Technical Solution for Conventional Five-Parameter Water Quality Sensor - AMT-SZ400

Introduction to Technical Requirements for Conventional Five-Parameter Water Quality Sensors

Conventional five parameters include water temperature,pH, dissolved oxygen (DO), conductivity, turbidity, widely used for online monitoring of surface water, reservoirs, water sources, sewage, and pipe networks, followingHJ/T96‑98、HJ915 series and other environmental protection industry standards, divided into six modules: general whole-unit requirements, special technical indicators for each parameter, mechanical structure, communication and electrical, calibration and maintenance, and environmental adaptability.

 

1. General overall technical requirements

Measurement principle

pH: composite glass electrode method;

Conductivity: four-electrode / Two-electrode electrode method;

Dissolved oxygen: fluorescence method preferred (membrane-free, low maintenance), also electrochemical polarographic method;

Turbidity:90° infrared scattered light method (ISO7027, resistant to water sample color interference);

Water temperature: thermistor, all parameters must have built-in automatic temperature compensation.

Output form: digital sensor,RS‑485 Modbus‑RTU, supportingHJ212 protocol, can be connected to automatic water quality stations; analog output is only an alternative.

Functional configuration: supports fault self-check, abnormal alarm; priority configuration of automatic cleaning (brush type / jet cleaning), reducing sediment and biofouling contamination; automatic recovery after power-off restart; local data caching, no data loss during network disconnection.

Monitoring mode: supports immersion installation, direct measurement of raw water, no filtration pretreatment (five parameters do not allow water sample filtration)

 

2. Core performance technical indicators for each parameter

Applicable to surface water online monitoring scenarios, typical indicators of industry standards, People's Republic of China...

Table

Parameter Measurement range Accuracy Repeatability Remarks

Water temperature 0～50℃ ±0.5℃ ≤0.2℃ as compensation source for other parameters

pH 0～14pH ±0.1pH ≤0.1pH Drift≤±0.1pH/24h

Conductivity 0‑200 mS/cm ±1%FS ≤0.5%FS Automatic temperature compensation to 25℃

Dissolved Oxygen 0‑20mg/L（0‑200% saturation) ±0.3mg/L ≤0.2mg/L Fluorescence method, air calibration

Turbidity 0‑1000NTU ±5% Reading or ±0.3NTU Take the larger ≤2% Reading High turbidity can expand range

Comparison acceptance allowable deviation (on-site comparison) water temperature:±0.5℃

‑ pH：±0.5pH

- Dissolved oxygen: ±0.8mg/L

- Conductivity: >100μS/cm ±10%；≤100μS/cm ±10μS/cm

- Low turbidity/ Use standard substance verification in extremely high range.

 

3. Mechanical and material requirements

Protection level: sensor probe IP68, can be immersed in water for a long time; cable waterproof connector, water pressure resistance ≥0.6MPa。

Housing material: main body 316L Stainless steel; for seawater conditions, use316L Titanium plated; sealing ring made of fluororubber, resistant to acid and alkali corrosion; cable resistant to hydrolysis and algae corrosion.

Installation method: supports immersion, buoy, and flow-through cell types; probe installation avoids bubbles blocking the sensing surface and avoids riverbed silt accumulation areas.

Flow rate: applicable water sample flow rate≤2.5m/s, if water flow is too high, a protective cover needs to be installed.

 

4. Electrical and environmental adaptability

Power supply:DC12‑24V DC power supply, low power consumption, suitable for field solar-powered stations.

Working environment temperature: sensor body‑10～60℃; measured water sample0‑45℃。

Storage temperature‑15～65℃; anti-condensation, anti-humidity, suitable for outdoor open-air and underwater humid environments.

 

5. Calibration, maintenance, and lifespan requirements

Calibration method

pH: two-point standard buffer solution calibration;

- Conductivity: calibrated with standard solution;

- Dissolved oxygen: air saturation calibration;

- Turbidity: calibrated with formazine standard turbidity solution.

Expected service life of sensor:

‑ pH Electrode:1‑2 years; dissolved oxygen fluorescent cap:1‑2 years; turbidity light source: ≥3 years; conductivity and temperature probes have longer lifespan.

Maintenance requirements: replaceable consumable parts (pH Membrane head,DO fluorescent membrane, sealing ring), easy to replace on site, no need to return the whole unit to the factory.

 

6. Software and data requirements

Output raw measurement values, temperature-compensated results, device status codes, and fault codes;

Supports remote reading of sensor parameters, remote triggering of calibration and cleaning;

Data storage: sensor can store historical records locally; supports connection to ecological environment monitoring platform HJ212‑2017 Transmission protocol.