<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div></div><div>It does need to go above the waterline. On surfacing you push the stem to equalize pressure, and if you did that underwater you'd get some water in the boat. Nothing huge, but definitely a nuisance. How about in the hatch? That's where it's going on Shackleton.</div><div><br></div><div>Best,</div><div><br></div><div>Alec</div><div><br>On Feb 27, 2016, at 9:45 PM, Brian Cox via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>> wrote:<br><br></div><blockquote type="cite"><div><div style="font-family:Arial, sans-serif; font-size:10pt;"><div>Would there be any problem locating that valve below the water line, I don't want have any available ports up high.</div><div> </div><div>Brian<br><br>--- <a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a> wrote:<br><br>From: via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br>To: Personal Submersibles General Discussion <<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br>Subject: Re: [PSUBS-MAILIST] Acceptable cabin pressure swing<br>Date: Sat, 27 Feb 2016 12:18:40 -0600<br><br></div><div>Yes, I thought I gave the number for the stainless steel version. Yes ss is the way to go.</div><div><br></div><div>Thanks for catching this.<br><br><br><div>Cliff Redus</div></div><div><br>On Feb 27, 2016, at 9:40 AM, Alan via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>> wrote:<br><br></div><blockquote><div><div>Cliff,</div><div>that item is carbon steel. I think Brian will be diving in sea water.</div><div>Cheers Alan<br><br>Sent from my iPad</div><div><br>On 28/02/2016, at 4:07 am, Cliff Redus via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>> wrote:<br><br></div><blockquote><div>Brian, see McMaster Carr part number 4620K41. This has a 1 psi cracking pressure, not 0.5 psi that I mentioned earlier.<div><br></div><div>Cliff<br><br>On Thursday, February 25, 2016, Brian Cox via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>> wrote:<br><blockquote style="margin: 0px 0px 0px 0.8ex; padding-left: 1ex; border-left-color: rgb(204, 204, 204); border-left-width: 1px; border-left-style: solid;"><div style="font-family: Arial,sans-serif; font-size: 10pt;"><div>Cliff, Where did you find that 1/2 psi relief valve?</div><div> </div><div>Brian Cox<br><br>--- <a>personal_submersibles@psubs.org</a> wrote:<br><br>From: Cliff Redus via Personal_Submersibles <<a>personal_submersibles@psubs.org</a>><br>To: Personal Submersibles General Discussion <<a>personal_submersibles@psubs.org</a>><br>Subject: Re: [PSUBS-MAILIST] Acceptable cabin pressure swing<br>Date: Thu, 25 Feb 2016 19:05:00 -0600<br><br></div><div dir="ltr"><div>Jon for my boat, I have a pressure relief valve with a 1/2 psi cracking pressure to vent pressure while on the surface. I have a high cabin pressure alarm that triggers at 20 psia (5.3 psig) and a cabin lower pressure alarm set at 12 psia (-2.7 psig). In the PLC I also record and display the cabin pressure at the time the hatch is closed and log all alarm states every second. </div><div><br></div><div>I have never had either a high or low cabin pressure alarm while diving. I have had elevated cabin pressure caused by accidently having the backup manual O2 value open and a leak in an air fitting on anther occasion.</div><div><br></div><div>Cliff</div></div><div><br><div>On Wed, Feb 24, 2016 at 1:12 PM, Jon Wallace via Personal_Submersibles <span dir="ltr"><<a>personal_submersibles@psubs.org</a>></span> wrote:<br><blockquote style="margin: 0px 0px 0px 0.8ex; padding-left: 1ex; border-left-color: rgb(204, 204, 204); border-left-width: 1px; border-left-style: solid;"><br>
I think this is somewhat subjective but what is general consensus on maximum cabin pressure swing (higher/lower) relative to hatch closing at the start of a dive before setting off alarms? My thought is that an alarm should sound well before any point of emergency. I'm considering sounding a warning at 2psi +/- and an alarm at 4psi +/- but I'm not sure if this is too strict.<br>
<br>
Jon<br>
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