Oil Trace Moisture Tester
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20+
years
Goldhome has specialized in the production and manufacturing of Oil Trace Moisture Tester for 20 years
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patents
With 35 patents, Goldhome keeps innovating and providing advanced, reliable power testing equipment.
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Singapore, Malaysia,UAE, Saudi Arabia, South Africa, Nigeria, Germany, Poland, Brazil,the USA,India,the UK, Switzerland, Russia.
The oil moisture analyzer is a specialized instrument designed to accurately measure trace moisture content in oils such as transformer oil, lubricating oil, and hydraulic oil. In industries such as power generation, petroleum, and chemicals, it serves as a critical tool for ensuring safe equipment operation and quality control.
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Transformer oil plays a critical role in both insulation and heat dissipation within transformers. Moisture is the “natural enemy” of transformer oil:
- Reduced insulation performance: Even trace amounts of moisture in the oil can significantly reduce its dielectric strength, potentially leading to internal breakdowns and short circuits.
- Accelerates oil degradation: Moisture accelerates the oxidation of transformer oil, producing acidic substances and sludge, which further impair heat dissipation and insulation.
- Threatens equipment safety: Declining insulation performance and oil degradation greatly increase the risk of transformer failures and shorten its service life.
Click New:Insulating Oil Moisture Testing: Best Practices for Power Transformer Maintenance
The vast majority of high-precision oil trace moisture analyzers are based on Karl Fischer coulometric titration, which is internationally recognized as one of the most reliable methods for measuring trace moisture.
- Chemical Reaction: The oil sample is injected into an electrolytic cell containing a specific chemical reagent (Karl Fischer reagent). The water in the oil sample undergoes a precise 1:1 chemical reaction with the reagent.
- Electrolysis and Electric Charge: Through the electrochemical reaction, the instrument continuously generates an amount of iodine equal to the amount of water consumed. According to Faraday’s law of electrolysis, the electric charge consumed during electrolysis is directly proportional to the amount of iodine produced, and thus also directly proportional to the water content.
- Automatic Calculation: By precisely measuring the electrical charge consumed throughout the reaction, the instrument automatically calculates the specific moisture content in the oil sample, typically displayed in parts per million (ppm) or as a percentage (%).
Test Procedure
1) Reagent System
The instrument uses Karl Fischer reagent internally, with the following main components:
Iodine (I₂)
Sulfur dioxide (SO₂)
Pyridine / Imidazole (buffer)
Methanol (solvent)
(2) Iodine Production via Electrolysis
The instrument contains a pair of electrolytic electrodes (anode + cathode). When an electric current is applied, a reaction occurs at the anode: 2I⁻ → I₂ + 2e⁻, which means that an electric current is used to electrolyze iodide ions into iodine molecules.
H2O+I2+SO2+3C5H5N+CH3OH=product
(3) Quantitative Reaction Between Iodine and Water
The generated iodine immediately undergoes a Karl Fischer reaction with the water in the oil sample: The key rule for the reaction products is that 1 molecule of water exactly consumes 1 molecule of iodine.
(4) End-point Detection
The instrument also includes a pair of indicator electrodes to detect whether there is any excess iodine remaining in the solution.
When water is present: Iodine is consumed as soon as it is produced, and there is no free iodine in the solution.
When the water has reacted completely: Free iodine suddenly appears, and the indicator electrodes detect a sudden change in the polarization current → The end-point is reached, and electrolysis stops.
(5) Calculating Water Volume Based on Electric Charge
According to Faraday’s law of electrolysis: the amount of charge consumed is directly proportional to the amount of iodine produced, and iodine reacts with water in a strict 1:1 ratio.
Final calculation formula: Water content(mg)
Q: Total charge consumed during electrolysis (coulombs)
M: Molar mass of water
F: Faraday’s constant
Main Features
High-Precision Measurement
Utilizing the Karl Fischer coulometric method, this instrument offers high sensitivity capable of detecting trace moisture at the microgram level. Measurement results are stable and reliable, meeting the high-precision testing requirements of the power and petrochemical industries.
Fast Measurement Speed
A single test typically takes 1 to 3 minutes to complete. The instrument automatically determines the endpoint, eliminating the need for manual calculations, making it suitable for on-site batch testing.
