Rapid viscosity tester(RVA) Operation and Usage Guide:
1、 Preparation before operation
Instrument inspection and installation
Ensure that all components of the instrument (such as the rotor, mixer, sample cylinder) are intact and the power cord is securely connected.
Place the instrument on a stable, vibration free horizontal table and adjust it to a horizontal position using a horizontal bubble and adjusting feet.
Select the appropriate rotor (such as 1 # -4 # standard rotor) based on the viscosity range of the sample, and install it onto the lower connecting rod of the instrument. Gently tighten the fixing nut with a wrench.
Sample preparation
The sample should be uniform, stable, and free of particle impurities. For high viscosity samples, diluents can be added to reduce viscosity.
Accurately weigh the sample mass using a balance (error ≤ 0.01g) and record the amount of water added (error ≤ 0.01mL). For example, wheat flour testing requires weighing 2-3g of the sample and adding water on a 14% wet basis.
Pour the sample into a clean test tube or beaker and gently stir with a stirring rod until fully mixed.
environmental control
The viscosity is significantly affected by temperature, and the sample needs to be placed in a constant temperature water bath to stabilize the temperature at the required test value (such as 25 ℃ or 140 ℃), with temperature fluctuations controlled within ± 0.1 ℃.
If the sample contains bubbles, degassing treatment (such as standing or ultrasonic degassing) is required.
IIRapid viscosity testerOperation steps
Power on preheating
Connect the power supply, turn on the instrument power switch, and preheat for 15-30 minutes (if RVA requires preheating for 30 minutes) to ensure the stability of internal electronic components.
Parameter Settings
Select the measurement mode (such as mixing, heating, cooling cycle) and temperature program based on the properties of the sample.
Refer to the "rotor speed range" comparison table in the instrument manual, select the appropriate rotor and speed combination, and display the torque percentage (% TORQUE) between 10% -100% (ideal range 20% -80%).
Set the speed (such as 6rpm, 12rpm, 30rpm, 60rpm, etc.) and temperature curve (such as heating rate of 14 ℃/min).
Sample loading
Place the mixer in the sample cylinder and vigorously stir it up and down 10 times to ensure even distribution of the sample.
Insert the sample cylinder into the instrument and press the tower cap to start the measurement cycle. For a digital viscometer, it is necessary to slowly lower the rotor and immerse it into the sample. The rotor groove should be immersed 4-6mm below the liquid level to avoid touching the container wall or bottom.
data collection
After starting the measurement, observe and record the data. RVA can display gelatinization temperature, peak viscosity, peak time, attenuation value in real time*LowParameters such as viscosity, rebound value, and final viscosity.
For non Newtonian fluids, multiple speed measurements can be selected under the same rotor to observe whether the viscosity value changes with speed.
After the measurement is completed, the instrument automatically calculates and displays the results. If further analysis is required, data can be exported to a computer.
End operation
After the measurement is completed, turn off the instrument power, remove the sample cylinder or rotor, and store the sample properly.
Immediately wipe the rotor and protective frame with a suitable solvent (such as alcohol, acetone) and a soft cloth to avoid residue affecting the next measurement. For samples that are difficult to clean, the rotor can be soaked in a solvent.
3、 Precautions
Operational Security
To avoid the dangers of electric shock, burns, etc., wear protective gloves and goggles during operation.
It is strictly prohibited to immerse the rotor into the sample while it is rotating, especially for high viscosity samples, to avoid damaging the internal structure of the instrument.
instrument maintenance
Regularly use standard oil calibration instruments to ensure measurement accuracy.
Keep the rotor and measuring container clean to prevent foreign objects from entering the interior of the instrument.
When not in use for a long time, place the instrument in a dry and ventilated environment and maintain it regularly.
error control
Ensure sample quality and accurate water addition to avoid viscosity deviation caused by concentration errors.
Avoid scratching the sample cylinder with the mixer, otherwise it may cause data fluctuations.
To prevent cavitation (bubbles generated on the back of the agitator blade), it can be solved by high shear force or adjusting the speed.
exception handling
If the instrument displays abnormalities or data fluctuates greatly, stop using it immediately and contact professional maintenance personnel.
When the measurement results are inaccurate, check the sample distribution, rotor immersion depth, and whether there are impurities in the container.