1Automatic Ubbelohde viscometerCalibration process: Accurate guarantee of measurement reliability

Appearance and Initial Inspection

Structural integrity: Check the appearance of the viscometer to confirm that there are no cracks or scratches, the measuring tube, vent tube, and intake tube are parallel and perpendicular, and the inner wall of the capillary tube is smooth and free of foreign objects.

Environmental adaptation: Place the device on an independent experimental platform, away from vibration sources (such as centrifuges), equipped with shock pads, and control the laboratory temperature at 20-25 ℃ and humidity at 40% -60% to prevent glass components from cracking due to sudden changes in temperature and humidity.

Selection and treatment of standard solution

Standard liquid requirements: Select two different viscosity standard liquids (with a difference in kinematic viscosity of ≥ 20%), with a flow time of ≥ 200 seconds to ensure measurement stability.

Preprocessing: Place the standard solution in a constant temperature water bath to balance the temperature, filter out impurities before use, and avoid particle interference.

Liquid filling and constant temperature treatment

Bubble free liquid filling: Slowly inhale the standard liquid into the upper storage ball with a syringe, gently tap the tube wall to eliminate bubbles and prevent flow time deviation.

Constant temperature control: Fix the viscometer vertically in a constant temperature water bath, with the liquid level above ball C, and maintain constant temperature for 15-30 minutes to ensure temperature uniformity (≤ 0.05 ℃).

Timing and repeated measurements

Measurement of outflow time: Connect a latex tube at ports 1 and 3, clamp port 3, extract air to raise the liquid level to the middle of ball C, and release it. Use a stopwatch to record the time when the liquid level flows through the scale line.

Repeatability requirement: Each standard solution should be measured at least 4 times, with a difference of ≤ 0.1 seconds between the two measurements. The average value should be taken as the outflow time.

Constant calculation and verification

Formula calculation: According to the formula(C is the constant of the viscometer, v is the kinematic viscosity of the standard liquid, and t is the outflow time) Calculate the constant.

Multi liquid verification: Repeat the above steps with the second standard solution, and take the average of the two calculation results as the final constant to ensure calibration accuracy.

2、 Maintenance points: key measures to extend equipment lifespan

Instant cleaning and drying

Sample residue removal: Immediately rinse the sample chamber and capillary with anhydrous ethanol or specialized cleaning solution after each test to prevent blockage of the channel after the polymer or high concentration salt solution dries.

High pressure flushing: For stubborn residues, use a syringe or high-pressure nitrogen gas (pressure ≤ 0.2MPa) to reverse flush the capillary tube to ensure smooth flow.

Drying treatment: After cleaning, dry with dry nitrogen gas or place in a 60 ℃ oven for drying (to avoid glass deformation caused by high temperature).

Thermostatic bath maintenance

Regular water change: Replace the deionized water in the constant temperature bath every month to prevent the growth of algae or bacteria from affecting temperature uniformity.

Scale removal treatment: If hard water is used, add 5% citric acid solution every 3 months for cyclic cleaning to remove scale and thoroughly rinse off.

Temperature calibration: Use a high-precision platinum resistance thermometer (accuracy ± 0.01 ℃) to calibrate the constant temperature bath, and adjust the parameters when the error exceeds ± 0.1 ℃.

Component replacement and inspection

Sealing ring replacement: Check the sealing ring at the sample chamber and capillary connection every 6-12 months. If aging, cracking, or deformation occurs, replace it immediately. Choose corrosion-resistant materials according to the solvent type (such as fluororubber for organic solvents and silicone rubber for aqueous solutions).

Temperature sensor calibration: Calibrate every 2 years. If the response is slow or the reading drifts, a new sensor needs to be replaced.

Peristaltic pump tube inspection: Check the wear of the pump tube every 3 months. If there are cracks or decreased elasticity, replace it in a timely manner to avoid unstable flow.

Operating standards and dust prevention

Pipette accuracy: Use an A-grade pipette (error ≤± 0.01mL) to load the sample, avoiding excessive overflow and corrosion of the equipment.

Bubble exclusion: After loading the sample, gently tap the tube wall or use a degassing device to remove bubbles to prevent them from interfering with the measurement of outflow time.

Dust protection: Cover with a transparent dust cover when not in use to prevent dust from entering the sample chamber or capillary tube.

IIIAutomatic Ubbelohde viscometerTroubleshooting and optimization suggestions

Common fault handling

Unstable reading: Check if the device is placed on a stable surface, eliminate power interference, and if the problem persists, contact the supplier or professional technician for repair.

Temperature deviation: Verify the actual temperature with a thermometer, adjust the instrument temperature calibration parameters, and ensure the temperature uniformity of the constant temperature bath (≤ 0.05 ℃).

Liquid leakage: Stop using immediately, check the sealing performance, replace the sealing ring or perform repairs.

Long term stability optimization

Maintenance log: Record the time of each operation, replacement of parts, and calibration data, providing a basis for equipment lifecycle management.

Software calibration: By inputting calibration coefficients through the device's accompanying software, the system clock deviation is corrected to ensure accurate timing function (error ≤ 0.1 seconds).

Environmental control: Wrap insulation material around the outer wall of the constant temperature bath to reduce the impact of external temperature fluctuations on measurement results.