Hypro 9910-KIT1725 Diaphragm Repair KitHypro D503 Diaphragm Repair Kit (9910 KIT1881) will provide repairs for the diaphragms on your Hypro D813 pump. If the oil in your diaphragm pump has a milky gray color, you most likely will need to replace the diaphragms. Running a diaphragm pump with oil that is mixed with chemical can cause extensive damage to your pump. Keep this kit handy if your D503 is in constant use. We recommend changing the diaphragms every 3 months or 500 hours of use.