A keel cooler having a standard header with an internal beveled bottom wall, with orifices on the inner wall of the exterior tubes extending into the header, the orifices being in the natural flow path of the coolant flow. The diaphragm valve portion regulates pressurized gas supplied from a pump to determine whether or not to open or close a needle valve. Therefore, the two opposite surfaces of the active layer can have different band gap values. The service provider uses a software package to accept data from the banking institution informing it of the client’s name, account number, deposit size, etc. The micro check valve is found to exhibit low cracking pressure, high reverse pressure, low reverse flow leakage, and negligible membrane-induced flow resistance when used as a valve over a micro orifice through which flow liquid and gas fluids.