<html><head></head><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px"><div id="yui_3_16_0_ym19_1_1470274650042_2592" dir="ltr"> Hi all,</div><div id="yui_3_16_0_ym19_1_1470274650042_2476" dir="ltr">need some group input here.</div><div id="yui_3_16_0_ym19_1_1470274650042_2475" dir="ltr">I was looking at a picture of Snoopy's dome that Doug posted on Facebook. (below)</div><div id="yui_3_16_0_ym19_1_1470274650042_2486" dir="ltr">The 6 dome retainers that are made of plastic were making me nervous.</div><div id="yui_3_16_0_ym19_1_1470274650042_2526" dir="ltr">There have been a couple of cases of domes blowing off. I think George Kitrige</div><div id="yui_3_16_0_ym19_1_1470274650042_2511" dir="ltr">was one of them. So I wanted a bit of analysis on this scenario in general.</div><div id="yui_3_16_0_ym19_1_1470274650042_2591" dir="ltr">What sort of overpressure can you expect at a maximum on a dive?</div><div id="yui_3_16_0_ym19_1_1470274650042_2571" dir="ltr">Doug's overpressure valve operates at .5psi but if you were 3psi overpressure</div><div id="yui_3_16_0_ym19_1_1470274650042_2717" dir="ltr">the valve wouldn't operate till you were 5ft from the surface & you would have a short</div><div id="yui_3_16_0_ym19_1_1470274650042_2702" dir="ltr">time to get the pressure down. Also wave movement would factor in & fluctuate the pressure quickly at that depth.</div><div id="yui_3_16_0_ym19_1_1470274650042_2701" dir="ltr">I think the K250 dome is 24" diameter. I calculated out that there would be 452lb </div><div id="yui_3_16_0_ym19_1_1470274650042_2790" dir="ltr">pressure on the dome retainers for every 1psi overpressure. I based this on the area </div><div id="yui_3_16_0_ym19_1_1470274650042_2791" dir="ltr">of a 24" disc, or should I be basing it on the area of the dome? (Sean)</div><div id="yui_3_16_0_ym19_1_1470274650042_2743" dir="ltr">At 3psi that would be 226lb lifting force on each of those 6 plastic retainers!</div><div id="yui_3_16_0_ym19_1_1470274650042_2854" dir="ltr">What is a good safety factor here? (Sorry for picking on Snoopy Alec)</div><div id="yui_3_16_0_ym19_1_1470274650042_2859" dir="ltr">Cheers Alan</div><div id="yui_3_16_0_ym19_1_1470274650042_2800" dir="ltr"><br></div><div id="yui_3_16_0_ym19_1_1470274650042_2769" dir="ltr"><br></div><div id="yui_3_16_0_ym19_1_1470274650042_2698" dir="ltr"><br></div></div></body></html>