A pump 1, wherein the sheet is in the shape of a substantially spherical or conical cap complementary to the inside surface of {TAIL ~ the side plate} so as to fit against it as closely as possible, with the convex side of this shape facing towards {HEAD ~ the inside} of the chamber 
A pump 1 , wherein the sheet is in the shape of a substantially spherical or conical cap complementary to the inside surface of { TAIL ~ the side plate } so as to fit against it as closely as possible , with the convex side of this shape facing towards { HEAD ~ the inside } of the chamber
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH