A non-invasive blood pressure monitoring system, includes an air channel having one or more inlet and exhaust ports to ambient air. An electronically controlled pump inflates and deflates a cuff applied to a patient limb with air via the air channel. A water tight sealed housing containing electronic circuitry for processing signals used in deriving a measurement of patient blood pressure in conjunction with inflating and deflating the cuff. The water tight sealed housing also is sealed from the air channel.
