Corrosion rate senors of Standard Conformity

Zero resistance ammeter (ZRA) sensors

Galvanic Corrosion Monitoring: When two dissimilar metals are physically connected, the ZRA tracks how much current passes between them to determine which metal is corroding (the anode) and how fast ISO 9223 

ER corrosion rate sensors :

Sensors can be made of various pure metals and alloys, including bare steel and stainless steel, zinc, aluminum, copper, silver, and lead. The sensitivity of sensors increases with decreasing thickness(0.03mm to 0.5mm), and the longer the thickness, the longer their service life. Currently, resistive sensors are mainly used to monitor bare metal surfaces

EIS corrosion monitoring(Wet corrosion):

The protective nature of surface films and coatings can be characterized in terms of impedance

Principle: The corrosion reaction can be represented by the equivalent circuit shown in the figure above. Here, Z represents impedance, Rp represents polarization resistance
(proportional to corrosion resistance), Cdl represents double-layer capacitance, and Rs represents solution resistance. When ω → ∞, Z ≈ Rs; when ω → 0, Z ≈ Rs + Rp.
In this scenario, since the relationship Z ≈ Rs + Rp holds, the solution resistance (Rs) can be determined from the high-frequency range, and the polarization resistance (Rp) can be
calculated by subtracting the Rs value. The reciprocal of the polarization resistance corresponds to the corrosion rate.

Sensor according to ANSI/ISA-71.04-2013,ISO 12944 and ISO 22858,ANSI/NACE TM0416‑2023,AMPP TM21449‑2021