Magnetostrictive displacement sensors deliver micron-level precision. Leveraging this strength, they play a vital role in monitoring applications such as industrial automation and precision manufacturing. Accurate displacement measurement of equipment in numerous scenarios including chemical workshops, port terminals and tunnel construction relies heavily on these sensors. Nevertheless, corrosive agents such as humidity, salt spray and chemical gases in such environments act as “invisible killers”, seriously impairing sensor performance and service life. How do magnetostrictive displacement sensors reinforce themselves to withstand harsh corrosive working conditions?

The First Line of Defense: Material Selection

Corrosion prevention starts with proper material selection at the source. Stainless steel is the preferred material for the housing and sensing rod of mainstream sensors. For extreme working conditions involving strong acids and alkalis, highly corrosion-resistant materials such as Hastelloy, PTFE and PFA serve as more suitable options.

• 304 Stainless Steel: Applicable to general humid workshop environments free of highly corrosive chemical media.
• 316L Stainless Steel: Compared with 304 stainless steel, 316L contains 2%~3% molybdenum (Mo) and reduced carbon content. It features outstanding resistance to chloride ion corrosion and pitting corrosion, and can withstand salt-laden port environments and chemical workshops splashed with acids and alkalis.
• Special Alloys & Engineering Plastics: For extreme environments with strong acids and alkalis, housings made of highly corrosion-resistant materials including Hastelloy, PTFE and PFA may be adopted. Do not underestimate engineering plastics; in certain chemical environments, these special materials outperform metals. For instance, PFA is nearly inert to all organic solvents, strong acids and strong alkalis. The ESC magnetostrictive displacement sensor developed by Zheda Jingyi adopts this material and is specially designed for environments with severe acid and alkali corrosion.

Figure 1: Zheda Jingyi Magnetostrictive Displacement Sensor with PFA Housing

The Second Line of Defense: Sealing & Protection

Gaps and connectors of sensors are the most vulnerable access points for corrosive media, and optimized sealing design is critical to blocking such ingress. Sealing rings are deployed for tight sealing at cable entries, adjusting screws and other positions. The housing is engineered to achieve high IP ingress protection ratings against dust and water. Typical ratings include IP67 (protected against temporary immersion), IP68 (protected against continuous immersion), and IP69K (protected against high-temperature high-pressure water jetting). These ratings directly reflect the sealing performance of the housing. In washing, dusty and humid environments, the IP rating serves as an essential technical benchmark.

Figure 2: Zheda Jingyi RS Waterproof Magnetostrictive Displacement Sensor with IP68 Ingress Protection Rating

The Third Line of Defense: Active Avoidance of Corrosive Sources

Even the most robust protection will fail due to improper operation and negligence. Actively mitigating risks is a controllable key measure for corrosion prevention, which can be implemented during installation.

• Installation location: Avoid areas with direct liquid splashing, condensed steam dripping, and positions directly above outlets of corrosive gas as much as possible.

• Protective accessories: For workstations with severe splashing, simple splash guards or protective sleeves can be installed on sensors, delivering favorable results at low cost.

• Standardized wiring: Ensure cable glands are fully tightened. Treat exposed wire ends with insulating sealant. Protect sealing surfaces and avoid scratching coatings and sealing rings with tools.

The Fourth Line of Defense: Periodic Maintenance

Regular maintenance constitutes the fourth line of defense against corrosion.

• Routine visual inspection: Check the sensor housing for abnormal dirt, crystal deposits and coating peeling during shift handover. Wipe surface contaminants with a clean soft cloth to prevent long-term adhesion-induced corrosion.

• Scheduled intensive inspection: Conduct monthly or quarterly inspections focusing on integrity of sealing areas and signs of leakage, aging and cracking of cable insulation, as well as loose or oxidized connectors. Replace damaged components promptly. The inspection interval shall be shortened for corrosive environments.

In summary, corrosion protection for high-precision magnetostrictive displacement sensors relies on a four-layer protection system: material selection + sealing design + hazard avoidance + routine maintenance. Comprehensive protection from inside out enables the sensors to withstand erosion under harsh working conditions while maintaining stable measurement accuracy. Proper maintenance throughout operation can extend service life and improve operational reliability.