Page 55: of Marine Technology Magazine (November 2010)

Pressure and Seawater Resistant LVDT Position Sensors for incorporation into sub-sea measurement systems used to monitor structural movement for long-term Finite

Element Analysis of offshore platforms, pipelines, der- ricks, moorings and other critical high-stress members on offshore oil platforms. The High-Pressure and Seawater

Resistant LVDT Position Sensors can also be used to measure the position of the valves, called chokes, on sub- sea oil well control towers (called Christmas trees), locat- ed at the wellhead, as well as controlling or measuring position of robotic arms and actuators.

As seawater applications often require a design service life of as much as 20 years while being exposed to seawa- ter pressures up to 7500 psi, Macro Sensors High-Pressure and Seawater Resistant LVDT Position Sensors are designed from 316SS and Inconel 625 for pressure and corrosion resistance. Macro Sensors High-Pressure and

Seawater Resistant LVDT Position Sensors also resolve the problem of getting a signal back to the surface for monitoring, recording and/or controlling some physical action taking place on the surface or sea water, even in great water depths.

To minimize the number of pressure-sealed connections and I/Os, a 4-20mA two-wire, loop-powered I/O can be utilized, which is then, converted to a RS485 signal for transmission to the surface. Typically, a digital converter is contained in a high-pressure sealed bottle located near- by. A 4-20mA I/O also minimizes any noise over long transmission lines. Offsets can be easily made in the data acquisition system on the platform above. www.astsensors.com

DT-X SUB: New Autonomous

Submersible Echosounders

Seattle-based BioSonics debuted its DT-X SUB, a self-contained, programmable echosounder for scientific data collection. The system consists of a scientific echosounder with data storage and power sys- tems integrated and packaged in a compact, waterproof housing. It is designed to be lightweight, and has no external cabling. It is intend- ed for monitoring and assessing all types of aquatic organisms, from zooplankton to marine mammels. According to the company, increas- ing demand for information on aquatic animal’s temporal behavior and distribution over time drove development of the DT-X SUB. The unit offers solid state RAID storage and fully programmable duty cycle and echosounder configuration.

Email: emunday@ biosonicsinc.com

Concept drawing of

DT-X SUB shown deployed from a seafloor tripod mount to collect data on all targets in water column. www.seadiscovery.com Marine Technology Reporter 55