<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_1487282654008_2433"> Wonder if something like the attached image of a spray paint pot would work, </div><div id="yui_3_16_0_ym19_1_1487282654008_2498">with modifications, as a pressure compensator.</div><div id="yui_3_16_0_ym19_1_1487282654008_2465" dir="ltr">Machine a plastic piston to fit inside with o-ring grooves & a recess to encapsulate a </div><div id="yui_3_16_0_ym19_1_1487282654008_2487" dir="ltr">spring. Drill holes in the cap to let water in.</div><div id="yui_3_16_0_ym19_1_1487282654008_2486" dir="ltr">Alan</div><div id="yui_3_16_0_ym19_1_1487282654008_2432" dir="ltr"><img id="yui_3_16_0_ym19_1_1487282654008_2479" alt="Related image" src="http://p.luckyretail.com/Uploadfile/20160919/080096/080096.jpg" data-id="771204b4-2a80-8eaf-372d-c69942890c96"></div></div></body></html>