Abstract: Pressure sensors or pressure gauges are protected from water and other foreign materials by a pressure sensitive contamination trap comprising a sealed vessel containing a first fluid, said vessel having an intake conduit to the vessel interior above the level of the first fluid and buffer tube filled with a second fluid, said buffer tube projecting below the level of the first fluid, said second fluid being in contact with said first fluid at one end of the buffer tube and with a pressure sensor at the other end of the buffer tube. The second fluid is of a lower specific gravity and immiscible with the first fluid. The two fluids are preferably chemically inert with respect to each other.