Simple Operation and High Automation
Features a large English-language display, one-button test initiation, and automatic electrolysis, balancing, calculation, and result display (ppm, mg/L, μg, etc.).
Strong Interference Resistance
Unaffected by sample color, impurities, or viscosity; suitable for transformer oil, lubricating oil, fire-resistant oil, and other applications.
Data Storage and Printing Capabilities
Can store large amounts of historical data; supports USB export and direct printing via the built-in printer, facilitating archiving and traceability.
Excellent Environmental Adaptability
Features a built-in desiccant tube and sealed design to minimize interference from atmospheric moisture, making it suitable for use in laboratories and on-site at substations.
Safe, Eco-Friendly, and Easy to Maintain
Uses minimal reagents and produces little waste liquid. The simple electrolyte cell structure facilitates cleaning and maintenance, resulting in low long-term operating costs.
Compliant with National and Industry Standards
Meets the requirements of standards such as GB/T 7600, DL/T 596, and IEC 60763, making it suitable for oil quality monitoring, acceptance testing, and annual inspections.
Compact Size and High Portability
The portable model is lightweight and battery-powered, enabling testing in the field, at job sites, and in substations without access to power sources.
Self-Diagnostic and Protection Features
Features automatic alerts for electrode abnormalities, reagent expiration, and balance timeout, ensuring more stable and safe operation.
Specific Categories
I. Classification by Measurement Principle
1. Karl Fischer Coulometric Moisture Analyzer (Electrochemical Method)
Currently the mainstream choice with the highest accuracy; standard equipment in the power industry
Suitable for laboratories, high-precision testing, and issuing formal reports
Measurement range: 1 ppm to 100% H₂O
2. Karl Fischer Volumetric Moisture Analyzer
Suitable for samples with high moisture content (percent level)
Less commonly used in oil moisture testing; primarily used for chemical raw materials
3. Capacitance / Dielectric Constant Method Moisture Analyzer
Fast, portable, and inexpensive
Lower accuracy; primarily used for rapid on-site screening
Cannot be used as a basis for arbitration or acceptance
4. Infrared Spectroscopy Moisture Analyzer
New online, maintenance-free
Primarily used in online monitoring systems; rarely seen in laboratories
II. Classification by Application
1. Laboratory Benchtop Oil Moisture Analyzer
Large size, high accuracy, full functionality
Suitable for laboratories and quality inspection centers
2. Portable Oil Moisture Analyzer
Lightweight, rechargeable, suitable for outdoor use
Suitable for on-site use at substations, routine inspections, and emergency repairs
3. Online Oil Moisture Monitor
Installed directly on the transformer body
Provides 24-hour continuous monitoring of moisture changes and real-time data upload
III. Classification by Automation Level
1. Manual Sampling Type
Manual oil sample injection; simple operation
Low cost; suitable for general organizations
2. Fully Automatic Type
Automatic sampling, automatic cleaning, and automatic waste disposal
Suitable for large sample volumes and third-party testing institutions
IV. Classification by Applicable Oil Samples
Insulating Oil Moisture Analyzer (Transformer Oil, Switchgear Oil)
Fire-Resistant Oil Moisture Analyzer
Lubricating Oil / Hydraulic Oil Moisture Analyzer
The operating principles are generally the same, with only slight differences in the sampling system and parameters
Operation Steps
I. Pre-Test Preparation
Instrument Check
Check that the level of the Karl Fischer reagent in the cell is normal, and ensure there is no cloudiness or discoloration.
Check whether the desiccant in the desiccator has changed color; if it has expired, replace it.
Turn on the instrument; it will automatically enter the equilibration phase. Wait until drift stabilizes.
Sample Preparation
Ensure the sample vial is tightly sealed to prevent moisture from the air from entering.
Shake the oil sample well, then let it stand to remove air bubbles.
Prepare a 1 mL or 5 mL syringe with a needle.
Environmental Requirements
Avoid operating in humid, windy, or dusty environments.
Perform the injection quickly to minimize interference from atmospheric moisture.
II. Operating Procedures
Instrument Standby
Injection may only be performed after the display shows **“Balanced”** and **“Drift Normal”**.
