Subsea conditions are considered some of the harshest working environments for sensors. The pressure exerted by water can cause the sensor to fail when subjected to these conditions for prolonged periods. In most similar applications, the cost of replacing a worn sensor can be more than the price of the device itself. As such, marine applications tend to look for sensors that have extended lifespans when operating in high pressure and submerged environments. Another concern with saltwater is its corrosive property which further contributes to the deterioration of the sensor.


Additional concerns with subsea working conditions


Apart from the corrosive property of seawater, pollutants in the water may also induce bacterial growth which may compromise the sensor’s performance. Microbial corrosion in metallic devices, especially those made with stainless steel is another severe problem faced by process control engineers when selecting a suitable sensor for subsea conditions. Because of the challenges posed by subsea working conditions, often the most feasible solution to apply is a linear variable differential transducer which many manufacturers like have in their inventory.





Advantages of using an LVDT for subsea applications


The design of a linear variable differential transducer includes a hermetically sealed housing which protects the components of the device from moisture and other external elements. Depending on the specifications of the manufacturer, LVDTs can come in various measurement range specifications as well as fabricated using alloys that can withstand the extreme pressure and corrosive properties of saltwater.


Features of an LVDT used in subsea applications


Hermetic sealing is a requirement when a position sensor will be subject to extreme pressure and corrosive compounds. This unique type of encapsulation ensures that no external element enters the internal coils and magnetic core making the sensor perform more reliably for a longer time. The hermetic sealing used in LVDT construction is typically made from nickel alloy and high-grade stainless steel which helps the ferromagnetic core to move freely while maintaining the integrity of the windings against external media.


Apart from hermetic sealing, LVDTs used in subsea applications also have a housing made using special materials. Ordinary stainless steel will not survive the conditions under seawater. Special alloys like nickel and 316 stainless steel are the only materials which can perform under the high-pressure working conditions underwater.


Specific examples of subsea applications of LVDT


Here are some of the particular applications of LVDTs in subsea conditions:


  • An LVDT is a vital part of safety and control functions used in offshore drilling rigs, desalination facilities, and oil and gas exploration sites.
  • Hydraulic and pneumatic cylinders found in many types of machinery used in subsea applications use linear variable differential transducers for position sensing.

There are several other possible applications of LVDTs in subsea environments. In each of these scenarios, some essential factors to consider include specific seawater conditions, and location. Apart from these factors, it is also crucial to determine the cost of acquisition as it impacts the overall feasibility of LVDTs as a long-term solution for similar applications under the same conditions.