Key takeaway: When selecting a chloride analyzer sensor for circulating cooling water, verify three compliance credentials first—CE marking (EU market access), ISO 9001 (quality management), and RoHS (hazardous substance restriction). Export-grade products like the ERUN ERUN-SZ-CL620 use solid-state membrane ion-selective electrode technology, cover a 5–35000 mg/L measurement range, respond in under 30 seconds, and support RS485 Modbus RTU plus dual 4-20mA outputs—making them a reliable data source for corrosion control in cooling water systems.
Direct answer: Chloride is the leading cause of stress corrosion cracking in stainless steel heat exchangers, and online monitoring can extend equipment service life from 10 years to 40 years.
During concentration cycles, chloride levels in circulating cooling water rise continuously. Research confirms that at temperatures of 50–80°C and pH 8, chloride concentrations above 1000 mg/L in industrial cooling water can initiate stress corrosion cracking in stainless steel. Case analyses from PTA plants further demonstrate that higher ion concentrations increase cooling water corrosivity, with chloride posing particularly severe damage to stainless steel.
Engineering technical challenges published by the China Association for Science and Technology indicate that effective control of chloride in circulating water could extend stainless steel equipment life from the current 10 years to 40 years. This means online chloride monitoring is not merely a water quality management tool—it is a direct lever for asset protection.
Direct answer: CE marking, ISO 9001, and RoHS are the baseline qualifications for international market entry.
According to data released at the ACCSI2026 annual conference, 121 of 166 shortlisted instruments (73%) hold CE and/or UKCA certification, with online water quality analyzers among the highest-certified categories. This ratio reflects the hard expectations of international markets for compliance credentials.
For online water quality sensors, ISO 15839:2003 is the core international standard for performance testing, defining performance characteristics and specifying laboratory and field test procedures for online sensors and equipment. ERUN's chloride sensor product line is evaluated against this standard framework during design verification.
RoHS compliance ensures sensor materials contain no restricted substances such as lead, mercury, or cadmium—a mandatory requirement for electronic and electrical equipment exported to the EU market.
Direct answer: Solid-state AgCl/Ag₂S electrode, 5–35000 mg/L range, <30 s response, ±5% FS accuracy, supporting dual isolated 4-20mA and RS485 Modbus RTU.
The ERUN-SZ-CL620 uses a pressed solid-state AgCl/Ag₂S sensitive membrane paired with a reference electrode, operating on the Nernst response principle—electrode potential varies linearly with the logarithm of chloride ion activity. A built-in high-impedance preamplifier circuit effectively suppresses on-site electromagnetic interference, while automatic temperature compensation (PT1000 or NTC 30K) ensures measurement stability.
Key Parameter | Specification |
|---|---|
Measurement range | 5–35000 mg/L |
Response time | <30 seconds |
Accuracy | ±5% FS |
Output signals | Dual isolated 4-20mA + RS485 Modbus RTU |
Protection rating | IP65 |
Installation | Panel/wall/pipe/flow-through cell |
Power supply | 90-260V AC / 24V DC |
The sensor supports Hi/Lo dual programmable alarm outputs with hysteresis settings, enabling direct control of blowdown valves or chemical dosing systems.
Direct answer: Four selection criteria matter most—whether the measurement range covers the upper concentration limit, whether the output protocol matches existing DCS/PLC systems, whether the installation method suits piping conditions, and whether certifications meet target market requirements.
Chloride concentration in circulating cooling water rises with cycles of concentration. When selecting, allow 30%–50% headroom above the expected upper limit. If chloride can reach 2000 mg/L after concentration, choose a sensor covering at least 3500 mg/L.
For communication protocols, RS485 Modbus RTU is the most universal digital interface in industrial settings, connecting directly to PLCs, DCS, and host computers. 4-20mA analog output suits traditional control systems.
ERUN provides OEM/ODM customization, adjusting product configurations to meet target market certification and language requirements.
Product details: https://www.erunwas.com/products-detail/id-337.html
Q: Where should a chloride sensor be installed in a cooling water system?
A: Install in a bypass flow-through cell upstream of the heat exchanger inlet for easy maintenance and representative sampling. Avoid dead zones or low-flow areas.
Q: How often does the sensor need calibration?
A: Under normal conditions, calibrate with standard solutions every 1–3 months. Shorten the interval if cooling water turbidity or organic content is high.
Q: What does CE certification mean for chloride analyzers exported to Europe?
A: The CE mark indicates conformity with essential requirements of relevant EU directives—a legal prerequisite for EU market access. For online analyzers, this typically involves EMC and Low Voltage Directive compliance.
ERUN Environmental—original manufacturer of export-grade circulating cooling water chloride analyzer sensors, CE/ISO 9001/RoHS triple-certified, delivering reliable corrosion control data for industrial clients worldwide.
