<html><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8"></head><body>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.<div><br></div><div>Keith T.</div><div><br></div>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.<br><br>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.<br><br>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.<br><br>Sean<br><br><br>-------- Original Message --------<br>On Apr 2, 2019, 11:49, Cliff Redus via Personal_Submersibles < personal_submersibles@psubs.org> wrote:<blockquote class="protonmail_quote"><br><!--[if gte mso 9]><xml><o:OfficeDocumentSettings><o:AllowPNG/><o:PixelsPerInch>96</o:PixelsPerInch></o:OfficeDocumentSettings></xml><![endif]--><div style="font-size:100%;color:#000000"><!-- originalMessage --><div>-------- Original message --------</div><div>From: "Sean T. Stevenson via Personal_Submersibles" <personal_submersibles@psubs.org> </div><div>Date: 4/2/19 11:33 AM (GMT-08:00) </div><div>To: personal_submersibles@psubs.org </div><div>Subject: Re: [PSUBS-MAILIST] K350 motors and housings - available </div><div><br></div></div><div class="ydpd9591711yahoo-style-wrap" style=""><div id="ydpd9591711yiv9550314869" style=""><div class="ydpd9591711yiv9550314869ydp24017b51yahoo-style-wrap" style=""><div style="font-family: times new roman, new york, times, serif; font-size: 16px;"></div>
<div style="font-family: times new roman, new york, times, serif; font-size: 16px;">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) <a shape="rect" class="ydpd9591711yiv9550314869enhancr_card_5128173108" href="https://3eonline.com/ImageServer/ImageViewer.aspx?id=3Q%2FfAR8ne%2FvPh6syVnSymkS%2BBDo8OjmbVocxRCMEgeG%2Fk%2B6G7BpCwxJIcm%2FtzFJTddB5zxzJXIW7nbmF5mKrdg%3D%3D" style="font-family:times new roman, new york, times, serif;font-size:16px;" rel="nofollow" target="_blank">ImageViewer</a> Seems like it is classified as a <span style="font-family:times new roman, new york, times, serif;font-size:16px;">Simple Asphyxian which according to Wikipidia "<span><span style="color:rgb(34, 34, 34);font-family:sans-serif;font-size:10.5px;">An </span><b style="color:rgb(34, 34, 34);font-family:sans-serif;font-size:10.5px;">asphyxiant gas</b><span style="color:rgb(34, 34, 34);font-family:sans-serif;font-size:10.5px;"> is a nontoxic or minimally toxic </span><a shape="rect" href="https://en.wikipedia.org/wiki/Gas" title="Gas" style="color:rgb(11, 0, 128);background-image:none;font-family:sans-serif;font-size:10.5px;" rel="nofollow" target="_blank">gas</a><span style="color:rgb(34, 34, 34);font-family:sans-serif;font-size:10.5px;"> which reduces or displaces the normal </span><a shape="rect" href="https://en.wikipedia.org/wiki/Oxygen" title="Oxygen" style="color:rgb(11, 0, 128);background-image:none;font-family:sans-serif;font-size:10.5px;" rel="nofollow" target="_blank">oxygen</a><span style="color:rgb(34, 34, 34);font-family:sans-serif;font-size:10.5px;"> concentration in breathing </span><a shape="rect" href="https://en.wikipedia.org/wiki/Gas_composition" title="Gas composition" style="color:rgb(11, 0, 128);background-image:none;font-family:sans-serif;font-size:10.5px;" rel="nofollow" target="_blank">air</a><span style="color:rgb(34, 34, 34);font-family:sans-serif;font-size:10.5px;">. "</span></span></span></div><div style="font-family: times new roman, new york, times, serif; font-size: 16px;"><br clear="none"></div><div class="ydpd9591711yiv9550314869ydpadcff8a6yahoo-link-enhancr-card ydpd9591711yiv9550314869ydpadcff8a6yahoo-link-enhancr-not-allow-cover ydpd9591711yiv9550314869ydpadcff8a6ymail-preserve-class ydpd9591711yiv9550314869ydpadcff8a6ymail-preserve-style" id="ydpd9591711yiv9550314869ydpadcff8a6enhancr_card_5128173108" style="font-family: Helvetica Neue, Segoe UI, Helvetica, Arial, sans-serif; font-size: 16px; max-width: 400px;" data-url="https://3eonline.com/ImageServer/ImageViewer.aspx?id=3Q%2FfAR8ne%2FvPh6syVnSymkS%2BBDo8OjmbVocxRCMEgeG%2Fk%2B6G7BpCwxJIcm%2FtzFJTddB5zxzJXIW7nbmF5mKrdg%3D%3D" data-type="YENHANCER" data-size="MEDIUM" contenteditable="false"><a