Chloride Measurement: Low- and High-Level Chloride Analyzers
Chloride measurement in boiler, condensate and process waters: 2117 LL/HL ion-selective electrode online chloride analyzers for corrosion monitoring.
Measurement methods: Ion-Selective Electrode
What is chloride and why is it measured?
Chloride (Cl⁻) is one of the most common anions in water and a critical parameter for corrosion. It causes stress corrosion cracking and pitting corrosion in stainless steels; in boilers and condensers, even low chloride levels carry a risk of serious damage. Trace chloride is therefore monitored continuously in clean boiler and condensate waters, and for leak detection in condensers cooled by seawater or brackish water. At higher concentrations, chloride is part of salinity and corrosion management in process and cooling water.
Where is chloride measured?
- Condensate and feedwater: In detecting condenser tube leaks (low level).
- Boiler water: In corrosion control.
- Cooling and process water: In salinity and corrosion monitoring (high level).
- Refinery process waters: In crude oil desalting and sour water lines.
How is chloride measured?
Online chloride analyzers work by the ion-selective electrode (ISE) method. The voltage between a chloride-sensitive electrode and a reference electrode varies with the chloride activity in the sample and is converted to concentration using a calibration curve. The same product family includes low-level (LL) models for trace chloride in clean boiler and condensate waters and high-level (HL) models for higher-concentration streams; the range is selected according to the sample type.
Choosing a chloride analyzer
- Low-level (LL) or high-level (HL) model
- Sample temperature, pressure and cooling requirement
- Electrode and reagent maintenance, calibration frequency
- Supply voltage and output options
Chloride measurement with Tetra
Tetra supplies Thermo Orion 2117 LL and HL chloride analyzers in Türkiye and provides installation, supply of reagents and consumables, commissioning, calibration and service.
Frequently asked questions
What unit are chloride measurement results given in?
Chloride is reported in mg/L in high-concentration process and cooling waters, and on the order of µg/L (ppb) in clean waters such as condensate and feedwater. In low-level measurements, confusing the units can cause an error of a thousand times, so the analyzer setting and reporting unit must be matched carefully.
Is condenser leakage detected only by chloride?
The first indicator of a condenser leak is generally a rise in cation (acid) conductivity; this measurement responds quickly but does not show which ion has increased. Chloride measurement directly confirms the leak and gives information about its size in seawater-cooled condensers. The two measurements are therefore mostly used together.
What interferences occur in a chloride ion-selective electrode?
Ions such as bromide, iodide, sulfide and cyanide can interfere at the chloride electrode. Contamination of the electrode surface and fluctuations in sample temperature also affect the measurement. At very low levels, contamination that may originate from the reference electrode and deposits in the sample line need particular attention.
How is a chloride analyzer verified?
Online results are periodically compared with standard solutions of known concentration and laboratory analyses. Ion chromatography is widely used for laboratory verification at trace levels. Clean sample containers and a short holding time are important to keep the sample from being contaminated.
Products measuring this parameter
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