<div dir="ltr"><div class="gmail_default" style=""><font color="#000000"><span style="font-size:12.8px">Thanks to all that responded. Apparently, there's no "O" ring in the Jac-Pac itself.</span></font></div><div class="gmail_default" style=""><br></div><div class="gmail_default" style=""><span style="font-family:arial,sans-serif;font-size:12.8px;color:rgb(0,0,0);font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline"><<O rings only come in standard sizes. Except for nasa rocket booster orings.? ?</span><br style="color:rgb(0,0,0);font-family:arial,sans-serif;font-size:12.8px;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial"><span style="font-family:arial,sans-serif;font-size:12.8px;color:rgb(0,0,0);font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">I go to grainger or whomever and order one of those assortment kits if I'm not sure what size I need.? Which for me is everytime, I have no idea how you would even measure one.??>></span></div><div class="gmail_default" style=""><br></div><div class="gmail_default" style="">I have an assortment/kit of about 30 various sizes although usually not the one I need (of course). I believe one measures an "O" ring by the diameter of a cross-section and the diameter of the ring itself.</div><div class="gmail_default" style=""><br style="font-family:arial,sans-serif;font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial"><span style="font-family:arial,sans-serif;font-size:12.8px;color:rgb(0,0,0);font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline"><The o ring sealing surfaces need to be completely clean and smooth.? Something as small as a human hair across the surface provides a leakage path.? ?If you have shreds of rubber in there,? then time to clean and inspect.? Lubricate if indicated.? If the metal is gouged, then repair or replacement of the fitting is indicated.?></span><br></div><div class="gmail_default" style=""><span style="font-family:arial,sans-serif;font-size:12.8px;color:rgb(0,0,0);font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline"><br></span></div><div class="gmail_default" style=""><span style="font-family:arial,sans-serif;font-size:12.8px;color:rgb(0,0,0);font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">I have dealt with quite a few pneumatic devices in my time so I'm pretty aware of what can cause leaks. It appeared to me that there could have been an "O" ring in the Jac-Pac as that's where I found the shreds of one but apparently it came from a CO2 cylinder of which I have several. What is curious is that the "O" rings on the cylinders are clear while the shreds were black. I did notice that one cylinder is missing its ring though, however that was not the cylinder that was leaking. The whole thing is a mystery. I did try another cylinder and there was no leak.</span></div><div class="gmail_default" style=""><span style="font-family:arial,sans-serif;font-size:12.8px;color:rgb(0,0,0);font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline"><br></span></div><div class="gmail_default" style=""><span style="font-family:arial,sans-serif;font-size:12.8px;color:rgb(0,0,0);font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">Laters,</span></div><div class="gmail_default" style=""><span style="font-family:arial,sans-serif;font-size:12.8px;color:rgb(0,0,0);font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline"><br></span></div><div class="gmail_default" style=""><span style="font-family:arial,sans-serif;font-size:12.8px;color:rgb(0,0,0);font-style:normal;font-variant-ligatures:normal;font-variant-caps:normal;font-weight:400;letter-spacing:normal;text-align:start;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px;background-color:rgb(255,255,255);text-decoration-style:initial;text-decoration-color:initial;float:none;display:inline">Paul 1</span></div></div>