<html><head><meta http-equiv="content-type" content="text/html; charset=us-ascii"></head><body dir="auto"><div><span></span></div><div><div style="color:#000; background-color:#fff; font-family:Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px"><div id="yui_3_16_0_ym19_1_1505530250025_2662"><span>Hank got me thinking about compensators again.</span></div><div id="yui_3_16_0_ym19_1_1505530250025_2660"><span id="yui_3_16_0_ym19_1_1505530250025_2659">I had made an initial design for a compensator, using a spring</span></div><div id="yui_3_16_0_ym19_1_1505530250025_2679" dir="ltr"><span id="yui_3_16_0_ym19_1_1505530250025_2680">to produce over-pressure. This design is pretty standard in operation,</span></div><div id="yui_3_16_0_ym19_1_1505530250025_2691" dir="ltr"><span id="yui_3_16_0_ym19_1_1505530250025_2692">with lots of variations.</span></div><div id="yui_3_16_0_ym19_1_1505530250025_2835" dir="ltr"><span id="yui_3_16_0_ym19_1_1505530250025_2834">One problem with the spring is that it might be producing 8 pounds of</span></div><div id="yui_3_16_0_ym19_1_1505530250025_2742" dir="ltr"><span id="yui_3_16_0_ym19_1_1505530250025_2741">force at the start, but as the oil level goes down & the spring extends,</span></div><div id="yui_3_16_0_ym19_1_1505530250025_2740" dir="ltr"><span id="yui_3_16_0_ym19_1_1505530250025_2739">the over-pressure is reduced. Some of the springs I have seen are</span></div><div id="yui_3_16_0_ym19_1_1505530250025_2756" dir="ltr"><span id="yui_3_16_0_ym19_1_1505530250025_2755">pretty large, possibly in an effort to keep the pressure range in a narrower</span></div><div id="yui_3_16_0_ym19_1_1505530250025_2757" dir="ltr"><span>band. 4-5 psi seems a normal over-pressure.</span></div><div id="yui_3_16_0_ym19_1_1505530250025_2738" dir="ltr"><span id="yui_3_16_0_ym19_1_1505530250025_2737">If I replaced the spring with a cylindrical 5lb weight, I would get the same</span></div><div id="yui_3_16_0_ym19_1_1505530250025_2782" dir="ltr"><span id="yui_3_16_0_ym19_1_1505530250025_2781">4lb (weight in water) over-pressure throughout the range of the diaphragms </span></div><div id="yui_3_16_0_ym19_1_1505530250025_2847" dir="ltr"><span id="yui_3_16_0_ym19_1_1505530250025_2846">travel. </span></div><div id="yui_3_16_0_ym19_1_1505530250025_2879" dir="ltr"><span id="yui_3_16_0_ym19_1_1505530250025_2878">Can anyone see a problem with this? Any comments. The lead may bounce </span></div><div id="yui_3_16_0_ym19_1_1505530250025_2879" dir="ltr"><span>around a bit</span></div><div dir="ltr"><span>during transport but I don't think this would be a problem. </span></div><div id="yui_3_16_0_ym19_1_1505530250025_2880" dir="ltr"><span id="yui_3_16_0_ym19_1_1505530250025_2920">My initial design is attached!</span></div><div id="yui_3_16_0_ym19_1_1505530250025_2921" dir="ltr"><span>Alan</span></div><div id="yui_3_16_0_ym19_1_1505530250025_2912" dir="ltr"><span><br></span></div><div class="qtdSeparateBR" id="yui_3_16_0_ym19_1_1505530250025_2658"><br><br></div><div class="yahoo_quoted" id="yui_3_16_0_ym19_1_1505530250025_2588" style="display: block;"> <div id="yui_3_16_0_ym19_1_1505530250025_2587" style="font-family: Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;"> <div id="yui_3_16_0_ym19_1_1505530250025_2586" style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;"> <div id="yui_3_16_0_ym19_1_1505530250025_2585" dir="ltr"> <font id="yui_3_16_0_ym19_1_1505530250025_2584" face="Arial" size="2"> <hr size="1" id="yui_3_16_0_ym19_1_1505530250025_2661"> <b><span style="font-weight: bold;">From:</span></b> hank pronk via Personal_Submersibles <<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>><br> <b><span style="font-weight: bold;">To:</span></b> Personal Submersibles General Discussion <<a href="mailto:personal_submersibles@psubs.org">personal_submersibles@psubs.org</a>> <br> <b><span style="font-weight: bold;">Sent:</span></b> Thursday, September 14, 2017 12:37 PM<br> <b><span style="font-weight: bold;">Subject:</span></b> [PSUBS-MAILIST] oil compensation<br> </font> </div> <div class="y_msg_container" id="yui_3_16_0_ym19_1_1505530250025_2913"><br><div id="yiv7923422751"><div id="yui_3_16_0_ym19_1_1505530250025_2924"><div id="yui_3_16_0_ym19_1_1505530250025_2923" style="font-family: Helvetica Neue, Helvetica, Arial, sans-serif; font-size: 13px;"><div>Hi All,</div><div id="yui_3_16_0_ym19_1_1505530250025_3049">Thank you Greg, just sent them a request.</div><div><br></div><div id="yui_3_16_0_ym19_1_1505530250025_2922">I have tested my air cylinder compensator for my thrusters both in the pressure test and a couple days ago to 100 feet. The set up seems to work with no water intrusion into the motors. I have the cylinder mounted below the motors witch causes a small air pocket in the hydraulic fitting on top of the motor. I am not worried about the small amount of air except the potential of oil being forced up past the air pocket. This makes me think the compensating cylinder should be above the motors. Then I wonder why does the compensating cylinder need oil in it at all. As long as the bore in the cylinder has enough volume so the piston is not bottomed out at max depth. I also have a small spring pushing the cylinder rod to create a small internal pressure above ambient. Is my logic flawed? it would be very convenient to eliminate the oil in the cylinder and would make the compensator faster to react to pressure change say in a fast ascent. </div><div id="yui_3_16_0_ym19_1_1505530250025_3053">Hank</div></div></div></div>_______________________________________________<br>Personal_Submersibles mailing list<br><a href="mailto:Personal_Submersibles@psubs.org" ymailto="mailto:Personal_Submersibles@psubs.org">Personal_Submersibles@psubs.org</a><br><a href="http://www..psubs.org/mailman/listinfo.cgi/personal_submersibles" target="_blank">http://www.psubs.org/mailman/listinfo.cgi/personal_submersibles</a><br><br><br></div> </div> </div> </div></div></div><div><img src="cid:6591c9f9-e32c-ae3a-7c13-ba5c9e7921ae@yahoo.com" id="6591c9f9-e32c-ae3a-7c13-ba5c9e7921ae@yahoo.com" style="padding:0px 1px 1px 0px;"></div></body></html>