Injection
Draw an appropriate amount of oil sample (typically 0.5 mL to 1 mL) using a syringe.
Expel any air bubbles and record the precise injection volume.
Quickly pierce the rubber seal at the injection port and inject the oil sample into the electrolytic cell.
Start Measurement
Enter the sample volume (by volume or mass).
Press the “Start/Test” button; the instrument will automatically perform electrolysis and titration.
Monitor changes in the electrolysis current during the process; the instrument will automatically stop upon reaching the endpoint.
Read Results
The instrument automatically calculates and displays:
Moisture content: μg (micrograms of water)
Concentration: ppm / mg/kg / mg/L
You may choose to save data or print a report.
Test Completion
For continuous testing, you can inject another sample immediately.
After testing, close the sample port and keep the instrument sealed to prevent moisture absorption.
III. Post-Test Maintenance
When not in use for an extended period, seal the electrolytic cell and cover the sample port.
Replace the Karl Fischer reagent and desiccant regularly.
Clean the syringe to avoid cross-contamination.
Export and archive data, and complete the test record according to established protocols.
1. Power Systems
- Moisture detection in transformer oil, instrument transformer oil, circuit breaker oil, and GIS insulating oil
- On-site inspections at substations, new oil acceptance testing, overhaul testing, and preventive testing
- Essential for power grid companies, power plants, electric power research institutes, and power maintenance companies
2. Petrochemical and Lubricant Industries
- Quality testing of transformer oil, turbine oil, lubricating oil, hydraulic oil, heat transfer oil, etc.
- Factory acceptance testing at refineries and lubricant plants
- Quality monitoring during oil storage and transportation
3. Metallurgy, Mining, and Machinery Manufacturing
- Moisture monitoring in lubricants for large motors, gearboxes, and hydraulic systems
- Prevents equipment corrosion, seizing, and lubrication failure
- Operational and maintenance testing for steel mills, cement plants, and mining equipment
4. Rail Transit & Wind Power
- Trace moisture detection in traction transformer oil for high-speed rail and metro systems
- Moisture monitoring in gearbox oil and substation transformer insulating oil for wind turbines
5. Third-Party Testing and Research Institutions
- Arbitration testing by Quality Inspection Institutes, Metrology Institutes, and third-party laboratories
- Research and testing on oil performance at universities and research institutes
6. Other Industrial Sectors
- Testing of hydraulic oil and insulating oil for marine and aviation applications
- Moisture monitoring in lubricating oil for industrial equipment such as injection molding and die-casting machines
Famous Brands
International Brands
1. Mitsubishi Chemical (MITSUBISHI, Japan)
- Representative Models: CA-200, CA-31, KF-200
- Features: High precision, excellent stability, good compatibility with reagents; mainstream choice for power and petrochemical laboratories
2. Mettler Toledo (METTLER TOLEDO, Switzerland)
- Models: C30S, C20S, DL31
- Positioning: High-end laboratories, arbitration testing, accuracy ±1 μg
3. Metrohm (Metrohm, Switzerland)
- Models: 899 Coulometer, 756 KF
- Features: Classic coulometric method, strong interference resistance, suitable for high-viscosity oils
4. Siemens (Germany)
- Model: Sitrans WB350 (online)
- Target Market: Online trace moisture monitoring for transformers, smart grids
Domestic Brands
1. Goldhome Hipot (Wuhan)
Core Model: HM401 Insulating Oil Trace Moisture Analyzer
Target Market: Dedicated to power systems; on-site and laboratory testing of transformer oil / insulating oil
Features:
Karl Fischer coulometric method, 32-bit CPU, 7-inch touchscreen
Automatic drift compensation, electromagnetic interference resistance (suitable for substations)
Built-in power industry standards (GB/T 7600, DL/T 5102)
Portable / desktop options available; data storage / printing / export
2. Delite (Beijing)
Model: A1070, A1071
Application: General-purpose for petrochemical and power industries, fully automatic, large-screen touchscreen
3. Huace Testing (Huayi)
Models: HC-306, WS-2
Features: Commonly used for third-party testing, stable data
4. Shanghai Precision Science / Leizhi
Models: ZDY-501, KLS-706
Target Market: Universities / Basic laboratories, economical and practical
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FAQ
Q: 1. What is an oil trace moisture analyzer?
