– Foreword –
Across numerous industries including petrochemicals, power generation, pharmaceuticals, and food processing, the presence of trace moisture acts as an invisible time bomb, capable of significantly impacting product quality, equipment longevity, and even production safety. The urgent need to rapidly and accurately determine trace moisture levels in liquids, solids, and gases has become a critical requirement for both laboratories and production sites.
Part One: Measurement Principles and Processes
The trace moisture analyser, with its exceptional performance, has become an all-rounder for moisture determination across liquids, solids, and gases. The following outlines its specific measurement principles and procedures:
- Liquid Sample Analysis
Liquid samples are analysed using the classical Karl Fischer coulometric titration method. Upon introduction into the electrolytic cell, the water content reacts with iodine (I₂) and sulphur dioxide (SO₂) in the electrolyte solution: H₂O + I₂ + SO₂ + 3C₅H₅N → 2C₅H₅N·HI + C₅H₅N·SO₃. The instrument generates iodine through electrolysis. According to Faraday’s law, the electrical charge consumed during electrolysis is directly proportional to the amount of iodine produced. Since the amount of iodine produced equals the amount of water present in the sample, the water content is precisely calculated.
During operation, first draw an appropriate volume of liquid sample using a clean, dry syringe, taking care to expel any air from the syringe to avoid affecting the measurement results. Next, slowly insert the syringe needle into the electrolyte cell’s inlet, ensuring the needle is fully immersed in the electrolyte. Then, slowly inject the sample, preventing splashing or contact with the electrodes. Finally, the instrument automatically performs the measurement, with the LCD screen displaying real-time current changes and calculated moisture content results, ensuring rapid and efficient operation.
- Solid Sample Analysis
Solid analysis incorporates a cartridge sampler. After weighing the solid sample, place it into a specially designed sample vial and seal it before positioning within the cartridge furnace. Dried, filtered carrier gas (such as nitrogen) is passed through the sample vial at a constant flow rate, conveying the moisture within the sample into the titration cell. Within the titration cell, the moisture reacts with the Karl Fischer reagent. The instrument generates iodine via electrolysis and calculates the moisture content based on Faraday’s law. The design of the Karl Fischer furnace effectively shields the sample from external environmental interference, ensuring the accuracy and stability of the measurement results.
The specific procedure is as follows: Accurately weigh a specific quantity of solid sample using a precision balance. Place the sample into a clean, dry vial and seal it immediately to prevent moisture absorption from the air. Insert the sealed sample vial into the heating chamber of the Karl Fischer furnace. Set the appropriate heating temperature and carrier gas flow rate according to the sample’s properties. For instance, samples with good thermal stability may tolerate higher temperatures to accelerate moisture volatilisation, whereas heat-sensitive samples require lower temperatures. Activate the carrier gas supply system, allowing the gas to pass sequentially through a drying tube and filter to remove moisture and impurities, ensuring the gas entering the vial is pure and dry. Finally, initiate the Karl Fischer titrator and instrument measurement programme. The carrier gas transports moisture from the sample to the titration cell, where the instrument automatically performs titration and calculations, ultimately displaying the moisture content result on the liquid crystal display.
- Gas Sample Analysis
For gaseous samples, the instrument introduces the gas into a titration cell containing Karl Fischer reagent, where the moisture in the gas reacts with the reagent. The instrument calculates the moisture content in the gas based on the electrical charge consumed during electrolysis, in accordance with Faraday’s Law. This method offers high sensitivity and a broad measurement range, meeting the moisture determination requirements for various gas samples.
During operation, connect the gas sample source to the instrument’s inlet using a dedicated gas connection tube, ensuring a tight seal to prevent gas leakage. A gas flow meter precisely regulates the flow rate into the titration cell, typically recommended between 50–500 mL/min to ensure measurement accuracy and stability. Upon initiating the instrument’s measurement programme, gas slowly enters the titration cell where it reacts with the reagent. The instrument continuously monitors changes in the electrolytic current, calculating and displaying the moisture content within the gas.
Part Two: Introduction to Cartridge Samplers
- Working Principle
The sample is weighed directly into the sample vial, sealed, and placed in the cartridge insertion chamber. The carrier gas, after drying and filtration, transports moisture from the sample into the titration cell. The moisture reacts with the reagent, forming iodine at the anode via electrolysis. The generated iodine, according to Faraday’s Law, is directly proportional to the amount of charge. The moles of iodine participating in the reaction equal the moles of water present. When the sample is introduced into the electrolyte, its moisture content reacts. The instrument measures the iodine consumption during this reaction. This consumption is then converted into the moisture content via the electrical charge required to electrolytically produce an equivalent amount of iodine. The calculated moisture value is displayed directly on the liquid crystal display.
- Functional Features
PID temperature control ensures high-precision regulation
Integrated control unit for temperature regulation, cooling, and gas pump operation, offering convenience and safety
Carrier gas and moisture from the sample are conveyed into the electrolytic cell via a heated tube, preventing ambient temperature from affecting sample’s moisture content
High-precision flow meter ensures stable and accurate gas flow
– Summary –
Whether dealing with liquid, solid, or gaseous samples, the precise determination of moisture content is a critical step in ensuring production quality and advancing scientific research. The Times New Dimension Trace Moisture Analyser, with its advanced measurement principles, extensive functional features, and broad application scope, has become the ideal choice for moisture determination across diverse industries. Moving forward, TIMEPOWER will remain steadfastly focused on product innovation, guided by market demands and centred on user experience. We will continuously refine product performance to deliver superior, high-efficiency products and solutions, empowering industries to advance relentlessly on their journey towards excellence.