A process fluid level measurement system is configured to measure a level of at least one process fluid in a vessel. The vessel has a cage with at least one annular isolator located inside the cage. The at least one annular isolator has a band-shaped isolator diaphragm. A differential pressure transmitter is operably coupled to the annular isolators) and is configured to generate a level output based, at least in part, upon pressure measured relative to the annular isolator(s).