Complete Causes of Signal Drift and Calibration Failure in High-Salt Environment Level Probes

I. Formation of a Dense, Insulating Salt Deposits Layer on the Probe Surface (The Primary Factor)

As high-salt liquids continuously evaporate, crystalline salts constantly precipitate on the probe’s sensing area and the outer walls of the electrodes, forming a non-conductive, hard salt crust.

Conductive Level Sensors: The electrodes are isolated by the salt scale, preventing normal detection of the medium’s conductivity signal, resulting in continuous level deviation;

Float / Capacitive Sensors: Scale buildup on the outer walls alters the medium’s dielectric constant and buoyancy reference, causing simultaneous shifts in both the zero point and measurement range;

Salt scale consists of dense inorganic crystals; simply wiping with clean water removes only the surface layer, while deep-seated crystals in crevices cannot be cleared.

In this scenario, on-site calibration merely forces a numerical correction; since the scale layer remains intact, the reading drifts again shortly after operation resumes, rendering the calibration completely ineffective.

II. High-salt media cause ionic polarization, generating polarization voltage at the electrodes

Over time, large amounts of cations and anions in saline wastewater adhere to the electrode surfaces. When energized, they form a stable polarization layer, generating an additional reverse potential that interferes with the measurement circuit.

The degree of polarization continuously changes with each operation, causing the measurement reference to fluctuate constantly; software calibration alone cannot eliminate physical polarization interference, resulting in persistent signal drift.

III. Chloride ions induce corrosion of the probe’s metal electrodes, damaging the sensing surface

In high-salt, chloride-ion environments, stainless steel electrodes and probe sensing surfaces experience pitting and crevice corrosion:

Pits and irregularities appear on the sensing surface, causing irregular changes in surface area and permanently altering the measurement reference;

Corrosion generates a metal oxide layer, further impeding signal conduction;

The hardware sensing elements have suffered physical damage; simple parameter calibration cannot repair hardware defects, and drift persists even after calibration.

IV. Alternating wet and dry conditions at the gas-liquid interface, with dynamic changes in scale layer thickness

Fluctuations in liquid level and evaporation cause the probe to be half-submerged and half-exposed; salt scale continuously precipitates and thickens at the liquid surface, with the scale layer thickness increasing continuously over time.

For the same probe, the scale layer thickness differs significantly after 1 hour versus 4 hours of operation, causing the measurement reference to continuously shift; calibration can only account for the current state of the scale layer, and subsequent thickening of the scale layer immediately causes the measurement to drift again.

V. Mixture of Trace Organics, Colloids, and Salt Crystals Forms Composite Adhesive Scale

Colloids and surfactants in wastewater combine with salt crystals to form viscous composite scale, which adheres far more strongly than ordinary scale and is difficult to flush away;

Composite scale exerts both insulating and dielectric interference effects, significantly distorting the liquid level signal; software calibration cannot compensate for this physical interference.

VI. Dynamic Fluctuations in Medium Concentration Cause Continuous Changes in Conductivity and Dielectric Properties

During intermittent concentration of the equipment, the salt content of the feed solution continuously increases, causing the medium’s conductivity and dielectric constant to fluctuate constantly.

Automatic calibration can only establish calibration values for a specific concentration; when the concentration changes, the measurement logic becomes distorted, resulting in erratic signal drift.