Hypro 9910-KIT1725 Diaphragm Repair Kit for the D50 Diaphragm Pump. Repair Kit includes: 2 x Desmopan Diaphragms (# 9910-650085), 4 x Valve O-Rings (# 9910-320030), 1 x Accumulator Diaphragm (# 9910-650520). NOTE: Diaphragms will need to be replaced in most cases if you see the oil in the sight glass has a milky grey color or if oil comes out the discharge port. This most likely indicates one or more of the diaphragms have torn. Typically, diaphragms should be replaced every 3 months or 500 hours if your pump is used considerably.