shape="rect" class="ydpd9591711yiv9550314869ydpadcff8a6yahoo-enhancr-cardlink" href="https://3eonline.com/ImageServer/ImageViewer.aspx?id=3Q%2FfAR8ne%2FvPh6syVnSymkS%2BBDo8OjmbVocxRCMEgeG%2Fk%2B6G7BpCwxJIcm%2FtzFJTddB5zxzJXIW7nbmF5mKrdg%3D%3D" style="text-decoration:none !important;color:#000 !important;" rel="nofollow" target="_blank"><table class="ydpd9591711yiv9550314869ydpadcff8a6card-wrapper ydpd9591711yiv9550314869ydpadcff8a6yahoo-ignore-table" border="0" cellpadding="0" cellspacing="0" style="max-width:400px;"><tbody><tr><td colspan="1" rowspan="1" width="400"><table class="ydpd9591711yiv9550314869ydpadcff8a6card ydpd9591711yiv9550314869ydpadcff8a6yahoo-ignore-table" border="0" cellpadding="0" cellspacing="0" width="100%" style="max-width:400px;border-width:1px;border-style:solid;border-color:rgb(224, 228, 233);border-radius:2px;"><tbody><tr><td colspan="1" rowspan="1"><table class="ydpd9591711yiv9550314869ydpadcff8a6card-info ydpd9591711yiv9550314869ydpadcff8a6yahoo-ignore-table" border="0" cellpadding="0" cellspacing="0" style="background:#fff;position:relative;z-index:2;width:100%;max-width:400px;border-radius:0 0 2px 2px;border-top:1px solid rgb(224, 228, 233);"><tbody><tr><td colspan="1" rowspan="1" style="background-color:#ffffff;padding:16px 0 16px 12px;vertical-align:top;border-radius:0 0 0 2px;"></td><td colspan="1" rowspan="1" style="vertical-align:middle;padding:12px 24px 16px 12px;width:99%;font-family:Helvetica Neue, Segoe UI, Helvetica, Arial, sans-serif;border-radius:0 0 2px 0;"><h2 class="ydpd9591711yiv9550314869ydpadcff8a6card-title" style="font-size:14px;line-height:19px;margin:0px 0px 6px;font-family:Helvetica Neue, Segoe UI, Helvetica, Arial, sans-serif;color:rgb(38, 40, 42);">ImageViewer</h2><p class="ydpd9591711yiv9550314869ydpadcff8a6card-description" style="font-size:12px;line-height:16px;margin:0px;color:rgb(151, 155, 167);"></p></td></tr></tbody></table></td></tr></tbody></table></td></tr></tbody></table></a></div><div style="font-family: times new roman, new york, times, serif; font-size: 16px;"><br clear="none"></div><div style="font-family: times new roman, new york, times, serif; font-size: 16px;"><br clear="none"></div><div style="font-family: times new roman, new york, times, serif; font-size: 16px;"><span><span><span><span style="color:rgb(34, 34, 34);font-family:sans-serif;font-size:10.5px;"><br clear="none"></span></span></span></span></div><div style="font-family: times new roman, new york, times, serif; font-size: 16px;"><span><span><span><span style="color:rgb(34, 34, 34);font-family:sans-serif;font-size:10.5px;"><span><span style="color:rgb(0, 0, 0);font-family:times new roman, new york, times, serif;font-size:16px;">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 <span>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.</span></span></span><br clear="none"></span></span></span></span></div><div style="font-family: times new roman, new york, times, serif; font-size: 16px;"><br></div><div style="">Sean, you are a technical diver, do you think there would be an issue with hypoxia if <span style="font-family: times new roman, new york, times, serif; font-size: 16px; color: rgb(0, 0, 0);">all the </span>HFC-134a in a small AC unit were dumped into a one atm cabin say 72 cuft?</div><div style="font-family: times new roman, new york, times, serif; font-size: 16px;"><span><span><span><span style="color:rgb(34, 34, 34);font-family:sans-serif;font-size:10.5px;"><span><span style="color:rgb(0, 0, 0);font-family:times new roman, new york, times, serif;font-size:16px;"><span><br></span></span></span></span></span></span></span></div><div style="font-family: times new roman, new york, times, serif; font-size: 16px;"><span><span><span><span style="color:rgb(34, 34, 34);font-family:sans-serif;font-size:10.5px;"><span><span style="color:rgb(0, 0, 0);font-family:times new roman, new york, times, serif;font-size:16px;"><span>Cliff</span></span></span></span></span></span></span></div><div style="font-family: times new roman, new york, times, serif; font-size: 16px;"><span><span><span><span style="color:rgb(34, 34, 34);font-family:sans-serif;font-size:10.5px;"><br clear="none"></span></span></span></span></div><div style="font-family: times new roman, new york, times, serif; font-size: 16px;"><br clear="none"></div>
