Precision Water Quality Sensors (pH/ORP/DO/EC)

// MODULE-02 / PROCUREMENT STRATEGY

Break the Brand Monopoly.

Traditional instrumentation giants force you to buy their proprietary displays. We provide open-architecture smart sensors that empower your own SCADA systems.

The Old Way

Proprietary Lock-in

You buy a $300 analog probe from a famous European brand. To read the data, you are forced to buy their $2,000 proprietary transmitter. When the probe inevitably fouls in wastewater, you are locked into buying their expensive replacements forever.

Analog Signal High CapEx Closed System

The WANDONG Way

Direct-to-PLC Architecture

Our sensors have the microprocessor built inside the probe. They output a standard RS485 Modbus-RTU digital signal. You wire the 4-core cable (VCC, GND, A, B) directly into your main PLC cabinet. No intermediate transmitters required. Save 80% on instrumentation CapEx.

Open Modbus-RTU Direct SCADA Integration

// MODULE-07 / LOCAL DISPLAY & CONTROL

Need Local Control?
We Have You Covered.

While our sensors can connect directly to your PLC, we understand that field operators often need local displays. Our universal controllers provide high-visibility LCD screens, 4-20mA outputs, and built-in relays for direct dosing pump control.

Dual SPST Relays (High/Low Alarms)

Isolated 4-20mA Current Loop Output

Automatic Temp Compensation (NTC10K)

Panel-Mount Universal Water Quality Controller

RS485 and 4-20mA Wiring Terminals for Water Quality Controller

Wall-Mounted IP65 Enclosure for Water Quality Transmitter

// MODULE-03 / SPECIFICATION MATRIX

The Sensor Arsenal.

From ultra-pure RO permeate to heavy MBR sludge. We have the exact electrode chemistry for your application.

WANDONG Smart Sensor Parameters

Model	Measurement Type	Range & Accuracy	Body Material	Output Signal
WD-PH-6001	Industrial pH (Wastewater)	0-14 pH (±0.02 pH)	PPS / PC	RS485 / 4-20mA
WD-PH-5013	Anti-Corrosion pH	0-14 pH (±0.02 pH)	Solid PTFE	RS485 / 4-20mA
WD-ORP-6001	Industrial ORP (Redox)	±2000 mV (±2 mV)	PPS / PC	RS485 / 4-20mA
WD-LDO-3002	Optical Dissolved Oxygen	0-20 mg/L (±3% FS)	SS316L / POM	RS485 Modbus-RTU
WD-EC-2000	Electrical Conductivity	0-20,000 µS/cm	SS316L	RS485 / 4-20mA

* Note: All smart sensors feature built-in NTC10K/PT1000 for automatic temperature compensation (ATC).
* Standard cable length is 5 meters. Custom lengths up to 50 meters available without signal degradation due to digital transmission.

Process Engineer's Note: RS485 Communication Limits

Unlike analog 4-20mA signals that degrade over distance, our RS485 digital signal can be transmitted up to 1,000 meters without a repeater. However, to ensure absolute signal integrity in noisy industrial environments, you must use twisted-pair shielded cables and install a 120-ohm terminating resistor at the far end of the Modbus network.

// MODULE-04 / ENGINEERING ANATOMY

Deconstructing Reliability.

Why do our sensors survive in harsh MBR sludge and corrosive chemicals? It's all about the reference junction and the optical physics.

3D Diagram of pH Double Junction and LDO Fluorescent Cap

Sensor Architecture

1. Annular PTFE Double-Junction (pH)

Standard pH sensors fail quickly in wastewater because sulfides and heavy metals poison the Ag/AgCl reference. Our industrial probes use a massive annular PTFE double salt bridge. This creates a long, tortuous diffusion path that physically blocks contaminants from reaching the reference electrode.

2. Luminescent Optical Technology (DO)

Traditional galvanic DO sensors require constant electrolyte refills and membrane replacements. Our LDO sensor measures the quenching of fluorescence by oxygen molecules. It consumes zero oxygen, requires no flow velocity, and the optical cap lasts over a year in thick MBR sludge.

3. Integrated Microprocessor

The analog-to-digital conversion happens inside the probe. This means the fragile millivolt signal is digitized immediately, making the cable completely immune to electromagnetic interference (EMI) from nearby VFDs and heavy pumps.

// MODULE-05 / MOUNTING CONFIGURATIONS

Universal 3/4" NPT.

