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--></style></head><body bgcolor="white" lang="EN-NZ" link="blue" vlink="purple"><p dir="ltr">Such an accumulator sounds like it might be ideal for oil filled volume pressure compensation (i.e. 3-7 psi above ambient) if mounted external to the vessel. Do you have a link? Unfortunately, 3-7 psi isn't much help in a hydraulic power application.</p>
<p dir="ltr">Sean</p>
<br><br><div class="gmail_quote">On November 27, 2016 12:29:50 PM MST, Hugh Fulton via Personal_Submersibles <personal_submersibles@psubs.org> wrote:<blockquote class="gmail_quote" style="margin: 0pt 0pt 0pt 0.8ex; border-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;">
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</o:shapelayout></xml><![endif]--><div class="WordSection1"><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">We have done an accumulator with Carbon fibre cylinder used in the pneumatics industry which is designed for O’rings on pistons. 6” ID x 10 “ long and a spring providing 3-7 psi (empty to full) compensating pressure. It has a 6” stroke and the piston rod has a magnet in the end and a magnetic switch to tell when it is nearly empty. Hugh <p></p></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><p> </p></span></p><div><div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm"><p class="MsoNormal"><b><span lang="EN-US" style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext">From:</span></b><span lang="EN-US"
style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext"> Personal_Submersibles [mailto:personal_submersibles-bounces@psubs.org] <b>On Behalf Of </b>Sean T. Stevenson via Personal_Submersibles<br /><b>Sent:</b> Monday, 28 November 2016 5:28 AM<br /><b>To:</b> Personal Submersibles General Discussion<br /><b>Subject:</b> Re: [PSUBS-MAILIST] Hydraulic idea<p></p></span></p></div></div><p class="MsoNormal"></p><p> </p><div><p class="MsoNormal">The commercial accumulators are heavy because they are designed for high service pressures. If you know for a fact that your vessels will only ever see e.g. 1100 psi, you can get away with something lighter. The concept is exactly the same. Pistons require tight tolerances and surface finishes - the bladder is the easier solution. Since the bladder will never see any delta-P across it (disregarding it's own elasticity), it doesn't need to be that substantial - even an inner tube might work.
Just something to allow you to completely purge all air out of the oil volume, and which is materially compatible with the oil, and which will maximally expand within the pressure vessel.<br /><br />As an alternative to your constant pressure accumulator, you could go with a sealed accumulator and a small hydraulic pump which is capable of high pressures but not necessarily high flow rates. For example, empty the accumulator of oil, and precharge the bladder to 1000 psi. This ensures that just before going completely empty, it would still be supplying fluid at 1000 psi. If you do this, you can use a pressure gauge on the gas side of the accumulator to monitor the oil level, so you pump oil in until the gauge reads 3000 psi, and you then know the vessel is 2/3 full of oil. You can recharge the accumulator over time at a much lesser flow rate than is actually demanded by the manipulator, because the accumulator supplies the high flow necessary for operation.<br
/><br />Sean<br /><br /><br />On 2016-11-27 08:44, hank pronk via Personal_Submersibles wrote:</p><p></p></div><blockquote style="margin-top:5.0pt;margin-bottom:5.0pt"><div><div id="yui_3_16_0_1_1480260351346_4982"><p class="MsoNormal" style="background:white"><span style="font-size:9.0pt;font-family:helveticaneue">Sean,<p></p></span></p></div><div id="yui_3_16_0_1_1480260351346_4982"><p class="MsoNormal" style="background:white"><span style="font-size:9.0pt;font-family:helveticaneue">I agree completely except the operating pressure is not as high as you suggest. I know for a fact Gamma ran at 1,100 psi from the maintenance records. You do make a point that I missed. Without a bladder, I could leak oil into the water when relieving the pressure while surfacing. I was considering an accumulator either a piston or rubber bladder type, but they are very heavy. I would like to figure out how to use this idea with a water pressure tank
with bladder for the light weight. <p></p></span></p></div><div id="yui_3_16_0_1_1480260351346_4982"><p class="MsoNormal" style="background:white"><span style="font-size:9.0pt;font-family:helveticaneue">Maybe this is not the way to go, but an interesting brain exercise. <p></p></span></p></div><div id="yui_3_16_0_1_1480260351346_4982"><p class="MsoNormal" style="background:white"><span style="font-size:9.0pt;font-family:helveticaneue">I do have a small hyd pump that is pretty light and makes 1,100 ps,i it is just such a pain in the butt. Mind you with external batteries and external pump it will not be as bad.<p></p></span></p></div><div><p class="MsoNormal" style="margin-bottom:12.0pt;background:white"><span style="font-size:9.0pt;font-family:helveticaneue"><p> </p></span></p></div><div><div><div><div><p class="MsoNormal" style="background:white"><span style="font-size:10.0pt;font-family:"Arial","sans-serif"">On Sunday, November 27, 2016 7:38 AM, Sean
T. Stevenson via Personal_Submersibles <a href="mailto:personal_submersibles@psubs.org"><personal_submersibles</a></span></p></div></div></div></div></div></blockquote></div></blockquote></div></body></html>