Sensor de salinidade

When measuring a sample, the salinity sensor first obtains an accurate conductivity value, which is then converted into salinity through an internal algorithm.
Conductance or resistance is determined by measuring the current and voltage across the electrodes of the conductivity cell. Conductance (G) is defined as the reciprocal of resistance:

G = 1 / R = I / V

The conductance value depends on the geometry of the electrode plates and is represented by the constante celular (K), which is the ratio of the distance between the electrodes (L) to the electrode surface area (A):

K = L / A

Onde:

• K - Constante de célula do elétrodo de condutividade
• A - Área efectiva das placas de eléctrodos
• L - Distância entre as placas dos eléctrodos

This value is known as the constante da célula and can be calculated based on the electrode’s physical dimensions. For example, if two square electrode plates each have an area of 1 cm² and are spaced 1 cm apart, the cell constant is K = 1 cm⁻¹.
Se a condutância medida (G) utilizando este elétrodo for 1000 μS, então a condutividade da solução é:

κ = 1000 μS/cm

Conductance can be converted into standardized conductivity (κ), which is independent of the electrode configuration. This is done by multiplying the conductance by the cell constant:

κ = G × L / A = G × K

This conductivity value is then used to calculate salinity through predefined conversion formulas within the sensor.