SensorsONE

Seawater Compatible Sensors

Sensors for use with seawater or protected from salt spray corrosion in marine environments. Select instruments with titanium, ceramic, plastic or marine bronze parts which have a high resilience to corrosion from salt water.

Sensors designed for reliable operation in seawater or marine environments subject to salt spray corrosion demand meticulous material selection to combat the aggressive, chloride-rich conditions. This category features instruments constructed with highly resilient materials such as specific titanium alloys, advanced ceramics like alumina and zirconia, engineered plastics including PEEK and PVDF, and specialized marine bronze alloys. These choices are critical for preventing electrochemical degradation, pitting, and crevice corrosion, ensuring long-term accuracy and durability for applications ranging from oceanographic research and desalination plants to aquaculture monitoring and equipment on marine vessels, where resistance to both direct immersion and atmospheric salinity is paramount.

Find out more about our Seawater Compatible Sensors to determine which product options and capabilities will best meet your application requirements.

The selection of appropriate materials is paramount when designing or specifying sensors intended for deployment in seawater or environments prone to salt spray corrosion. The highly conductive and chloride-rich nature of seawater presents a formidable challenge, accelerating various forms of corrosion that can compromise sensor integrity, accuracy, and operational lifespan. Instruments destined for such marine applications necessitate wetted parts and housings constructed from materials demonstrating exceptional resilience to these aggressive conditions.

Titanium alloys, particularly grades like Grade 2 (commercially pure) and Grade 5 (Ti-6Al-4V), are frequently specified due to their outstanding performance. Titanium forms a highly stable, tenacious, and self-healing passive oxide layer (TiO2) that provides excellent protection against general corrosion, pitting, and crevice corrosion, even in deaerated or high-velocity seawater. This inherent resistance makes titanium suitable for critical components such as pressure diaphragms, sensor bodies, and fasteners in long-term subsea deployments, including oceanographic moorings, remotely operated vehicles (ROVs), and autonomous underwater vehicles (AUVs).

Ceramic materials, such as alumina (Al2O3), zirconia (ZrO2), and silicon carbide (SiC), offer another tier of exceptional chemical inertness and corrosion immunity. These materials are not susceptible to electrochemical corrosion and can withstand a wide range of chemical attacks beyond just salinity. Their hardness and wear resistance are also beneficial. Ceramic elements are often employed in sensor faces, insulating components, or as robust transducer diaphragms in applications like conductivity cells, dissolved oxygen sensors used in aquaculture monitoring systems, or within instrumentation for desalination plants where both high salinity and varying chemical concentrations are encountered.

Engineered plastics play a crucial role in seawater compatible sensor design, offering a combination of chemical resistance, electrical insulation, and often a more cost-effective solution for complex geometries. Polymers like PEEK (Polyether Ether Ketone) exhibit remarkable mechanical strength at elevated temperatures alongside resistance to hydrolysis and a broad spectrum of chemicals. PVDF (Polyvinylidene Fluoride) is another excellent choice, known for its high purity, UV resistance, and robust defense against salts and acids, making it suitable for sensor housings or flow-through components in water quality monitoring systems. PTFE (Polytetrafluoroethylene) provides near-universal chemical resistance and low-friction surfaces, while more common plastics like Polypropylene (PP) or PVC (Polyvinyl Chloride) can be effective for less structurally demanding parts or in splash zone applications where constant immersion isn’t the primary concern.

Marine bronze alloys, specifically certain aluminum bronzes (e.g., C63200, C95500, C95800) and nickel-aluminum bronzes (NAB), are also utilized. These alloys form a protective, adherent surface film of aluminum oxide and cuprous oxide, which offers good resistance to seawater corrosion and, importantly, often exhibits a degree of biofouling resistance. This makes them suitable for components like valve bodies, sensor housings on ship hulls, or fittings in seawater cooling circuits. However, careful consideration of galvanic compatibility is essential when incorporating marine bronzes with other metallic materials in a sensor assembly to prevent accelerated corrosion of the less noble metal.

Beyond direct immersion, sensors operating in marine environments, such as those on coastal installations, offshore platforms, or onboard vessels, must also be protected from salt spray. Airborne saline particles can deposit on surfaces, and in the presence of moisture, create a highly corrosive electrolyte. Therefore, the external housing, connectors, and seals of such sensors must also be fabricated from, or adequately protected by, these corrosion-resistant materials to ensure long-term reliability and prevent premature failure in applications like meteorological buoys, structural health monitoring sensors on bridges, or equipment within engine rooms of marine craft. The meticulous choice of these specialized materials ensures that sensors maintain their performance specifications and operational integrity even when subjected to the relentless corrosive forces of saltwater and marine atmospheres.