Whether you are measuring RO permeate in a pressurized PVC pipe, or dropping a DO sensor 5 meters deep into an aeration basin, our dual-threaded design adapts instantly.

Inline Pipeline Mounting (Uses Bottom Thread)

Submerged Tank Mounting (Uses Top Thread)

Flow-Cell Bypass Mounting (For Clean Water)

NPT

WD-PH-6001 SENSOR

NPT

L: 160 mm

Top 3/4" NPT (For Extension Pole) Bottom 3/4" NPT (For Pipe Tee)

// MODULE-06 / INDUSTRIAL RELIABILITY

Zero Downtime.

Water treatment plants are electrically noisy environments. Our sensors and controllers are engineered to survive severe electromagnetic interference without freezing or crashing.

Hardware Watchdog (WDT)

Cheap controllers freeze and crash. Our systems feature a dedicated Hardware Watchdog Timer. If a severe power surge interrupts the CPU, the Watchdog instantly reboots the system in milliseconds, ensuring your dosing pumps never run out of control.

Tier-1 Microprocessors

We don't compromise on the brain. Our sensors utilize imported microprocessors from Texas Instruments (TI) and Microchip, delivering 10MBit/s high-speed conversion and absolute signal stability.

EMC Shielding & Chokes

Industrial sites have massive VFDs (Variable Frequency Drives) that destroy weak signals. Our circuits feature heavy-duty choke inductors and full PCB conformal coating to block EMI and prevent moisture tracking.

// MODULE-08 / AUTOMATED DOSING

Closed-Loop Control.

Don't just measure the water; control it. Our pH/ORP controllers feature built-in High/Low relays to directly drive your acid and alkali dosing pumps.

P&ID Diagram of Automated pH Neutralization Dosing Control Loop

pH Dosing Control Loop Showcasing the sensor -> controller -> dosing pump feedback loop.

1

Real-Time Measurement

The WD-PH-6001 sensor continuously monitors the neutralization tank, sending instant pH values to the local controller.

2

High/Low Relay Activation

If the pH drops below the setpoint (e.g., pH 6.0), the controller's "Low Alarm" relay closes, instantly sending power to the Alkali dosing pump.

3

Automated Neutralization

The pump injects NaOH until the pH reaches the safe zone (e.g., pH 7.0). The relay opens, stopping the pump. Zero human intervention required.

// MODULE-09 / WIRING & INTEGRATION

Plug, Play, and Control.

From simple RO monitoring to complex SCADA networks. Our sensors integrate seamlessly into your existing architecture.

Standard 4-Wire RS485 Connection

Red Wire VCC (10~30V DC)

Black Wire GND (Ground)

Yellow Wire RS485 - A

Blue Wire RS485 - B

* Note: Up to 254 sensors can be daisy-chained on a single RS485 bus, drastically reducing cabling costs across large plants.

Electroplating & Desulfurization

Use our PTFE anti-corrosion pH probes to monitor highly acidic electroplating wastewater and control scrubber desulfurization processes.

MBR Aeration Control (LDO)

Drop our Optical DO sensor into the bioreactor. Wire it to the PLC to control the aeration blowers via VFD. Maintain exact DO levels (e.g., 2.0 mg/L) and save massive electricity.

RO Permeate Monitoring (EC)

Install inline Conductivity sensors on the RO product water line to continuously monitor membrane salt rejection performance and trigger alarms if quality drops.

// MODULE-10 / PROVEN IN THE FIELD

Powered by WANDONG.

We don't just sell components; we build the heavy-duty systems that rely on them. Our smart sensors and controllers are the nervous system of our own containerized RO and MBR plants deployed globally.

The Integrator's Advantage

Because we use these exact instruments in our own $500,000+ EPC projects, they undergo rigorous internal quality control that pure trading companies simply cannot match. We stake our entire plant's automation on these sensors.

WANDONG PLC Control Panel Integrating Smart Water Quality Sensors

FIELD DEPLOYMENT

WANDONG Main PLC Cabinet

Showcasing our sensors wired directly into the Siemens S7-1200 PLC via RS485.

// MODULE-11 / DIGITAL CALIBRATION

Software Configuration.

Every WANDONG smart sensor comes with our free PC configuration software. Connect the sensor to your laptop via a USB-to-RS485 adapter to easily set baud rates, change slave addresses, and perform precise calibrations.

1-Point & 2-Point Digital Calibration

Full Modbus Register Mapping Provided

Adjustable Baud Rate (1200 to 115200)

PC Configuration Software and Modbus Register Mapping for Smart Sensors

WANDONG Sensor Configurator Showcasing the digital calibration tool and register addresses.