A: An oil trace moisture analyzer is primarily used to measure trace moisture content in oils such as transformer oil, insulating oil, and lubricating oil. It typically employs the Karl Fischer coulometric method, with results displayed in ppm or mg/L. It is a critical instrument for insulation safety testing in power and petrochemical equipment.
Q: 2. What principle does an oil trace moisture analyzer use?
A: The mainstream method is the Karl Fischer coulometric titration (electrochemical method).
Iodine is generated through electrolysis and undergoes a quantitative chemical reaction with the moisture in the oil. The moisture content is calculated based on the electrical charge consumed. This method offers high precision and good repeatability, and complies with national standards and power industry standards.
Q: 3. What types of oil samples can the instrument test?
A: ● Transformer insulating oil
● Instrument transformer oil, switchgear oil, GIS insulating oil
● Fire-resistant oil
● Lubricating oil, hydraulic oil, turbine oil
● Certain chemical solvents, paraffin oil, etc.
Q: 4. What are the measurement range and accuracy?
A: Typical specifications:
● Measurement range: 0.1 μg to 100 mg H₂O
● Moisture content: 1 ppm to 100%
● Accuracy: ±2 μg or ±3% of reading
● Resolution: 0.1 μg / 0.1 ppm
Q: 5. How long does a single test take?
A: Generally 1–3 minutes per test.
The instrument automatically balances, titrates, and determines the endpoint, requiring no manual supervision.
Q: 6. Does the instrument require reagents? How long do the reagents last?
A: It requires Karl Fischer electrolyte (specific to the coulometric method).
Under normal use, one bottle of reagent can test hundreds of samples, depending on the sample’s moisture content and sample volume.
Q: 7. Does the instrument require regular calibration?
A: ● Coulometric instruments generally do not require frequent calibration; they offer high stability based on Faraday’s law.
● Accuracy verification can be performed using standard water reagents (distilled water or standard water samples), and it is recommended to do so every 3–6 months.
Q: 8. What is the typical sample volume?
A: A common sample volume is 0.5 mL to 1 mL of oil.
The sample volume should be fine-tuned based on the oil’s moisture content: use a smaller volume for high moisture content and a slightly larger volume for low moisture content.
Q: 9. What causes results to be too high or too low?
A: Common causes:
● Bubbles during injection → Results are too high
● Sample bottle not sealed tightly, allowing moisture from the air to enter → Results are too high
● Reagent expiration or significant balance drift → Low or unstable results
● Too slow injection rate, allowing ambient moisture to enter → High results
● Poor seal in the electrolytic cell or expired desiccant → Significant drift
Q: 10. Can the instrument be used on-site at a substation?
A: Yes.The portable model supports rechargeable battery power and is resistant to electromagnetic interference, making it suitable for on-site inspections, emergency repairs, and preventive testing.
Q: 11. Can data be saved, printed, or exported?
A: Yes:
● Built-in storage for hundreds of sets of historical data
● Built-in thermal printer for direct report printing
● USB interface for exporting data to a computer
Q: 12. Which standards does it comply with?
A: ● GB/T 7600 Method for Determining Water Content in Transformer Oil in Service
● DL/T 596 Code for Preventive Testing of Power Equipment
● IEC 60814, ASTM D1533, ASTM D6304, and other international standards
Q: 13. What is the difference between the benchtop and portable models?
A: Benchtop: Higher accuracy and more comprehensive features, suitable for laboratories
Portable: Compact size, battery-powered, suitable for rapid on-site testing
Q: 14. Is instrument maintenance difficult?
A: Maintenance is simple:
Replace the desiccant in the drying tube periodically
Replace the electrolyte when the reagent becomes cloudy or equilibrium is difficult to achieve
Keep the electrolyte cell sealed to prevent dust and excessive water ingress
Clean the syringe to prevent cross-contamination
Q: 15. Are oil trace moisture analyzers and oil dielectric loss testers the same?
A: No, they are different:
Oil trace moisture analyzer: Measures the moisture content in oil
Oil dielectric loss tester: Measures the dielectric loss, volume resistivity, and breakdown voltage of oil
Both are essential for oil testing and serve complementary purposes.
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