A new linear variable-differential transformer (LVDT), the submersible SSIR 937, from Macro Sensors, Pennsauken, N. J. can withstand deep-sea environments with external pressures up to 5,000 psi (7,500 psi of proof pressure). Like all LVDTs, the SSIR has excellent resolution and comes in 2, 3, and 4-in. measuring lengths. Other ranges can be custom ordered. A high-pressure Seacon-Branter subsea connector is standard. A welded connector is optional.
To get measurement signals to the surface, the output signal travels through a minimal number of pressure-sealed connections and I/Os, thanks to a 4 to 20-mA, two-wire, loop-powered I/O, which also limits noise on transmission lines. Users on the surface can also make offsets in the data-acquisition systems on the surface.