Solving the problems of data drift and frequent maintenance in turbidity measurement

The YEX-S2-ZS-8S Online Turbidity Sensor adopts the 90° scattered light principle, combined with pure quartz optical path and infrared LED light source, suppressing zero drift caused by external stray light interference and light source attenuation from the source. It features a built-in self-cleaning brush and Pt1000 automatic temperature compensation, significantly extending the manual maintenance cycle.

• Stable Measurement: Pure quartz optical path + infrared LED, strong resistance to external stray light interference, minimal long-term drift

• Easy Integration: RS-485 Modbus RTU + optional 4-20mA dual output, compatible with PLC, RTU, and touch screens

• Harsh Environment Adaptation: IP68 (20m water depth), 316L housing, -5～65℃ storage, 0～60℃ operating

YEX-S2-ZS-8S Online Turbidity Sensor Product Overview

Yexsensor YEX-S2-ZS-8S is an integrated online turbidity sensor specially designed for applications requiring long-term continuous monitoring with sensitive maintenance costs. The product integrates the optical measurement unit, temperature sensor, signal processing circuit, and mechanical cleaning device into a 316L stainless steel housing, and can directly output standard signals without an external controller.

Compared with traditional scattered light turbidity meters, this product focuses on solving three major engineering pain points: high noise in low turbidity range, nonlinearity in high turbidity range, and data drift caused by window contamination. The cleaning brush can be triggered by the user as needed (via Modbus command), effectively suppressing biofilm and particle attachment. It has undergone 72-hour aging and stability testing before shipment, ensuring immediate use upon power-on.

YEX-S2-ZS-8S Online Turbidity Sensor Core Advantages and Technical Features

1. 90° Scattered Light + Pure Quartz Optical Path, Strong Anti-Interference

Adopts the 90° scattered light measurement principle in accordance with ISO 7027 standard, combined with pure quartz glass optical window for stable transmittance, corrosion resistance, and scratch resistance. The sensor incorporates a light trap structure internally to effectively absorb reflected stray light. It maintains stable readings even under strong ambient light (such as outdoor pools or direct sunlight) or when installed near transparent pipelines.

2. Dual Output Interfaces, Easy Integration

• RS-485 (Modbus RTU) is standard configuration, can be directly connected to configuration screens, distributed IO, and wireless data transmission stations.

• 4-20mA analog output is optional, convenient for connecting to legacy PLCs or systems requiring only single-variable control.

• Modbus registers allow reading of turbidity value, temperature value, and cleaning brush status, and support writing calibration coefficients and cleaning trigger commands.

3. Self-Cleaning Brush + Pt1000 Temperature Compensation

• Built-in Self-Cleaning Brush: Motor-driven scraping of the optical window, can be triggered regularly or manually via Modbus commands. Significantly reduces biofilm and sediment accumulation, lowering manual wiping frequency by 50%~70% throughout the product lifecycle.

• Pt1000 Temperature Compensation: Operating range 0～60℃, accuracy ±0.3℃, automatically corrects the effect of temperature on scattered light intensity, improving measurement consistency across a wide temperature range.

4. Wide Range and Reasonable Accuracy Grading

Three range options are available (specify when ordering):

• 0~20.00 NTU (resolution 0.01) — suitable for high-purity water, tap water, ultrapure water

• 0~1000.0 NTU (resolution 0.1) — suitable for surface water, plant effluent

• 0~4000.0 NTU (resolution 0.1) — suitable for wastewater, industrial circulating water

YEX-S2-ZS-8S Online Turbidity Sensor Technical Specifications

YEX-S2-ZS-8S Online Turbidity Sensor Typical Application Scenarios

• Drinking Water and Water Treatment Plants: Online turbidity monitoring before filtration, after filtration, and at plant outlet, combined with PLC for closed-loop chemical dosing control.

• Surface Water and River Sections: Small water quality monitoring stations and buoy systems; low power consumption is suitable for solar power supply.

• Wastewater Treatment Plants: Turbidity monitoring at biochemical tank effluent, secondary sedimentation tank, and final outlet; self-cleaning brush reduces biofilm interference.

• Industrial Circulating Cooling Water: Continuous monitoring in bypass or tank to warn of heat exchanger scaling or leakage.

• Aquaculture and Hatcheries: Early warning of feed residue and excessive suspended solids to avoid stress on fish and shrimp.

• Rainwater and River Outlets: Turbidity surge alarms during dry or rainy seasons to assist pipeline network management.

FAQ

Q1: Does the sensor require frequent calibration?

In stable water quality (such as tap water) with the self-cleaning brush, it is recommended to perform two-point calibration every 3~6 months. In sewage or high biological attachment environments, the cycle can be shortened to 1~3 months according to regulatory requirements.

Q2: How does the cleaning brush work? Does it run automatically?

The cleaning brush is triggered by Modbus commands. Users can set timed tasks (e.g., scraping once every 24 hours) or trigger manually. It does not run continuously by default to avoid premature wear.

Q3: Can it be directly connected to my existing PLC?

Yes. The standard RS-485 interface supports Modbus RTU protocol. Most PLCs (Siemens, Mitsubishi, Rockwell, Delta, Huichuan, etc.) can read it directly. If the PLC only has 4-20mA input, please select the version with current output.

Q4: Does the cable need waterproof treatment?

Yes. Although the cable itself is waterproof, all wiring points (between sensor and extension cable, entering control cabinet) must be sealed. It is recommended to use gel-filled junction boxes or dedicated waterproof connectors.

Q5: What is the accuracy at high turbidity (>1000 NTU)?

±5% relative error in the 200~4000 NTU range. For example, at 1500 NTU, error ≤75 NTU. It is recommended to select the 0~4000 range model for high turbidity applications.

Q6: Is the minimum detection limit of 0.01 NTU realistically achievable?

In zero turbidity solution, static noise ≤0.01 NTU. In actual field applications, affected by microbubbles and particle distribution, 0.05 NTU and below is considered the reliable resolution range.

Q7: Can the sensor be installed horizontally?

Vertical submersible installation (measuring face downward) is recommended. Horizontal installation may cause bubbles to remain on the optical window, affecting readings. If horizontal installation is necessary, sufficient flow velocity must be ensured to expel bubbles.

Q8: What is the maximum temperature and pressure the probe can withstand?

Operating temperature 0～60℃, maximum pressure 0.2MPa (approx. 20 meters water head). Not suitable for steam or high-temperature sterilization environments.

Summary

The Yexsensor YEX-S2-ZS-8S Online Turbidity Sensor provides a reliable low-maintenance measurement solution for water treatment, environmental monitoring, and industrial process control. The combination of its optical design (pure quartz optical path + infrared LED) and mechanical structure (self-cleaning brush + 316L housing) significantly reduces on-site data drift and manual wiping frequency. The dual output interfaces (Modbus RTU + optional 4-20mA) allow it to quickly integrate into modern digital systems while remaining compatible with traditional analog acquisition.