<html><head></head><body><div style="color:#000; background-color:#fff; font-family:times new roman, new york, times, serif;font-size:16px"><div id="yui_3_16_0_ym19_1_1491919462422_9761" dir="ltr">I don't think you need to test external pressure. If you maintain 4psi over ambient then all you need to test is whether 4psi is enough to blow past the single seal. You could keep cranking the pressure up within the motor housing to see what the cracking pressure of the seal is. Of course I imagine that will change over time as the shaft and elements wear on the seal. </div><div id="yui_3_16_0_ym19_1_1491919462422_9761" dir="ltr"><br></div><div id="yui_3_16_0_ym19_1_1491919462422_9761" dir="ltr">Jon</div><div id="yui_3_16_0_ym19_1_1491919462422_9761" dir="ltr"><br></div><div class="qtdSeparateBR" id="yui_3_16_0_ym19_1_1491919462422_9760"><br></div><div class="yahoo_quoted" id="yui_3_16_0_ym19_1_1491919462422_9682" style="display: block;"> <div style="font-family: times new roman, new york, times, serif; font-size: 16px;" id="yui_3_16_0_ym19_1_1491919462422_9681"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;" id="yui_3_16_0_ym19_1_1491919462422_9680"> <div dir="ltr" id="yui_3_16_0_ym19_1_1491919462422_9758"><font size="2" face="Arial" id="yui_3_16_0_ym19_1_1491919462422_9759"> On Tuesday, April 11, 2017 8:31 AM, Private via Personal_Submersibles <personal_submersibles@psubs.org> wrote:<br></font></div> <br><br> <div class="y_msg_container" id="yui_3_16_0_ym19_1_1491919462422_9679"><div id="yiv5018521785"><div id="yui_3_16_0_ym19_1_1491919462422_9678"><div></div><div id="yui_3_16_0_ym19_1_1491919462422_9685">My thrusters are air compensated with the compensation pressure being adjustable and the system monitored via a differential pressure gauge in the sub. I could easily crank up the compensation pressure to test if air escapes a single unreversed seal (although I agree it makes sense to reverse it). But I don't have an easy way to test external pressure if that's what you meant.</div><div id="yui_3_16_0_ym19_1_1491919462422_9684"><br clear="none"></div><div id="yui_3_16_0_ym19_1_1491919462422_9677">Thanks,</div><div id="yui_3_16_0_ym19_1_1491919462422_9686"><br clear="none"></div><div id="yui_3_16_0_ym19_1_1491919462422_9687">Alec</div><div class="yiv5018521785yqt1515883571" id="yiv5018521785yqt46952"><div id="yui_3_16_0_ym19_1_1491919462422_9688"><br clear="none"></div></div></div></div><br><br></div> </div> </div> </div></div></body></html>