Zming Environmental HQ-10-pH Digital Online pH Sensor
| Brand | Zming Environmental Technology Co., Ltd. |
|---|---|
| Origin | Shanghai, China |
| Manufacturer Type | Authorized Distributor |
| Country of Origin | China |
| Model | HQ-10-pH |
| Instrument Type | Pen-style |
| Parameter Type | Single-parameter (pH) |
| Measurement Range | 0–14 pH |
| Resolution | 0.01 pH |
| Accuracy | ±0.07 pH |
| Repeatability | ±0.08 pH |
| Temperature Compensation Accuracy | ±0.04 pH |
| Response Time | 15 s |
| Offset at pH 4.00 | −0.02 pH |
| Offset at pH 6.86 | +0.03 pH |
| Offset at pH 9.18 | −0.05 pH |
| Output Interface | RS485 with Modbus RTU protocol |
| Enclosure Rating | IP68 |
| Housing Material | Stainless Steel (316L) |
Overview
The Zming Environmental HQ-10-pH Digital Online pH Sensor is a compact, industrial-grade electrochemical transducer engineered for continuous, real-time monitoring of hydrogen ion activity in aqueous environments. It operates on the potentiometric principle: a glass pH sensing electrode and integrated reference electrode generate a millivolt-level potential difference proportional to the logarithm of H⁺ concentration, per the Nernst equation. This analog signal is digitized internally using a high-stability 24-bit ADC, eliminating external signal degradation and enabling direct digital transmission. Designed specifically for unattended deployment in surface water, wastewater effluent, municipal intake channels, and industrial process streams, the HQ-10-pH integrates temperature compensation via a co-located Pt1000 thermistor—ensuring measurement integrity across dynamic thermal conditions without manual recalibration.
Key Features
- Monolithic digital architecture: All signal conditioning, temperature compensation, and A/D conversion occur within the sensor housing—no external transmitter required.
- Industrial composite pH electrode: Dual-junction Ag/AgCl reference system with gel-filled electrolyte and low-resistance pH glass membrane, optimized for long-term drift stability (<0.01 pH/day) and resistance to sulfide poisoning or protein fouling.
- Auto-compensating temperature measurement: Integrated Pt1000 sensor provides ±0.1 °C accuracy; compensation algorithm conforms to DIN 19265 and ISO 10523 standards.
- Ruggedized mechanical design: 316L stainless steel body with IP68-rated sealing ensures operational reliability in submerged, high-vibration, or chemically aggressive environments—including chlorinated water, brackish influent, and mildly acidic/alkaline process streams.
- Standardized digital communication: RS485 interface compliant with Modbus RTU protocol (addressable from 1–247), supporting multi-drop network configuration up to 1,200 m total bus length with termination resistors.
Sample Compatibility & Compliance
The HQ-10-pH is validated for use in natural waters (rivers, lakes, reservoirs), secondary-treated wastewater, cooling tower make-up, and potable water distribution networks. It is not intended for non-aqueous solvents, high-viscosity slurries (>100 cP), or strongly oxidizing media (e.g., >5 ppm free chlorine without periodic cleaning). The sensor meets CE marking requirements under the Electromagnetic Compatibility Directive 2014/30/EU and Low Voltage Directive 2014/35/EU. Its measurement methodology aligns with ASTM D1293 (Standard Test Methods for pH of Water) and ISO 10523 (Water quality — Determination of pH). While not FDA 21 CFR Part 11–certified out-of-the-box, audit trails and data integrity can be maintained when integrated into SCADA or LIMS platforms with appropriate validation protocols.
Software & Data Management
The HQ-10-pH outputs calibrated pH values as 16-bit signed integers (scaled 0–1400 = 0.00–14.00 pH) and temperature as 16-bit integer (°C × 10). No proprietary software is required—Modbus registers are fully documented in the device’s technical specification sheet. Integration with third-party SCADA systems (e.g., Ignition, Siemens Desigo, Schneider EcoStruxure) is achieved via standard Modbus TCP-to-RTU gateways. For laboratory traceability, raw sensor output can be logged with timestamping and checksum verification; optional firmware updates support enhanced diagnostics (electrode impedance monitoring, calibration history retention) via UART bootloading.
Applications
- Real-time compliance monitoring at EPA-regulated NPDES discharge points.
- Automated feedback control in lime softening or acid dosing loops within water treatment plants.
- Long-term ecological assessment of acid mine drainage (AMD) remediation sites.
- Performance verification of reverse osmosis membranes in desalination pre-treatment stages.
- QA/QC screening in food & beverage production lines where rinse water pH must remain within 5.5–8.5 per USP environmental monitoring guidelines.
FAQ
What calibration protocols are supported?
The HQ-10-pH supports two-point calibration using standard buffer solutions (e.g., pH 4.01 and 7.00, or 7.00 and 10.01) via Modbus register write commands. Calibration coefficients are stored non-volatilely and persist through power cycles.
Is field recalibration possible without removing the sensor?
Yes—calibration may be performed in-situ using portable buffer kits and a handheld Modbus master device or compatible HMI terminal.
How often should the electrode be cleaned or replaced?
Under typical municipal water conditions, cleaning every 2–4 weeks with mild detergent or 0.1 M HCl is sufficient. Electrode service life averages 12–18 months; replacement is recommended when response time exceeds 30 s or offset exceeds ±0.2 pH across all three calibration points.
Does the sensor require a separate power supply?
It operates on 12–24 VDC, consuming ≤150 mW; power and data share the same RS485 twisted-pair cable (with proper isolation and surge protection per IEC 61000-4-5).
