Ameda Breastpump Diaphragms. Diaphragms are an important part of keeping milk safe in Ameda's closed system breast pumps. They act as a solid barrier to prevent air, moisture, and milk from entering into pump tubing. This keeps the “wet” side and the “dry” side of the breast pump separate. These silicone diaphragms are compatible with all Ameda® breast pumps and HygieniKit® Milk Collection Systems. Silicone; BPA free, DEHP free Package of 2 diaphragms.