The ERUN-SZ4-K6 online residual chlorine analyzer delivers laboratory-grade accuracy (0.001 mg/L resolution, ±3% accuracy) with zero reagent consumption—backed by CE, ISO 9001, RoHS, and SIL4 certifications.
The global residual chlorine monitor market is projected to grow from US$415 million in 2025 to US$650 million by 2031, at a CAGR of 7.8%. Water treatment facilities worldwide are shifting from traditional DPD reagent-based methods to electrochemical online sensors for real-time, cost-effective chlorine monitoring. The ERUN-SZ4-K6 is engineered to meet this demand with certified quality and industrial-grade durability.
Core Advantage: Electrochemical amperometric sensors eliminate reagent consumption, reduce maintenance costs, and provide continuous real-time data—while DPD methods require manual sampling, reagent refills, and produce chemical waste.
The DPD colorimetric method, while widely recognized as a laboratory standard, is inherently batch-based. Results take minutes to obtain, require constant reagent refills and pump maintenance, and are highly sensitive to water matrix interference such as turbidity and color. In contrast, the ERUN-SZ4-K6 uses a membrane-covered three-electrode amperometric system that measures chlorine concentration instantly through electrochemical oxidation-reduction reactions—no reagents, no waste, no waiting. Field DPD test kits are typically used where high accuracy is not required, making them unsuitable for critical continuous monitoring applications.
Certification Profile: The ERUN-SZ4-K6 is fully certified with CE, ISO 9001, RoHS, and SIL4—ensuring compliance with international quality, safety, environmental, and functional safety standards for global export.
CE certification confirms the analyzer meets EU health, safety, and environmental protection requirements, enabling seamless market access across Europe. ISO 9001 certification validates that the design, manufacturing, and quality control processes adhere to internationally recognized quality management standards. RoHS compliance guarantees the product is free from restricted hazardous substances, supporting environmentally responsible procurement. SIL4 (Safety Integrity Level 4) certification—the highest level of functional safety—ensures the analyzer performs reliably in safety-critical applications where measurement failure could have serious consequences. These certifications collectively provide buyers with documented assurance of product quality, safety, and regulatory compliance.
Technical Principle: The high-purity gold working electrode, combined with a reference electrode and counter electrode in a membrane-covered design, maintains stable potential through an integrated potentiostat—ensuring drift-free, accurate chlorine measurement.
The ERUN-SZ4-K6 employs a membrane-covered amperometric three-electrode system with a high-purity gold working electrode. An integrated high-precision potentiostat keeps the working electrode potential stable, allowing chlorine species (such as hypochlorous acid and hypochlorite ions) to undergo controlled oxidation-reduction reactions at the electrode surface. The resulting current follows Faraday's law, providing a direct quantitative relationship with chlorine concentration. The membrane protects the electrode from fouling by impurities in the water sample, extending maintenance intervals and suppressing zero drift. This design delivers a detection limit as low as 0.030 mg/L with a T90 response time of ≤90 seconds.
Key Parameters: Measurement range: 0-5/20 mg/L with 0.001 mg/L resolution, ±3% accuracy, RS485 MODBUS digital output, IP68 protection, and wide operating temperature range from -5°C to 45°C.
Parameter | Specification |
|---|---|
Measurement Parameters | Free chlorine, total chlorine, chlorine dioxide, ozone |
Electrode | Membrane-covered gold electrode |
Measurement Range | 0-5/20 mg/L |
Resolution | 0.001 mg/L |
Accuracy | ±3% (DPD comparison error ±10% or ±0.05 mg/L, whichever is greater) |
Repeatability | ±3% |
Detection Limit | 0.030 mg/L or lower |
Response Time | T90 ≤ 90s |
Measurement Method | Reagent-free, electrochemical, three-electrode amperometric system |
Calibration | Single-point or two-point calibration |
Temperature Range | -5 to 60°C (measurement); -5 to 45°C (operating) |
Pressure Range | <0.1 MPa |
Power Supply | DC 9-28V, 0.5W peak |
Digital Output | RS485 MODBUS protocol |
Analog Output | 4-20mA (optional) |
Protection Rating | IP68 |
Installation | Flow-through type |
Applicable Industries & Scenarios: The ERUN-SZ4-K6 is suitable for drinking water treatment, secondary water supply, swimming pools, medical water, industrial circulating cooling water, wastewater treatment, food and beverage processing, aquaculture, and pharmaceutical manufacturing.