// MODULE-12 / THE ENGINEER'S UNBOXING

Ready to Wire.
Out of the Box.

We deliver a risk-free deployment experience engineered for remote sites and harsh environments.

Industrial-Grade Traceability

Every sensor cable features a laser-printed tag with exact wiring pinouts (VCC/GND/A/B) and a unique serial number. No guessing for your electrical team.

Factory Calibration Cert

Open the box and find the hardcopy Factory Calibration Certificate right on top. Every sensor is 2-point calibrated in standard buffer solutions before shipping.

KCL Preservation Cap

pH and ORP glass bulbs are extremely fragile and must remain wet. Our sensors are shipped with a sealed hydration cap filled with 3M KCL solution to ensure a 12-month shelf life.

// MODULE-13 / LOGISTICS MATRIX

Optimized for Global Transit.

We speak the language of freight forwarders. Packaging optimized for rapid DHL/FedEx air-freight.

Single Sensor Carton

Dimensions (L×W×H)

~250 × 100 × 50 mm

Gross Weight

~0.5 kg (1.1 lbs)

Cable Included

5 Meters Standard

Packaging

Shock-proof foam

Master Carton

50 pcs

Ideal for EPC project bulk air-freight.

Standard Pallet

~500 pcs

For wholesale distributors.

// MODULE-15 / TECHNICAL FAQ

Hardcore FAQ.
Engineering-Grade Answers.

Do I absolutely need to buy a controller/transmitter?

No! That is the beauty of our Direct-to-PLC architecture.

If you have a central PLC (like Siemens S7 or Allen-Bradley) with an RS485 module, you can wire our smart sensors directly to it. You only need to buy our Controller if you want a local LCD display in the field, or if you need the Controller's built-in Relays to directly switch dosing pumps on and off.

Why is Optical DO (LDO) better than traditional Galvanic DO sensors?

Traditional Galvanic/Polarographic sensors consume oxygen to measure it, meaning they require constant water flow past the tip. They also require frequent electrolyte refills and fragile membrane replacements.

Our Optical LDO sensor uses fluorescence quenching. It consumes zero oxygen, requires no flow, has no electrolyte to leak, and the robust optical cap lasts for over a year even in thick, abrasive MBR sludge.

How do I calibrate the Optical DO sensor?

Calibration is incredibly simple using our PC software. For a 100% saturation calibration: place the sensor in air-saturated water (or moist air) for 30 minutes until the reading stabilizes, then click the "100% Calibration" button. For zero-point calibration, immerse the sensor in a 5% Sodium Sulfite (Na2SO3) solution for 1 hour, then click "Zero Calibration".

What is your warranty policy?

We provide a 12-Month Warranty on the sensor electronics and controllers. Please note that the pH glass bulb and the LDO fluorescent cap are considered consumable items. The warranty is voided if the sensor is dropped, if the cable is cut/spliced without proper waterproofing, or if the sensor is exposed to temperatures/pressures beyond its rated limits.

Can the sensors be fully submerged underwater?

Yes. The sensor body itself is IP68 rated and designed for continuous submersion in aeration tanks or open channels. However, you must ensure that the top cable junction is either kept above the water line using an extension pole, or properly sealed with a waterproof junction box to prevent capillary water ingress into the cable.

What is the maximum cable length for the RS485 signal?

Unlike fragile analog signals (mV or 4-20mA) that degrade quickly over distance, our digital RS485 Modbus signal can be transmitted up to 1,000 meters (3,280 feet) without a repeater. Just ensure you use a high-quality twisted-pair shielded cable (e.g., RVVP) and install a 120-ohm terminating resistor at the PLC end.

// MODULE-16 / INITIATE PROTOCOL

YOUR 50,000m²
OEM SUPPLY BACKEND.

Stop being held hostage by proprietary instrumentation brands. Whether you need a single LDO sensor for an MBR tank, or 50 pH sensors for a chemical plant, our engineers will provide a precise Modbus-ready proposal within 1 hour.

1h

INITIAL RESPONSE

1-ON-1

CUSTOM PROPOSAL

$0

CONSULTATION FEE

// SECURE YOUR SUPPLY CHAIN

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Notes & Application Details

If you require Modbus register addresses for PLC programming, please request our digital integration manual in the notes.

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Direct-to-PLC. Zero Lock-in.