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On Tuesday, April 2, 2019, 11:46:05 AM CDT, k6fee via Personal_Submersibles <personal_submersibles@psubs.org> wrote:
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<div><div id="ydpc0557cc8yiv9550314869ydp374cbf89yiv9767036766"><div>The DC compressor & water cooled condenser are the most expensive items.<div><br clear="none"></div><div>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.</div><div><br clear="none"></div><div>Keith T.</div><div><br clear="none"></div><div style="font-size:100%;color:#000000;"><div class="ydpc0557cc8yiv9550314869ydp374cbf89yiv9767036766yqt7051536556" id="ydpc0557cc8yiv9550314869ydp374cbf89yiv9767036766yqtfd23425"><div>-------- Original message --------</div><div>From: Cliff Redus via Personal_Submersibles <personal_submersibles@psubs.org> </div><div>Date: 4/2/19 8:40 AM (GMT-08:00) </div><div>To: k6fee via Personal_Submersibles <personal_submersibles@psubs.org> </div><div>Subject: Re: [PSUBS-MAILIST] K350 motors and housings - available </div><div><br clear="none"></div></div></div><div class="ydpc0557cc8yiv9550314869ydp374cbf89yiv9767036766yqt7051536556" id="ydpc0557cc8yiv9550314869ydp374cbf89yiv9767036766yqtfd98764"><div class="ydpc0557cc8yiv9550314869ydp374cbf89yiv9767036766ydpc198c439yahoo-style-wrap" style="font-family:times new roman, new york, times, serif;font-size:16px;"><div></div>
<div>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 ....</div><div><br clear="none"></div><div>Cliff</div><div><br clear="none"></div>
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On Tuesday, April 2, 2019, 9:46:03 AM CDT, k6fee via Personal_Submersibles <personal_submersibles@psubs.org> wrote:
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<div><div id="ydpc0557cc8yiv9550314869ydp374cbf89yiv9767036766ydpf4ae7d6eyiv3975522288"><div><div>Allen,</div><div><br clear="none"></div><div>Check these out.</div><div><br clear="none"></div>http://www.cruisencomfortusa.com/marineseries/?gclid=EAIaIQobChMIirDF5s6x4QIVcyCtBh3K8w2JEAMYASADEgIDqvD_BwE<div><br clear="none"></div><div>http://www.comar-marine.com/product.php?id_product=20</div><div><br clear="none"></div><div>Keith T.</div><div><br clear="none"></div><div style="font-size:100%;color:#000000;"><div class="ydpc0557cc8yiv9550314869ydp374cbf89yiv9767036766ydpf4ae7d6eyiv3975522288yqt3392438724" id="ydpc0557cc8yiv9550314869ydp374cbf89yiv9767036766ydpf4ae7d6eyiv3975522288yqtfd26820"><div>-------- Original message --------</div><div>From: Cliff Redus via Personal_Submersibles <personal_submersibles@psubs.org> </div><div>Date: 4/2/19 7:06 AM (GMT-08:00) </div><div>To: Brian Hughes via Personal_Submersibles <personal_submersibles@psubs.org> </div><div>Subject: Re: [PSUBS-MAILIST] K350 motors and housings - available </div><div><br clear="none"></div></div></div><div class="ydpc0557cc8yiv9550314869ydp374cbf89yiv9767036766ydpf4ae7d6eyiv3975522288yqt3392438724" id="ydpc0557cc8yiv9550314869ydp374cbf89yiv9767036766ydpf4ae7d6eyiv3975522288yqtfd86137"><div class="ydpc0557cc8yiv9550314869ydp374cbf89yiv9767036766ydpf4ae7d6eyiv3975522288ydp13f774e1yahoo-style-wrap" style="font-family:times new roman, new york, times, serif;font-size:16px;"><div></div>
<div>To me AC on personal subs is an interesting topic. As the Psub community frequently dives off Islamorada Florida, it is a relative thread.</div><div>Below is a graph taken from flight recorder on the R300 during a Psub dive off the coast of <span><span style="color:rgb(0, 0, 0);font-family:times new roman, new york, times, serif;font-size:16px;">Islamorada in August of 2017.</span></span></div><div><br clear="none"></div><div></div></div></div></div></div></div></div></div></div></div></div></div></div></blockquote></body></html>