The same is a viscometer, what is the difference between an Ubbelohde viscometer and an Ostwald viscometer?

The same is a viscometer, what is the difference between an Ubbelohde viscometer and an Ostwald viscometer? Ubbelohde viscometer and Ostwald viscometer are two common types of viscometers, so what are the differences between them? Let’s find out with me below
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1.
Different principles Ubbelohde viscometer: When the fluid flows under the action of external force, there is a tangential internal friction force between the flowing liquid layers, if the liquid is to pass through the tube
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When the flow rate is low, the liquid in the pipe advances along a straight line parallel to the pipe wall, and the liquid close to the pipe wall is actually static.
The farther the distance from the pipe wall, the greater the flow speed
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Austenitic viscometer: U-shaped glass tube with two bulbs, I bulbs have notches a and b on the top and bottom, and a section of capillary tube below it
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When in use, two different liquids with the same volume flow through the same capillary tube under the bubble I respectively.
Due to the different viscosity coefficients of the two liquids, the time to run out is different
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When measuring, water is generally used as the standard liquid
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First inject water into bubble II, then inhale into bubble I, and make the water surface above the notch a
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Due to the action of gravity, water flows into the II bubble through the capillary.
When the water surface drops from the notch a to the notch b, record the time t1, and then replace the same volume of the liquid to be tested in the II bubble, using the same method The corresponding time t2 is measured according to the formula
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 　　2.
Different advantages Ubbelohde viscometer: simple equipment, convenient operation, and good experimental accuracy, is one of the commonly used methods
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The molar mass obtained by this method is called the viscosity average molar mass
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 　　Ostrich viscometer: easy to make, easy to operate, with high measurement accuracy, especially suitable for the study of liquids with small viscosity coefficients, such as water, gasoline, alcohol, plasma or serum
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 　　3.
Different precision Ubbelohde viscometer has one more tube than austenite viscometer
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Since the Ubbelohde viscometer has a tube 1, the liquid in the tube 3 is disconnected from the liquid in the tube 2 at the outlet of the lower end of the capillary during the measurement, forming an air-bearing suspension column
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 　　In this way, the pressure difference ρgh when the liquid flows down has nothing to do with the height of the liquid level in the tube 2, that is, has nothing to do with the volume of the liquid to be tested added, so the liquid can be diluted in the viscometer
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When the Ostenometric viscometer is used for measurement, the volume of the standard liquid and the liquid to be measured is the same because the pressure difference ρgh experienced when the liquid flows down is related to the height of the liquid level in the tube 2
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Therefore, the Ubbelohde viscometer has higher accuracy
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 　　The above is the relevant introduction about the difference between Ubbelohde viscometer and Ostwald viscometer.
I believe that everyone has a corresponding understanding of this after reading it.
When choosing, you should choose according to the actual situation.
I hope it will be helpful to everyone
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