MDX500 Multi-Parameter Analyzer

1. Integrated Sensor Array: The device is a “host” unit that contains multiple ports and interfaces for various sensor cartridges or modules. Each parameter is measured by a dedicated, specialized sensor using its own distinct physical or electrochemical principle.

2. Simultaneous Data Acquisition: A central microprocessor controls all the sensors, powering them and collecting their individual analog signals at the same time.

3. Signal Processing & Compensation: The onboard computer converts these raw analog signals into digital values. A critical function is applying compensation algorithms to correct for cross-interferences between parameters. For example:

   • pH readings are automatically temperature-compensated.

   • Dissolved Oxygen (DO) saturation calculation is compensated for both temperature and salinity.

   • Conductivity is compensated for temperature to report values at a standard 25°C.

4. Data Output: The processed data for all parameters is then output as a comprehensive dataset, typically shown on the instrument’s display, logged to internal memory, or transmitted in real-time via cable, Bluetooth, or satellite.

Key Sensors & Their Individual Principles:

• pH: Measures the voltage potential difference between a glass pH electrode and a reference electrode.

• Dissolved Oxygen (DO): Uses a Clark-cell type membrane electrode where oxygen diffuses through a membrane and is reduced at a cathode, producing a current proportional to DO concentration.

• Conductivity: Applies an AC voltage between two or four electrodes to measure the electrical current carried by ions in the water.

• Turbidity: Emits a light beam (usually near-IR) into the water and measures the amount of light scattered at a 90-degree angle by suspended particles.

• ORP (Oxidation-Reduction Potential): Measures the voltage potential of a platinum electrode relative to a reference electrode, indicating the oxidizing or reducing capacity of the water.

• Temperature: Measured by a thermistor (a resistor whose resistance changes predictably with temperature), which is essential for compensating all other sensor readings.