The automatic interfacial tension tester is a precision instrument used to measure the interfacial tension (or surface tension) of liquids. Its usage rules should take into account operational standards, accuracy assurance, and equipment maintenance. The following is a brief introduction to the core points:
1、 Preparation before use
Environmental Requirements
The instrument should be placed on a stable and horizontal table to avoid vibration; The laboratory temperature should be kept stable (usually recommended at 20 ± 2 ℃), humidity should be ≤ 80%, and kept away from heat sources and strong airflow (such as air conditioning vents).
Before starting up, check if the power supply voltage matches (usually 220V ± 10%) and ensure good grounding.
Sample and instrument preparation
The tested liquid should be uniform, free of bubbles and impurities, and filtered if necessary (such as using a 0.45 μ m filter membrane); The sample temperature should be consistent with the laboratory environment to avoid temperature differences affecting measurement accuracy.
Cleaning accessories: Platinum rings (or platinum plates) and glassware (such as sample cups) should be wiped with acetone or ethanol, rinsed with distilled water, and dried to avoid touching the contact surface (can be operated with tweezers).
2、 Standard operating procedures
Power on and calibration
Connect the power supply, start the instrument, and preheat for 10-15 minutes (ensure sensor stability); Calibrate according to the instructions (such as using standard weights or standard solutions with known tension), and record and archive the calibration data.
Sample measurement
Platinum Ring Method (applicable to interfacial tension):
Place the sample cup on the instrument lifting platform, pour in the measured liquid (about 2/3 of the cup depth), adjust the lifting platform so that the platinum ring is immersed 2-3mm below the liquid level.
Start the instrument, the program automatically lifts the sample cup, and when the platinum ring is detached from the liquid surface, the instrument records the maximum tensile force value, which is automatically converted into interfacial tension (unit: mN/m) by the system.
Platinum plate method (applicable to surface tension):
The platinum plate is vertically suspended below the sensor, and its position is adjusted to make contact with the liquid surface. The instrument calculates the surface tension by measuring the buoyancy received by the plate.
Data recording and processing
Repeat each measurement 3-5 times and take the average value (the deviation of a single measurement should be ≤ 0.5%); Record measurement temperature, sample name, batch number, and other information to avoid confusion.
If the data is abnormal (such as excessive fluctuations), it is necessary to check whether the sample is contaminated, whether the platinum ring is deformed, or recalibrate the instrument.
3、 Safety and Precautions
Operational Security
If the tested liquid is corrosive or toxic, it should be operated in a fume hood and protective equipment such as gloves and goggles should be worn.
Avoid pulling the platinum ring/plate to prevent deformation (which can cause measurement errors). If oxidation or contamination is found on the surface of the ring/plate, it should be soaked in dilute nitric acid and cleaned and dried.
Prohibited acts
It is strictly prohibited to forcefully move the sample cup or touch the sensor while the instrument is running; Do not measure high temperatures (exceeding the rated range of the instrument, such as>100 ℃) or highly corrosive liquids to avoid damaging accessories.