In drinking water treatment plants, continuous free chlorine monitoring at outlets ensures compliance with WHO guidelines (recommending 0.2–0.5 mg/L for drinking water). For secondary water supply systems, simultaneous monitoring at tank outlets and user endpoints detects chlorine decay anomalies, guiding cleaning schedules and disinfection strategy adjustments. In industrial circulating cooling water, the analyzer helps prevent microbial growth and biofilm formation. The IP68-rated housing withstands harsh, humid environments from outdoor distribution points to industrial cooling towers. The dual RS485 digital and optional 4-20mA analog outputs enable seamless integration with existing PLCs, SCADA systems, and IoT platforms.
Cost-Effective Features: Zero reagent consumption, minimal maintenance (periodic membrane cleaning only), and 12-24 month service life make the ERUN-SZ4-K6 significantly more cost-effective than reagent-based DPD analyzers over time.
Traditional DPD analyzers require constant reagent refills, pump maintenance, and replacement parts, driving up operational costs. The ERUN-SZ4-K6 eliminates these expenses entirely—no chemical reagents, no waste disposal costs, no reagent degradation or batch-to-batch variability. The membrane-covered design protects the electrode from fouling, extending maintenance intervals. For facilities with multiple monitoring points, online analyzers enable centralized monitoring and data sharing, improving management efficiency. While the initial investment may be higher than test strips or simple electrodes, the long-term savings in labor, consumables, and improved process control deliver superior return on investment.
Enterprise Profile: Erun Environmental Protection (founded 2009, headquartered in Xi'an High-tech Industrial Development Zone) provides comprehensive analytical instrumentation solutions with a dedicated R&D, sales, and service team serving global clients including China National Petroleum, Sinopec, and China Aerospace.
With over a decade of experience in environmental monitoring instrumentation, Erun offers end-to-end support from product selection and system integration to remote training and maintenance guidance. The company's products serve diverse industries including petroleum, chemical, gas transmission, municipal, steel, fire protection, environmental protection, metallurgy, biochemical pharmaceuticals, military, energy power, and scientific research, with exports to Vietnam, Africa, and other regions. Free remote training is provided until users can operate the equipment proficiently and perform routine maintenance and troubleshooting.
Q: What is the difference between free chlorine and total chlorine?
A: Free chlorine is the active disinfectant that combats pathogens. Combined chlorine refers to weaker, longer-lasting chloramines. Total chlorine is their sum, critical for assessing overall disinfection efficacy.
Q: How often does the ERUN-SZ4-K6 sensor need calibration?
A: The ERUN-SZ4-K6 supports both single-point and two-point calibration methods. Calibration frequency depends on application and water quality conditions—typically monthly for critical applications or when accuracy verification indicates drift.
Q: Does the ERUN-SZ4-K6 work in high-salinity or high-turbidity water?
A: Yes. The membrane-covered design protects the electrode from fouling and interference from suspended solids, making it suitable for a wide range of water matrices including industrial circulating water and wastewater.
Q: What communication protocols does the analyzer support?
A: RS485 MODBUS protocol as standard, with 4-20mA analog output available as an option. This enables integration with most industrial control systems.
Q: Is the analyzer suitable for outdoor installation?
A: Yes. The IP68 protection rating ensures reliable operation in harsh, humid environments. The operating temperature range of -5°C to 45°C covers most outdoor conditions.
Erun Environmental Protection—providing reliable, certified water quality analysis solutions to industries worldwide since 2009.
