a car AC compressor add a DC drive motor, condenser & evap coil and roll your own.  It will take 2 HP to full drive the compressor, however you can vary the speed and control the cooling, while minimizing current drain. You'll need a refrigerant detector as a leak will kill you in the confines of a PSUB. Or go thermo electric.
Keith T.
-------- Original message --------From: Cliff Redus via Personal_Submersibles <personal_submersibles at psubs.org> Date: 4/2/19  8:40 AM  (GMT-08:00) To: k6fee via Personal_Submersibles <personal_submersibles at psubs.org> Subject: Re: [PSUBS-MAILIST] K350 motors and housings - available 

        Thanks for the links,  The MES24S - 24V unit looks like it would work great but at  $3,895 , I am not going to be ordering in the near future. In the spirit of Psub and DIY, I wonder how hard it would be to design and build on of these units.  Seems to be made up of readily available parts like a compressor, blower, coil ....
Cliff

                    On Tuesday, April 2, 2019, 9:46:03 AM CDT, k6fee via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

                Allen,
Check these out.
http://www.cruisencomfortusa.com/marineseries/?gclid=EAIaIQobChMIirDF5s6x4QIVcyCtBh3K8w2JEAMYASADEgIDqvD_BwE
http://www.comar-marine.com/product.php?id_product=20
Keith T.
-------- Original message --------From: Cliff Redus via Personal_Submersibles <personal_submersibles at psubs.org> Date: 4/2/19  7:06 AM  (GMT-08:00) To: Brian Hughes via Personal_Submersibles <personal_submersibles at psubs.org> Subject: Re: [PSUBS-MAILIST] K350 motors and housings - available 

        To me AC on personal subs is an interesting topic.  As the Psub community frequently dives off Islamorada Florida, it is a relative thread.Below is a graph taken from flight recorder on the R300 during a Psub dive off the coast of Islamorada in August of 2017.
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